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Chapter Three. The isolection plant breeding system

The result of 34 years of oat breeding and testing of dual-purpose varieties (for grazing and grain recovery) by the NSW Department of Agriculture are summarised in this chapter. A High-vigour cross (HvII 57-75) is identified which led to the release of Blackbutt (an F4 directed bulk type) in 1975, and Carbeen (an F6 plant progeny of the normal pedigree system) in 1981. This High-vigour cross also produced a number of high yielding F4 directed bulk types and F2 plant progenies bulked in the F3 as a result of their relatively high phenotypic uniformity. The highest yielding F3 bulk was numbered P4315, which although classed as an early oat, out-yielded all other varieties, including Blackbutt, for total biomass, following early sowings, and over a wide range of soils and climates and numerous seasons. The success of these oats was due to the Isolection plant breeding system pioneered by the Author at Glen Innes from 1957 to 1964. Other F4 directed bulks were P4314 (high-yielding both as a winter oat and a spring oat at Glen Innes) and P4318, both of which had large grains and, together with Blackbutt and P4315, were significantly superior over 5 grazing cuts (including the mid-winter cut) to Coolabah and all other advanced lines submitted by plant breeders from Temora, NSW, that were using conventional breeding methods during the same period. Selection of lines at the F2 generation has been demonstrated as a simple way of forecasting wider adaptability of early generation genetic material.

Introduction

The NSW Department of Agriculture (now the Department of Primary Industries) has been a world leader in the breeding of dual-purpose oat cultivars since 1921. This Department also has a strong tradition of releasing uniform oat varieties (meaning selection is in the sixth, F6, generation or later). These may take up to 15 years from making of the cross to release to farmers. With the present restriction of funds to Australian agricultural research, benefit/cost ratios in oat breeding research could be greatly improved by adopting a rapid “directed bulk” oat breeding method. This chapter describes the Isolection method which led to the breaking of world record yields.

The following quote by Falconer (1975) sets the context for this chapter:

“When large differences of environment, such as between different habitats, are under consideration, the presence of genotype-environment interaction becomes important in connection with the specialisation of breeds or varieties to local conditions…the important partition is into additive genetic variance versus all the rest…This partitioning is most conveniently expressed as the ratio of additive genetic to total phenotypic variance, Va/Vp, a ratio called heritability”.

Falconer (1975) notes that natural selection takes no account of heritabilities or genetic correlations and is therefore less efficient in improving fitness than artificial selection. The standard Mendelian genetic ratios, found with the differences between blue-eyed and brown-eyed individuals, are not usually exhibited in quantitative genetics, which depends on gene differences at many loci, the effects of which are not individually distinguishable. Nevertheless, the inheritance of quantitative differences depends on genes subject to the same laws of transmission and with the same general properties as the genes whose transmission and properties are displayed by qualitative differences. Quantitative genetics, therefore is simply an extension of Mendelian genetics.

The method for selecting high-vigour oat crosses

Overview

The scientific principles of Isolection plant breeding are essential for the breeding and testing of the oat crop. The process of breeding, however, must be separated from that of testing. This is dictated by the facts of Mendelian genetics and the danger of losing valuable material if testing is too severe and too early in the process of breeding. When the Author arrived at Glen Innes from Ireland in 1956, early breeding material was still being unevenly sown through the farm drill. This resulted in uneven stands, with individual plants unable to express and visually expose their yield potential or heritability, either for grazing or for grain production.

In 1957, the Author spent a week with Dr. Fred Mengersen at Temora, learning to achieve a high percentage of success in crossing oats, before returning to Glen Innes, on the New England Tablelands, where spring came a little later and in time to make the necessary oat crosses. This was an excellent climatic centre for stem rust (Puccinia graminis avenae) and smut (Ustilago sp.) inoculated nurseries. Glen Innes was also close to the crown rust (Puccinia coronata) nursery at Grafton research station, where rust developed earlier in the season and supplied inoculum for the Glen Innes disease nursery. This was followed by a spaced plant rust test to study infection and segregation.

The May sown F3 hand spaced rows were judged for uniformity and segregation of growth habit (from prostrate to erect) and for grain type and quality. Hand sown rows were opened up with the Planet Junior (a seeder manufactured by Powell Manufacturing) and were 2 foot (or 610 mm) apart. Plant density for the Isolection system is 3.66-5.38 plants/m2, as compared with 13.99-21.53 plants/m2 for the conventional system which it replaced during the development of the Isolection breeding method. More importantly, however, individual plants were far enough apart to express their potential yields relative to one another. The duplicate F3 sowing in August was for smut testing. The F4 test sown in early March was the first yield comparison, sown with the farm drill, and was subjected to the same rigours of winter grazing and frost as the normal biometrically designed and analysed small plot trials.

Table 3.1 shows that the seeds of the hybrid plants were grown in the potato breeder’s glasshouse to ensure no loss of germplasm to grazing or frost.

Table 3.1 Rapid method of breeding oats for large biomass yields.

Generation

Date sowing

Date harvest

Growing season

Testing sequence

F1
F2
F3 earlier (normal)
F3 later duplicate
F4

31.3.1958
19.11.1958
7.5.1959
11.8.1959
1.3.1960

9.10.1958
7.4.1959
31.12.1959
7.1.1960
17.12.1960

6 months
4.5 months
8 months
5 months
9.5 months

Glasshousea increase
Spaced plant rust test
Spaced plant grain test
Smut and maturity test grazing and grain trialb

a Field cross 26 x 21 made on 15.10.1957; b2 years from cross.

Table 3.2 Morphology and pathology of parents of the High-vigour crossa.

Cross A

Female

Male

Pedigree

Homozygosity
Early growth
Mature height
Harvest index
Grazing-frost
Foliage
Seed wt. (g/1000 seeds)
Groat %
Hectolitre weight (kg/hectolitre)
Milling suitability
Grain articulation
(specific trait)
Ustilago (smut)
Crown rustc
Stem rust

F.Ga (1183 G57)
G0-56-0-10 (F5)
Fixity proven
Prostrate
Tall (122 cm)
Medium
Very hardy (1/6)
Medium broad
32.30
70.50
51.13

Too small
50% A. sativa
50% A. byzantina
Resistant
MR (2/6)
R (0/6)

VRAF.VRSF (1309 G57)
G0-102-H0-G0-0-0-2 (F8)
Fixity proven
Prostrate
Short (90 cm)
High - 47.2%b
Very hardy (1/6)
Narrow leaves
44.00
74.00
54.24

Excellent
100% A. byzantina
-
Susceptible
MR (3/6)
S (6/6)

a Data obtained from row averages at Glen Innes 1959; b Harvest index determined subsequently at Tamworth 1961; c Crown rust is less important inland because grazing and cool winters discourage rank foliage growth.

More importantly, however, yields were greatly improved where homozygosity was observed in the F2 and F3 rows, as in the case of P4315. In the case of Blackbutt, the F2 bulk (886 G59) was found to be segregating for habit of growth in the F4, where only the truly prostrate plants were harvested to constitute the F4 bulk type, P4319.

An excellent team was available to determine grain quality on wet days and were happy to do hand spaced sowings (some of them had market gardens) and to cut the oat pasture to 1 inch (2.5 cm) above ground level using hand shears to avoid the inevitable loss of herbage involved with machine shears. This is consistent with more recent research on the Southern Tablelands of NSW (Dann et al. 1983), which found that grazing by sheep or cattle down to 2 cm did not reduce grain recovery yield any more than grazing down to 6 cm.

The early generation plan in Table 3.1 enables F3 bulks and F4 directed bulks to enter drill-testing respectively at 2 years and 4 years after the cross is made. For example, P4315 (F3 bulk) entered trials in 1960 whereas Blackbutt (F4 directed bulk) entered trials in 1962. Only certain crosses (phenotypically not too dissimilar) described concurrently should be attempted. The morphology and pathology of the High-vigour parents are described in this chapter (Table 3.2), with the view to making the most effective cross or crosses. For example, a cross between a winter oat variety and a spring oat variety, like Fulghum x Garry, is only a preliminary cross to transfer disease resistance from Garry to Fulghum. In Cross A (Table 3.2), a line from this cross was selected which combined Fulghum’s hardiness with Garry’s disease resistance. This close crossing concentrates the multiple genes needed for each type (Guerin 2003).

Features of the Isolection breeding method

The features of Isolection breeding are: (A) High rate of success in crossing oats, achieved in 1957, before starting, in order to produce a large number of homozygous F2 plants; (B) The two parents to be phenotypically similar (as in a narrow cross) but genotypically different; (C) The F2 generation plants to be widely spaced by hand, 4.52 plants/m2, at Glen Innes, as against 17.76 plants/m2 plants for the conventional drill sowing at Temora Research Station (representing the southern wheat belt). Hence the name of Isolection system, to “isolate” pure breeding lines, like P4315, and “select” them for yield testing in F3. The F2 plant of P4315 produced 600 seeds; (D) Linkage assists the rapid breeding method, by telling us that a winter cereal has morphological features like prostrate habit of growth and deep root system, correlated with resistance to frost, drought and grazing damage.

In about 1960, the Author replaced the previous conventional trial system of only 2 grazings per trial with one of 4 to 5 grazings, the latter being followed by a grain recovery trial. This enabled identification of a deeper root system, resistance to more severe frost and drought, and medium size grain with high bushel weight and low husk percentage, compared to Algerian’s large husky grains (from the Mediterranean centre of origin). This benefit of quality proved that high total yields could be combined with high grain quality.

Selection under low-stress conditions

The 1966 trial at Richmond was a comparison of the conventional and isolection methods of breeding. The new Isolection breeding method developed at Glen Innes Research Station, requires all early generation plants to be hand spaced, in order to provide the non-stress conditions to facilitate selection for heritability (Figure 3.2 and 3.3). This is to increase the chances of obtaining progeny with the desired characteristics required by the oat breeder. The conventional breeding system requires the early generation plants to be sown with a farm or other type of drill. Even at low rates of seeding, it is impossible to ensure even spacing of oat seeds. This is certainly more difficult than in the case of wheat seeds. It was clear that population stress conditions (obvious in a dry period following the germination of masses of seeds released out of the farm drill at the end of sowing each variety of seed) were detrimental to all varieties in the trial. As a result of this technicality and lack of labour, conventional breeding usually means selecting plants only in a later generation, as in the F6, where the type selected is presumed to be fixed. However, it should be noted that Algerian and Fulghum are still segregating in the F6 (see Chapter Two)

It is important to emphasise that non-stress selection will not reduce yields on the farm or in any trials where the optimum rate of seeding for maximum yields per unit area must be used, as the trials in this chapter demonstrate. As a reference point, in the Netherlands or Southern England, the density of field crops would be about 35 plants/m2. This concept of isolated selection, was later developed theoretically using a formula for heritability, h2, to obtain the additive breeding value, VA, giving:

h2 = VA/VP (phenotypic value) (Falconer and Mackay, 1996)

The total variance is the phenotypic (non-additive genetic and environmental) variance, VP, that needs to be reduced, in order to increase heritability percentage. Because of the true breeding nature of homozygotes, it is possible in the F2, to rapidly obtain a pure race with respect to any combination of parental factors provided that a large enough F2 generation was grown and tested. This concept is illustrated in the work conducted by the Author while breeding oats for NSW Agriculture at Glen Innes after 1956. His predecessor, James Carroll, had retired several years earlier from plant breeding and had already selected suitable lines from a moderately wide cross that he had made to incorporate crown and stem rust resistance from the Canadian oat Garry. A moderately wide cross, in this context, means a cross between different ecospecies like a winter oat, Avena byzantina var. Fulghum and a spring oat, A. sativa var. Garry, not a very wide cross like wheat x rye, which are different species. Nevertheless, a yield reduction is always involved but was easily overcome by only one cross in 1957, later referred to as the High-vigour cross (HvII 57-75): [F.Ga (1183 G57)], the female parent, x [VRAF x VRSF (1309 G57)], the male parent, where F = Fulghum, Ga = Garry, V = Victoria, R = Richland, A = Algerian and S = Sunrise were in the ancestry of the two 1957 rows at Glen Innes Research Station, NSW, Australia.

A number of other wider crosses were made to study linkage, but only this one close cross, the HvII, was necessary to accumulate the many genes for yield, frost resistance, drought resistance, tolerance to BYDV, resistance to smut, crown rust and stem rust. Figure 3.4 shows VRAF, one of the lines contributing to the genetic makeup of the male parent of this High-vigour cross.

The Isolection system has since been proven to assist in the detection of heritability, by several other workers, including Professor Kenneth Frey, although the mechanism responsible was said to be unknown at the time (Frey 1964). The non-stress environment (that is, separate sowing by hand) makes it possible to select the highest possible yielding lines, while the close spacing of a drill sowing does not. Professor Frey found similar results with oats at Iowa. He found that non-stress conditions resulted in the retention of oat strains with a wide adaptation reaction, whereas the stress conditions did not (Frey 1964). He referred to a formula of Falconer on heritability that confirmed his oat results (Falconer 1952).

In Japan, USA and the Netherlands, trials support the value of the non-stress conditions for the Isolection breeding system. Japanese wheat breeders also found that selection for heritability of yield was higher under high fertility than under low fertility conditions (Gotoh and Osanai 1959).

Breeders of spring rye, Secale cereale L., in the Netherlands, concluded that single plant selection for yield at wide spacing gives a higher progress and allows a better identification of outstanding genotypes, due to freedom from interplant competition (Pasini and Bos 1990).

Explaining “bulk” varieties

A clear distinction must be made between blends or multilines versus varieties compounded in F3, F4 or F5. Acceptable uniformity was achieved with an F5 line of soybeans (Auckland 1967) and with Blackbutt oats compounded or bulked in the F4 (Guerin 2003). A blend is artificially compounded of unrelated homozygous subpopulations and unlikely to maintain equilibrium. By contrast the early generation compounded variety has aggregate homeostasis, or greater stability in yield. This results from making and comparing crosses within a particular crop ecospecies. Crossing between different ecospecies, like winter growing types x spring types, ignores the need for multigenic breeding and often results in the need for backcrossing and in lower yields. Early, not later, generation selection is suggested by the Mendelian diagram for a trihybrid or three factors (Guerin 2003). In summary, high yield requires many genes.

Testing for dual-purpose capability in oat varieties

The importance of dual-purpose oats, especially in Eastern Australia, is so great that special emphasis has been given to grazing production research in NSW since 1921. The nutritional value of grazing exceeds that of the grain, which in itself has a higher biological value than the other cereals, both winter and summer crops (see Chapter One). The value of grazing relative to grain also increases by heavy, as opposed to lenient grazing and as one travels from south to north into the drier, sunnier regions with lower winter rainfall, richer soils and greater incidence of frost damage.

The standard grazing measurement techniques are as follows: (A) Continuous grazing, (B) Heavy grazing, (C) Lenient grazing, (D) No grazing, grain only, (E) Grain recovery after pasturing, (F) Total biomass, and (G) Pasture cut technique.

(A) Continuous grazing. Variations of this such as “lax”, “put-and-take” and rotational have been described by Wheeler (1962). They are expensive methods involving animal weighing, wool or lamb weights and few have been planned to incorporate new dual-purpose oats, bred in Australia in the past 25 years. Spurway (1975) is an exception in this respect because a suitable Northern NSW Tableland oat cultivar, Acacia, and an early February 25) sowing were studied, giving valuable knowledge to the Northern NSW Tableland sheep and wool-grower. The variety Cooba is not a true dual-purpose one as was still assumed (Fitzsimmons, 1978), when Archer and Swain (1977) tested the early maturing Cooba with a late March sowing, two fixed and unsuitable parameters making valid results questionable, at least for best Northern NSW Tablelands practice. Farming experience, together with trial results, both prove the necessity for early sowing as against late sowing for achieving greater total yields. This is demonstrated by comparing yields from different NSW Tableland sowing dates (Tables 3.3 and 3.4).

Table 3.3 The effect of grazing intensity on a range of cereal genotypes sown late March in a cool, moist, summer rainfall climate: F6 generation trial of High-vigour lines (1962)a.

Cultivar (no.)

Heavy grazing (t/ha)

Lenient grazing (t/ha)

Frost (0-6)

T4Pb

pGc

TYd

T2Pe

pG

TY

4P

2P

K69B.G.R, F4 (54)
Blackbutt (11)
886 G59 (46)
Blythe (12)
856 G59 (39)
Wintok
P4315 (38)
871-1 G59 (43)
Acacia (1)
856-1 G59 (40)
Winglen (W)
Bundy (15)
Klein 69B (53)
Fulghum (27)
Algerian (70)
Cooba (22)
Mugga (59)
Dun/Grey Winter
Abyssinian (B)
NIAB (WR)
Means
SD
CV (%)

2.60
2.24
2.15
2.47
2.07
2.43
2.26
1.96
2.07
1.87
1.77
1.98
2.11
2.32
1.55
2.13
1.62
1.70
1.53
0.89
1.99
-
33.2

0.60
0.90
0.95
0.47
0.82
0.36
0.47
0.69
0.57
0.69
0.78
0.57
0.43
0.21
0.90
0.31
0.44
0.47
0.50
0.50
0.58
0.30
35.0

3.20
3.14
3.10
2.94
2.89
2.79
2.73
2.65
2.64
2.56
2.55
2.55
2.54
2.53
2.45
2.44
2.06
2.17
2.03
1.39
2.57
-
-

2.29
1.95
1.76
2.08
1.87
2.08
2.25
1.93
1.80
1.82
1.59
1.84
1.99
2.56
1.63
2.34
1.48
1.42
1.28
0.83
1.84
-
23.9

0.67
1.05
1.00
0.98
0.72
0.79
0.86
0.95
0.68
0.82
1.06
0.73
1.11
0.64
0.91
0.70
0.69
0.61
0.81
0.62
0.82
0.30
35.0

2.96
3.00
2.76
3.06
2.59
2.87
3.11
2.88
2.48
2.64
2.65
2.57
3.10
3.20
2.54
3.04
2.17
2.03
2.09
1.45
2.66
-
-

1
0
0
0
0
0
1
1
0
0
0
1
1
2
2
2
0
0
0
0
0.6
-
-

2
0
0
0
1
0
3
3
1
1
0
3
2
4
4
4
0
0
2
0
1.5
-
-

a Trials were conducted at The New England Research Station, Glen Innes, NSW (cool moist climate). Date of sowing was 29.3.62. Season: Slow early growth; wet harvest weather. Date of harvest 30.1.63. This is not a comparison between heavy and lenient grazing due to the time difference in final grazing; b = total of 4 pasture cuts taken 15.6.62 (estimated); 7.8.62; 5.9.62; 2.10.62; c = grain recovered after pasturing; d = total yield of grazing and grain recovery = total biomass/energy; e = total of 2 pasture cuts taken on 15.6.62 (estimated) and 5.9.62.

Table 3.4 The effect of grazing intensity on a range of cereal genotypes sown in early March in a cool, moist summer rainfall climate: F7 generation trial of High-vigour bulk oats (1963) at Glen Innesa.

Cultivar
(Inventory Number)

Heavy grazing (t/ha)

Lenient grazing (t/ha)

T4Pb

pGc

TYd

T2Pe

pG

TY

Blackbutt (11)
871-G59 (43)
Klein 69B (53)
Cooba (22)
Blythe 12)
Fulghum (27)
856-1 G59 (40)
K69B.G.R., F4 (54)
856 G59, (39)
Winglen (W)
P4315 (38)
Wintok
886 G59 (46)
Algerian (70)
Bundy (15)
Mugga (59)
Acacia (1)
Abyssinian (B)
Dun (Grey Winter type)
NIAB (WR)
Means (excluding B & WR)
SD
CV (%)

3.85
3.88
3.20
3.23
2.79
2.89
2.53
2.38
2.35
2.31
2.18
2.10
1.80
1.83
2.09
1.84
1.66
1.95
1.05
0.15
2.44
-
30.5

0.47
0.42
0.70
0.29
0.47
0.18
0.35
0.49
0.50
0.26
0.28
0.35
0.59
0.42
0.13
0.36
0.35
NILf
0.45
0.03
0.39
0.19
36.1

4.32
4.30
3.90
3.52
3.26
3.07
2.88
2.87
2.85
2.57
2.46
2.45
2.39
2.26
2.22
2.20
2.01
1.95
1.50
0.18
2.84

-

2.80
2.38
3.29
2.95
2.15
2.06
2.49
2.95
2.21
2.39
3.40
1.86
2.58
1.74
1.98
2.08
1.75
1.59
1.79
0.14
2.38
1.08
33.2

0.48
0.25
0.75
0.17
0.43
0.16
0.48
0.44
0.31
0.30
0.19
0.38
0.50
0.34
0.22
0.39
0.39
0.03
0.43
0.09
0.37
0.21
43.2

3.28
2.63
4.04
3.12
2.58
2.22
2.97
3.39
2.52
2.69
3.59
2.24
3.08
2.08
2.20
2.47
2.14
1.62
2.22
0.23
2.75

-

a Date of sowing was 6.3.63 at the New England Agricultural Research Station, Glen Innes, NSW. Severe grazing was measured by 4 pasture cuts before each close even grazing by a large flock of sheep. Lenient grazing was similarly measured by 2 pasture cuts; b = total of 4 pasture cuts; c = recovery for grain harvest; d = total yield of grazing and grain recovery; e = total of 2 pasture cuts. W = wheat; B = barley; WR = winter rye; f = barley failed to recover after severe grazing. Grazing dates: 1.5.63; 24.5.63; 5.9.63; 3.10.63 (heavy series); 24.6.63; 18.9.63 (lenient series). Season: June very wet; dry after September grazings. Date of harvest 30.1.64.

(B) Heavy grazing. This involves 4 or more grazings. This is synonymous with intensive grazing and is in between continuous (in all its variations) and lenient grazing. This reveals more accurately than (C) cold weather and other growth rates. A better term to describe this might be “close” or frequent grazing.

(C) Lenient grazing. This involves only one or two grazings and is intermediate between heavy grazing and no grazing. The trials presented in this chapter show that heavy grazing gives a higher total yield than lenient grazing including Tables 3.5-3.8. Lenient grazing is incapable of revealing the true dual-purpose cultivars with high protein yields of herbage undamaged by severe frosts, and also likely to be of a higher digestibility (Pearce et al. 1987; Guerin 1966). Lenient grazing causes more frost and shade damage than heavy grazing as in Cooba and Fulghum (Table 3.3) and decreases digestibility (Fagan and Milton, 1931). A better term to describe this might be “lax” or infrequent grazing.

(D) Grain only trial. They are a reference point for grain (or hay) yield potential, lodging resistance and susceptibility to diseases like crown and stem rusts, because ungrazed oats can grow tall and rank.

(E) Grain recovery after pasturing. This is especially important in the case of lenient grazing but also in the case of heavy grazing, where the third and fourth cuts of a frosted variety are still yielding well, although much of the material has been “burnt” by frost and is probably low in digestibility but not showing a significant inferiority in grazing yields. This has been the case at Glen Innes, as recorded by Guerin (1966). In this particular case it is the grain after grazing (pG) yield that demonstrates the significant yield superiority of the true dual-purpose oat in conjunction with total yield (Tables 3.3 and 3.4).

(F) Total yield or total biomass. This is the final arbiter of the value of the dual-purpose oat for energy purposes. On a weight-for-weight basis, however, the dry matter pasture yield (if not damaged by frost) has twice the protein content of the grain. This is important for growing, fattening, lactating and pregnant animals. On the other hand it is a waste of high quality feed to put dry adult stock on to oats.

(G) Pasture cut technique. Only the “crash grazing” (Dann et al. 1977), or severe grazing technique is used, both for heavy and lenient grazing comparisons. This technique prevents selective and uneven grazing by sheep, who are “shy” grazers and must belong to a flock large enough to eat the experimental area down to a constant level of about 2 cm (within a few days) above ground level (Hodgson et al. 1981) (Figure 3.1). To avoid soil contamination of the cut herbage, the NSW Department of Agriculture at Glen Innes used hand sheep shears. This gives the operator more control of cutting height, and less noise to contend with, than in the case of power-driven equipment. Moreover, the work is done more accurately by this method. As most of the good varieties are prostrate growing, power-driven equipment would be less accurate. Even with 4 replications of each treatment, variation of grazed oats under the stress of the cold climate of the Tablelands in NSW, and sometimes waterlogging, is often high. The first grazing and cut are taken about 6-8 weeks after sowing. A fresh sample of the plot length is taken before each grazing, as sheep tend to over-graze these protein rich areas. This is due to a vigorous emergence of new shoots in the case of high tillering cultivars like Blackbutt. These new shoots are rapidly devoured by the sheep during the day or two they occupy the experimental area. It is for this reason that good grazing cultivars like Blackbutt actually produce much more grazing in practice than grazing trials (even those grazed four times) actually record. Because of the prostrate, low-growing habit of these cultivars, a motor mower cannot replace the hand cutting method.

The converse is also true. Fertility is transferred by the sheep from the good grazing plots to the poor grazing plots which therefore record a higher yield than they would in farm practice. Sheep are therefore considered essential for testing the full potential of the oat crop.

Testing of high-vigour lines and varieties

Yield increases from High-vigour lines and varieties

Extensive yield testing of the High-vigour oat lines and varieties have been carried out since late 1950s.

Table 3.6 shows the overall superiority of oats bred at Glen Innes compared with conventionally bred lines for frost resistance, cold weather growth to supplement pastures and long season intensive grazing with hay recovery on the richer type of soil in summer rainfall regions. This trial, conducted in Richmond NSW in 1966, also demonstrated the superiority of the Isolection breeding technique over conventional breeding and this is further discussed in Chapter Six

Table 3.8 shows the value of grazing, by return of nutrients through the grazing animal (Wilson 1968) in boosting grain yields, an option not usually open to specialised grain oats, wheat or barley varieties. Here, P4315, Sual, Cassia and Blackbutt broke the world oat yield record (Fageria 1992), with P4315 proving significantly the highest yielder for the 2 pasture cuts.

The oat varieties Cassia, Coolabah, Hakea (Roberts 1989a) and Yarran (Roberts 1989b), although suitable for lenient grazing, are not true grazing-hardy, dual-purpose oats as is the High-vigour line, P4315. Carbeen is only slightly handicapped by its straw being taller than Blackbutt, while Hakea is taller and weaker than Carbeen. Yarran is susceptible to BYDV. Tolerance to this disease is essential under high and summer rainfall conditions.

Lenient oat grazing dry matter yields in South Australia (Craig and Potter 1983) were only 14% of those of continuously grazed pasture. By contrast, Algerian oats seeded at 90 kg/ha yielded 4 times that of ryegrass-clover pasture (Crofts 1966). The same variety seeded at 180 kg/ha with 67 kg/ha of nitrogen carried 30 ewes per ha or 8 times the carrying capacity of the pasture at Orange (Crofts 1966). At Armidale, which is similar in climate to that of Canberra and typical of much of eastern Australia, the ratio of oat to pasture growth in areas of dormant winter pastures (which contain no sub-clover) was 10:1 (Wheeler 1963).

A comparison of the Isolection lines with conventionally bred oat lines from Temora Research Station (NSW) and other winter rainfall areas was made in 1966 at Hawkesbury Agricultural College, Richmond, NSW (Table 3.6). The highest yielding lines were all from the High-vigour cross and were identified as P4315, P4314, Blackbutt, 871-1 G59 and 871 G59, in that order, all significantly higher yielding than conventional lines, in 5 grazing yields and a hay recovery cut. All 5 lines produced grain of high test weight and low husk percentage, ideal for stock feeding. The top 5 yielders tested in this trial, by 5 grazings and a hay cut, were High-vigour lines. In this trial, P4315 produced over 10 tonnes of biomass per ha in a dry season (50% of the normal rainfall), with no irrigation. P4315 also produced the highest mid-winter growth of 1.45 tonnes in 33 days. This data is presented in Table 3.6 and the trial plots are shown in Appendix B. This daily production of 44 kg would support 35 sheep per ha, assuming that each sheep required 1.24 kg daily (Crofts 1966). Blackbutt was the highest yielder for total grazing, demonstrating its high recuperative ability. Blackbutt is a very high tillering variety with winter prostrate habit. P4314 was the highest yielder of hay. Blackbutt was only the sixth highest yielder of hay, indicating its short straw and lodging resistance.

Cooba and Coolabah were found to be unsuitable for dry winters and were low yielders under heavy grazings. As these are the two most popular varieties in the state, their replacement by Carbeen and Blackbutt would, for most of the state, considerably increase livestock productivity and farm profitability.

At Tamworth Agricultural Research Institute, in 1973, the early variety P4315 yielded significantly more than most varieties for 2 grazing cuts and recovered 19.8 tonnes of grain per ha (Table 3.8). In the late-maturing class, Blackbutt has yielded significantly more than all other oats, winter wheats and triticales, for grazing and grain recovery, from 1966 to 1999, on the Tablelands, Cootamundra and eastern Australia generally. It is still recommended in 2005 (McRae et al. 2005).

The high grain after grazing yield of P4315 in the Tamworth trial (Table 3.8), broke the world grain oat yield record of 10.6 t/ha by 90% (Fageria 1992) and the world wheat yield record of 15.7 t/ha by 26% (Evans 1996). This can be explained not only by the excellence of the season of 1973 at Tamworth but also by consistent and sound soil management practises like contour cultivations and fallowing for weed control, ample soil water storage and early plantings over many years and, above all, the dedication of the Agronomist, Mr. Gerry Hennessy, who conducted the trial. Lenient grazing in this trial may have facilitated the high grain recovery yields. These ideal growing conditions enabled the full expression of the genetic potential of the varieties and lines tested in this trial.

Varieties bred at Temora and research stations in the winter rainfall area of southern Australia are unlikely to be productive in the cold winters and summer rainfall of the northern New England Tablelands of NSW as set out in 2 statistically designed trials, typical of many tests, in 1969 (Table 3.9). The outstanding selection in these 2 trials and other cold winter areas, P4315, had an exceptionally high rate of growth in the coldest month of the year, July. It alone was significantly superior in this respect to Acacia and Klein 69B from Argentina, hitherto the best mid-winter varieties when livestock have their greatest food requirement. Seed of P4315 was not maintained in the germplasm collection transferred to Temora, contrary to the Author’s request for release of this High-vigour line to farmers in 1966. The Author recommended that P4315 should replace Cooba because of greater frost resistance and equally early maturity for the convenience of wheat growers, rust resistance, higher hectolitre weights and much greater straw strength. P4315 had proven to be the highest yielding oat line variety of all lines and varieties tested in NSW by the Author or in trials that the Author is aware of.

Figure 3.2-3.5 and 3.10 illustrate some of the varieties and lines used and developed during the breeding of the High-vigour cross, their spacing in the field, their parents, and field testing.

Figure 3.1 Results of heavy grazing by sheep (Top); The pasture cut technique using manual shears at Glen Innes, NSW (Bottom).

 

Figure 3.2 (Left) Tall strong straw of Fulghum (F) x Garry (Ga) (F.Ga or W4595), typical of the F.Ga cross; (Right) Close up of the panicles of F.Ga, the female parent of the High-vigour cross.

Table 3.5 Second testing of High-vigour bulk oats in north-west NSW, contrasting cooler elevated site (Tamworth) with warmer plains site (Narrabri): F5 generation trial (1961).

Cultivar
(Inventory Number)

Tamworth (mild but frosty)

Narrabri

CWGa
(t/ha)

Frostb
(0-6)

T4Pc
(t/ha)

pGd
(t/ha)

TYe
(t/ha

pHf
(t/ha)

G/Hg
%

Gh
t/ha

P4315 (38)
F.Ga (30)
Klein 69B (53)
871 G59 (42)
A x Lag (4)
856 G59 (39)
Fulghum (27)
K69 B.G.R. (54)
Acacia (1)
886G59 (46)
Algerian (70)
Cooba (22)
Mugga (59)
1309 (23)
Bundy (15)
843 G59 (37)
Burke (17)
Belar (9)
Orient (210)

SDj
Date of sowing:

1.71
1.44
1.40
1.61
1.24
1.40
1.05
1.19
1.33
1.11
0.93
1.34
1.02
1.14
0.83
0.75
0.58
0.52
0.22

0.31
14.3.61

0
1
0
1
0
0
1
1-
0
1
4
3
0
1
2+
4
4
3
6

-

6.97
6.06
6.45
6.56
5.37
6.15
6.03
5.29
5.66
5.35
4.91
5.99
4.86
5.20
4.58
4.76
4.11
3.82
4.18

1.61

1.63
2.48
1.78
1.60
2.31
1.46
1.49
2.15
1.59
1.79
2.09
0.86
1.91
1.05
1.59
1.29
1.24
1.14
0.43

0.55

8.60
8.54
8.23
8.16
7.68
7.61
7.52
7.44
7.25
7.14
7.00
6.85
6.77
6.25
6.17
6.05
5.35
4.96
4.61

-

3.61
-
4.15
3.51
-
2.88
3.12
-
-
-
-
2.07
-
2.18
-
-
-
-
-

0.46

45.2
-
42.8
45.1
-
48.6
48.0
-
-
-
-
44.8
-
47.2
-
-
-
-
-

-
3.5.61

1.09
0.52i
2.69
1.19
0.24i
0.71
-
-
0.50i
0.28i
1.05
0.82
0.05i
0.69
1.38
0.74
1.71
2.09
4.38

0.41

a Cold weather growth (CWG) measured by 3rd cut; high fertility soil; b Frost damage score of 3 and over lowers grain recovery yields; c Total of 4 pasture cuts, each immediately followed by sheep grazing trial area down close to ground level on 16.5.61, 10.7.61, 23.8.61 and 19. 9. 61; d Grain yields after grazing; e Total yield of c + d; f Hay recovered after grazing at grain ripeness stage; g Relative harvest index, grain as a percentage of hay; h Grain only trial, high fertility soil; i Specialised winter oats, too late maturing for the north-west plains. All yields in tonnes/ha, with pasture as dry matter; j All trials are biometrically designed and analysed to give significant differences in yields between all the lines tested.

Table 3.6 A comparison of southern and northern NSW bred cultivars under intensive grazing and hay recovery: F10 generation testing of High-vigour lines at Richmond (1966).

Cultivar (Inventory Number)

5P
(t/ha)

pH
(t/ha)

5P+pH
t/ha

Tillers killeda

F score (0-10)

July P
(t/ha)

P4315 (38)
856 G59 (39)
Blackbutt (11)
871-I G59 (43)
871 G59 (42)
Klein 698 (53)
Cooba (22)
Fulghum (27)
F x V (122)
Coolabah (105)
F x Avon (121)
Avon x Fk (116)
Avon x Os (117)
F x Avon (120)
Fulmark (107)
M1305 (118)
Yates Algerian (70)
SD

6.55
6.21
6.67
5.66
5.60
5.01
5.18
4.87
4.21
4.09
3.89
3.96
4.04
3.45
3.78
3.36
3.38
0.90

3.62
3.70
2.86
2.97
2.99
3.37
2.21
2.20
2.47
2.08
2.23
1.93
1.81
2.11
1.70
1.48
0.60
0.99

10.17
9.91
9.53
8.64
8.59
8.38
7.39
7.07
6.68
6.17
6.12
5.90
5.85
5.57
5.48
4.85
3.98
1.54

4
0
4
0
3.6
0
14
30
19
76
43
40
157
106
165
132
35
-

1
1-
1
2
2
2+
3+
3
4+
6+
4+
7+
8
7
9
7
8
-

1.45
1.23
1.35
0.83
0.74
0.72
0.95
0.64
0.52
0.45
0.36
0.28
0.33
0.23
0.20
0.25
0.19
0.34

a No. per row; 5P = 5 pasture cuts as DM (dry matter); pH = air dried hay after pasture; F = frost (0 = no damage, 10 = extreme); Date of sowing 25.3.66 at Hawkesbury Agricultural College, rich alluvial soil, no irrigation; dry season (rainfall 50% of 86 year mean); seeding rate 72 kg/ha; rate of fertilizer, in seed drill only, 22.4 Kg N + 22.4 P2O5/ha. Cultivar inventory reference numbers with 3 digits were bred in Temora, a Conventional breeding centre, and those with 2 digits, excepting Klein 69B, Cooba, Fulghum and Algerian, were bred in Glen Innes using the Isolection breeding system; SD = significant difference, obtained by biometrical analysis performed by NSW Agriculture Biometricians at Rydalmere, NSW, Australia, during 1966-1967.

Figure 3.3 Non-stress growing environment. A plastic covered frame (Top) for establishing rust infected plants, transplanted from the subtropical station at Grafton, and designed to spread rust and determine rust resistant plants; (Bottom) Inspection of individual oat plants.

<3.4b here>

Figure 3.4 Non-stress growing environment (Top) Fulghum x Garry (female parent of the High-vigour cross) showing its strong straw; (Bottom) Wide spacing of individual oat plants.

Figure 3.5 Crossing of a rust resistant line, of oat, 0600 (Top) and VRAF (W4890) (Bottom).

P4315, the highest yielder, was solely derived from an F2 plant that yielded 600 seeds, of which 540 seeds were spaced out in row 851 G59 in the F3 generation, as set out with other pedigrees in Chapter Two (Table 2.8). In the 1966 trial at Richmond NSW, it produced more tillers per plant (3.3) than Fulghum (2.6) and Cooba (2.5). The groat percentages of the grains were equal to those of Cooba, in a wide range of climates. Although the grains were smaller than those of Cooba, they were better for stock feed with their higher weight per bushel, due to its resistances to rust diseases and to lodging. Mr. Norm Markham, District Agronomist for West Wyalong, informed the Author on 21st April, 1972 that P4315 line was exceptional for grazing in the Grenfell area (Guerin 2003). Many other similar trials in eastern Australia have been conducted or recorded (Guerin 2003).

Results at Cowra showed that 3 High-vigour lines headed by Blackbutt, produced from 7 to 8 tonnes of total yield (Table 3.7) (Guerin and Guerin 1992). This was better achieved by 4 grazings than by 2 grazings (i.e. the lenient series). The frost susceptible varieties like Cooba and Coolabah performed better with lenient than with heavy grazing. This significant finding, from Cowra, Richmond, Glen Innes, Orange and other trials throughout NSW (NSW Agriculture, 1960-1977) has not been taken into account by later research work. For example, Lovett and Matheson (1974) studied only lenient grazing and did not realise that oat varieties bred for heavy grazing were superior to wheat, barley and rye for total biomass energy and, because of higher grazing yields, one could confidently state much higher protein yields (Tables 3.9 and 3.10). Similarly Craig and Potter (1983) did not study beyond 2 grazings and their sowing in late May was too late for maximum oat grazing winter production which should significantly outyield pasture growth (Table 3.11 and 3.12).

Algerian was badly frosted in the Nepean valley at the River Farm of Hawkesbury Agricultural College (Richmond, NSW) in 1966, as illustrated in Figure 3.7 (page 95) and reflected in the yield data (Table 3.7). The straw of Algerian, like that of Klein 69B, is tall and weak and unsuitable for grain only crops. In hectolitre or bushel weight (weight per unit volume) and groat percentage (weight of whole grains less the hulls), the grains of KIein 69B are like those of Algerian, which are inferior to those of the Glen Innes oats. In the 1966 trial referred to above, it was a dryland sowing which received only 50% of the 85 year mean annual rainfall and was a notably dry and frosty season. The five top yielding varieties in this trial were derived from the High-vigour cross, as shown in Figures 3.7-3.9. A total biomass yield of 5 grazings and a crop of hay amounted to over 10 tonnes per ha in the case of P4315, the highest yielding line in the trial. By contrast Algerian produced only 3.4 tonnes per ha, similar to Croft's yield from 5 grazing cuts at Orange in the Central West Tablelands of NSW (Crofts 1966). In addition, the Richmond 1966 trial received one-third of the nitrogen applied by Crofts at Orange. The fertilizer was applied only at sowing time and the lower seeding rate suited the season and the soil, a rich alluvial clay loam which encouraged the high tillering capacity of the High-vigour lines. The stocking capacity of P4315 was potentially equivalent to 42 adult sheep per ha for 255 days, on the basis of the results at Orange. Professor Lloyd-Davies, however, regards dry matter yields as more reliable than stocking rates5.

Figure 3.6 shows the poor grazing capacity of the specialised grain oat, Swan, from Western Australia, in comparison with P4315 and Cooba at Temora, a site with less frost damage than Richmond or Glen Innes (both located in NSW).

Figure 3.6 A typical Western Australian bred cultivar, Swan, showing poor dry matter recovery under a 5 grazing cut regime at Temora, New South Wales, 1969, in comparison with moderately frost-hardy Cooba and very frost-hardy P4315.

Table 3.7 Heavy (4 P cuts) and lenient (2 P cuts) grazing and grain recovery (pG) at Cowra: F10 generation testing of the High-vigour lines (1966)a.

Cultivar
(Inventory Number)

Heavy grazing (t/ha)

Lenient grazing (t/ha)

4P (DM)f

pG

Total Y

2P (DM)

pG

Total Y (R)

Blackbutt (47)
P4315 (38)
P4314 (39)
Coolabah (105)
Fulghum (27)
Cooba (22)
Avon x Os (117)
F x Avon (120)
871-1 G59 (43)
871 G59 (42)
Bundy (15)
F x Vic (122)
Blythe (12)
Avon x Fk (116)
Acacia (1)
Algerian (70)

2.49
2.95
2.72
2.47
2.83
2.56
2.11
1.78
2.49
2.25
2.30
2.32
2.50
1.90
2.26
2.11

5.26b
4.74b
4.81b
4.26b
3.65b
3.60b
3.30b
3.43c
2.70c
2.62c
2.41c
2.31c
1.68c
2.20c
1.80c
1.67c

7.75
7.69
7.53
6.73
6.48
6.16
5.41
5.21
5.19
4.87
4.71
4.63
4.18
4.10
4.06
3.78

0.86
1.11
0.80
1.36
1.33
0.99
1.17
1.18
0.97
0.92
1.18
1.02
-
1.26
-
1.08

6.21e
6.42e
6.12e
5.43e
4.38e
5.61e
3.83d
5.37e
3.37e
5.71e
6.06e
3.69e
-
5.20e
-
2.45d

7.07
7.53
6.92
6.79
5.71
6.60
5.00
6.55
4.34
6.63
7.24
4.71
-
6.46
-
3.53

SD
CV (%)

n.a.
-

n.a.
-

-
-

0.23
14.4

0.71
10.3

-
-

a Pasture cuts were weighed green and converted to DM (dry matter) by using factor of 20% dry matter as found at Tamworth Agricultural Research Institute, which has a mild winter climate like that of Cowra but is more subject to frost damage than is Cowra; Date of sowing 25.3.66 (heavy grazing) and 25.3.66 (lenient grazing); b Date of harvesting was 12.12.66;
c
Date of harvesting was 22.12.66; d date of harvesting after heavy grazing was 22.12.66;
e
date of harvesting after lenient grazing was 30.11.63; f Dates of grazing were 17.5.66, 22.6.66, 25.7.66 and 29.8.66 (heavy grazing); g n.a. = Heavy grazing results not analysed.

Table 3.8 Lenient grazing and grain trial: F17 generation testing of High-vigour bulk oats.

Cultivar
(Cultivar Number)

Pasture Yield
(2 cuts) (t/ha)a

Grain Recovery Yield
(t/ha)b

Total Yield
(t/ha)c

P4315 (38)
Sual (63)
Cassia (103)
Blackbutt (11)
Cooba (22)
Klein 69B (53)
Coolabah (105)
Bundy (15)
Algerian (70)
Mugga (58)
Avon (101)
Acacia (1)
SD
CV (%)

0.58
0.49
0.47
0.48
0.62
0.57
0.51
0.54
0.47
0.45
0.43
0.53
0.08
10

19.83
19.66
16.14
14.50
10.36
7.26
7.31
5.95
5.98
5.62
3.92
3.80
1.71
12.4

20.41
20.15
16.61
14.98
10.98
7.83
7.82
6.49
6.45
6.07
4.35
4.33
-
-

a Total of 2 pasture cuts to measure 2 grazings; b Grain recovery yields were a NSW Department of Agriculture and world record for oat yields; c Total yield of grazing (as dry matter) and grain in tonnes/ha. Excellent season; crown rust and stem rust severe but not affecting P4315 or Sual. Date of sowing 4.5.73 at Tamworth Agricultural Research Institute; d = coefficient of variation.

Table 3.9 Effect of multiple grazing cuts on grain and pasture yields on a range of oat cultivarsa.

Variety

Site 1 Yields (t/ha)

Site 2 Yields (t/ha)c

Cut 1b

Cut 2

Cut 3

Cut 4

Cut Total

Cut 1

Cut 2

Cut Total

Grainc

Acacia (1)

1.07

1.66

0.97

0.31

3.96

1.12

0.99

2.11

1.38

Algerian (70)

1.02

0.94

0.66

0.21

2.81

1.27

0.79

2.06

1.26

P4315 (38)

1.28

2.19

1.34

0.26

5.12

1.17

1.71

2.85

2.10

Blackbutt (47)

0.90

1.76

1.43

0.46

4.56

1.07

1.47

2.52

2.07

Cooba (22)

1.10

1.52

1.08

0.30

3.96

1.17

1.59

2.75

1.56

Coolabah (105)

1.07

0.87

0.79

0.16

2.86

1.42

1.02

2.45

1.08

Fulghum (27)

0.93

1.13

0.80

0.24

3.11

1.71

1.55

3.25

1.32

Klein 69B (53)

0.99

1.52

1.27

0.36

4.14

1.30

1.33

2.66

1.83

Mugga (58)

1.20

1.40

1.30

0.38

4.31

1.12

0.97

2.08

1.65

Saia (60)

-

-

-

-

-

1.55

0.97

2.52

1.40

Abyssiniand

-

-

-

-

-

1.18

1.68

2.86

2.05

Windebrie

0.53

0.63

0.84

0.16

2.16

-

-

-

-

Cutting datef

65

148

247

276

-

-

-

-

-

SD (t/ha)g

0.48

0.48

0.48

0.48

1.05

0.21

0.39

0.48

0.40

CV (%)h

-

-

-

-

39.3

9.9

21

11.5

17.3

a Trial conducted in New England, NSW in 1969; Site 1-sown 4 March 1969 with 4 replicates at Mr. Shireberg’s farm, Niangula, and Site 2 - sown 2 April 1969 with 3 replications at Mr. Lane’s farm, Reddestone, NSW; b Dry weight of pasture sampled at the designated cutting date; c Grain harvested after two pasture cuts; d Barley variety; e Winter wheat variety; f Days after sowing (not recorded for Site 2); g Standard deviation; h Coefficient of variation.

Table 3.10 Grain and pasture yields from 1955 competing crop trialsa.

Crop

Variety

Pasture Yield (t/ha)

Grain Yield (t/ha)e

Frost Damagef

Ear Emergence
(Days after sowing)g

Cut 1b

Cut 2c

Totald

Oats

Fulghum (27)

2.36

2.51

4.87

0.717

3

203

Oats

Acacia (1)

2.46

1.84

4.30

1.375

3

119

Oats

W4477

1.57

2.22

3.79

1.008

2

206

Oats

W4484

1.79

1.84

3.64

0.654

4

199

Barley

Cape

1.79

1.59

3.39

0.790

4

204

Barley

Pryor

1.62

1.59

3.21

0.840

4

204

Wheat

Celebration

1.12

0.89

2.01

0.914

5

214

Winter Wheat

Winglen

1.29

0.66

1.96

1.451

1+

216

Winter Wheat

German P4 Cel.

1.18

0.63

1.81

1.116

3

217

a The trial was conducted in 1955 at Glen Innes in New England, NSW and data originally reported by Mr. Lancaster (1956, unpublished); b Cut was taken on 5 May 1955 (44 days after sowing); c Cut 2 was taken on 30 August 1955 (161 days after sowing); d Significant difference=1.10t/ha and standard deviation=23.4%; e Significant difference = 0.252t/ha and standard deviation = 17.0%; f On a scale of 0-6, Winglen was the least frost damaged and Celebration was the most damaged variety; g Sowing date was 22 March 1955.

On the New England Tablelands, pastures which were ungrazed from mid February to June-July produced 515 kg per ha in 1958 and 280 kg per ha in 1959, an average of 397 kg per ha (Wheeler 1963), which is similar to that at Orange in 1966 (Crofts 1966). In the study by Wheeler (1963), the normal oat sowing without nitrogen, outyielded pasture by a factor of 3.9 in comparison with a factor of 5 to 10 in New England. These results indicate that these High-vigour oats have an even greater potential in the north of NSW where growers are obliged to use the frost resistant varieties.

Sual, a rust resistant line of Sydney University derived from Algerian, also broke these world yield records by a similar margin to that of P4315, but was significantly inferior to P4315 in the total yield of 2 pasture cuts. Grain recovery yields of Cassia and Blackbutt also broke the world oat yield record and Cooba, the check variety, was equal to the oat record.

Competing crop trials

The NSW Department of Agriculture began competing crop trials of oats, wheat, rye and barley at Glen Innes in 1921. By 1935 it was well established that oats was the most productive crop under grazing during the severe winters of the New England Tablelands together with recovery of hay and grain. By that time, mostly oat varieties were being tested for production of grazing material, hay and grain from plantings in February. The reason for the early sowings was in order to obtain four grazings. As a continuation of the 1921-1939 trials, oats were compared at regular intervals with the latest varieties of wheat, barley and rye and more recently with the newer crop triticale. The objective trials of wheat, oats and barley recorded in this chapter are quite typical of many such comparisons made over the last 40 years in NSW. Therefore production statistics are too subjective. To make more sense of production statistics, details like those of the Research Stations, District Agronomists and Cooperating Farmers should be collected and given top priority by the Bureau of Statistics (Forsberg and Reeves 1995). This section of this chapter is an attempt to do this.

Pasture research scientists in Australia have had great success with the long-season variety from the High-vigour cross, Blackbutt. Muldoon in 1986, found that Blackbutt had a higher dry matter percentage in primary growth than Cooba and Abysinnian barley. He also found that Blackbutt had the highest cumulative regrowth of any cereal, well ahead of the barleys, which declined considerably for the third regrowth. Muldoon was comparing oats, barley, wheat, cereal rye and triticale under irrigation at Trangie, NSW in 1978 and 1980 and has made a great contribution to pasture and grazing research (Muldoon 1986). On the Southern Tablelands of NSW, Dann et al. (1983) found that Blackbutt oats yielded considerably more than Isis wheat in herbage availability, grazing days, liveweight gain and grain yield. They also found that severe grazing (down to 2 cm) never reduced the number of spikes or panicles per unit area and that cattle were not significantly superior to sheep for liveweight gain on grazing oats but were greatly superior for financial return because of the 100% higher price/kg live-weight obtained, in that year, for the cattle (Dann et al. 1983).

Table 3.13 shows the continuing supremacy of Blackbutt oats for grazing and grain in the relatively dry, frosty winters of NSW, even over the most recently bred variety, Eurrabie, selected at Temora under the conventional system of breeding. Only the yields of the highest yielding winter wheat, Tennant, are included in Table 3.13. In addition to the superior grain recovery yields of Blackbutt, its superior grain feed quality, high-test weight and low husk percentage should also be considered by Southern Tableland farmers in choosing a winter cereal grazing crop.

Carbeen was included in grazing and grain recovery trials in South Australia (Craig and Potter, 1983). The trial was sown on 29 May, 1980 on a solodised solonetz soil with 100 kg/ha of superphosphate. The area was evenly grazed by sheep (an excellent source of fertiliser and even grazing). Comparing 0, 1 and 2 grazings, the erect varieties yielded more grain after one grazing than after 0 or 2 (Table 3.11 and 3.12). The most prostrate variety, Carbeen, was the only variety to yield more grain after 2 grazings than after 0 or 1 grazing in this trial. The second grazing was on 5 September 1980, after a pasture cut to 2.5cm above ground level. This section of the trial was grazed by 100 sheep for 3 days down to a uniform height of 2.5cm above ground level. The prostrate variety, Carbeen, from the High-vigour cross, significantly outyielded all other varieties in grain recovery. The effect of a single grazing event led to higher grain protein in A. strigosa compared to common oats species (Table 3.11).

Competing crop trials conducted in New England, NSW, demonstrate the superiority of the High-vigour lines. At Glen Innes, the winter of 1955 was cold and cloudy after the first grazing. Although Winglen winter wheat was the least visibly affected by frost damage (scoring 1+ out of 6), in Table 3.10, it was significantly inferior in total grazing to all the oat and barley varieties. The winter wheats were set back by the cold weather and produced very little feed for the late August grazing. The oat results showed that this cereal was the most effective for winter grazing and grain recovery, while both oats and winter wheats were the best grain yielding cereals. In this trial there was no significant difference between Acacia and Winglen winter wheat.

This flexibility or versatility of oats compared with other cereals was further highlighted at the New England Experiment Farm at Glen Innes in 2 trials in 1953 (a dry season) and in 1954 (a wet season) (Table 3.14). Oats yielded higher than winter wheat, spring wheat and barley in both seasons, with Acacia oats outyielding all varieties of wheat and barley in both seasons, and significantly so in the dry season. Barley and spring wheat responded the most to wet season-oats the least, with the exception of Acacia oats which significantly outyielded all varieties of wheat and barley in both seasons.

The relatively new crop Triticale (variety Empat) was inferior in pasture yield to the High- vigour lines (Table 3.15) as were the wheats. Barley is a “quick early” lenient grazing cereal which does not recover well and is susceptible to frost and waterlogging at Glen Innes (Tables 3.3, 3.4, 3.10 and 3.14).

Freebairn (1986) described a very large area of the Coonabarabran and Coolah Shires, 900,000 ha of agriculture, with acid soils, low in natural N and P. Before clearing, this country was covered with ironbark, bloodwood, pine, gum, apple box and a variety of undergrowth. Freebairn highlighted the value of lupins, triticales and rye. He found Carbeen (selected from the High-vigour cross at Glen Innes) to be superior to other oat varieties for tolerance to acid soils and aluminium toxicity.

Table 3.11 Effect of a single grazing, grain recovery, total yield and grain protein (%) on a range of oat cultivarsa.

Cultivar

Species

Cut 1 (t/ha)b

Grain (t/ha)c

Total Yield (t/ha)

Protein (%)d

Moore

A.sativa x A.byzantina

0.207

3.615

3.822

12.2

Avon (101)

A.sativa

0.224

3.508

3.732

12.0

Swan

A.sativa x A.byzantina

0.230

3.070

3.300

12.2

West (213)

A.sativa x A.byzantina

0.273

3.010

3.283

12.6

Coolabah (105)

A.sativa

0.198

2.826

3.024

13.3

Cooba (22)

A.sativa

0.143

2.542

2.685

15.3

Cassia (103)

A.sativa

0.230

2.281

2.511

14.3

Carbeen (19)

A.byzantina

0.166

2.341

2.507

14.2

Stout (212)

A.sativa

0.326

1.967

2.293

15.8

Saia (60)

A.strigosa

0.104

1.861

1.965

19.2

LSDe

-

0.112

0.538

-

-

a Trial conducted in South Australia in 1980 and reported by Craig and Potter (1983). All yields expressed in dry matter; b One pasture cut only was taken; c Grain yield after one grazing; d Protein content of grain harvested; e Least significant difference (t/ha).

Table 3.12 Effect of two grazing cuts on grain recovery and pasture yields on a range of oat cultivarsa.

Cultivar

Cut 1 and 2 (t/ha)b

Grain Yield
(t/ha)c

Total Yield
(t/ha)

Volumetric Weight
(kg/hl)

Grain weight
(g/1000 seed)

-2mm fraction
(%)d

Growth Habite

Carbeen (19)

1.391

3.227

4.618

44.0

34.8

9.9

3

Swan

1.477

2.195

3.672

49.0

45.0

4.2

7

Moore

1.252

2.321

3.573

47.1

42.0

5.4

8

Coolabah (105)

1.203

2.133

3.336

44.1

32.8

21.5

6

Cooba (22)

1.252

1.802

3.054

45.5

31.8

18.5

4

West (213)

1.317

1.534

2.851

47.8

36.3

10.0

8

Avon (101)

1.476

1.346

2.822

43.9

37.2

12.6

7

Cassia (103)

1.071

1.529

2.600

46.9

33.2

24.3

7

Stout (212)

1.315

0.850

2.165

46.0

35.8

9.5

7

Saia (60)

0.518

1.426

1.944

52.1

19.5

86.8

7

LSDe

0.445

0.538

-

-

-

-

-

a Trial of the same 10 varieties subjected to 2 grazings and grain recovery (Craig and Potter, 1983); b Sum of dry matter yields from 2 grazing cuts; c Dry matter grain recovery yield after 2 grazing cuts; d w/w (%) of grains passing through a 2mm screen; e Growth habit score on 1 to 10 scale where 1 = prostrate and 10 = erect; f Least significant difference.

Table 3.13 Dry matter of pasture and grain recovery trial, Gunning, NSW (1999)a.

Cultivar

Origin (oats)

P cut 1
(t/ha)

P cut 2
(t/ha)

Grain recovery (t/ha)

Blackbutt (11)

Glen Innes

3.49

1.46

3.70

Nile (209)

Tasmania

4.00

1.33

3.10

Maiden (Triticale)

 

4.20

1.48

2.62

Eurabbie (Oats)

Temora

4.17

1.37

1.80

Tennant (Wheat)

 

2.87

1.39

2.55

SDb

 

0.65

0.26

0.50

CV (%)c

 

10.72

12.65

14.51

Grazing date

 

11th June

20th August

 

a From Powell (2000). The above trial was sown on 1st April, 2000 and was harvested on 22nd December; b = significant difference; c = coefficient of variation.

Table 3.14 Grain yields from competing cereal crop trial conducted in New Englanda.

Crop

Variety

Yield Dry Season
(t/ha)b

Yield Wet Season
(t/ha)c

Oats

Acacia (1)

1.743

3.289

Oats

Algerian (3)

1.617

2.237

Oats

Fulghum (27)

0.983

-

Oats

Lampton (56)

-

2.930

Winter Wheat

Winglen

1.268

2.111

Winter Wheat

Cel. x Ten. D

1.268

2.804

Wheat

Celebration

0.951

1.544

Wheat

Lawrence

0.666

-

Barley

Abyssinian

1.141

2.268

Barley

Trabut

0.824

2.066

Barley

Pryor

0.666

2.804

a Trials under dry (1953) and wet (1954) conditions; b Trial conducted in 1953 at New England Research Station at Glen Innes; significant difference = 0.254 t/ha (standard deviation=13.7%); no grazing; sowing date was 10 April 1953; c Trial conducted in 1954 at New England Research Station at Glen Innes; significant difference = 0.781 t/ha (standard deviation = 21.8%); no grazing; sowing date was 11 May 1954.

Table 3.15 A continuous grazing (P) and grain recovery (pG) trial in Central NSW; F34 generation testing of High-vigour varities (1990) at Blayneya.

Cultivar (no.)

P t/hab

pG t/hac

t/had

Carbeen (19)
Blackbutt (11)
Birch II (W)
Empat (T)
Cooba (22)
WB135 (B)
Birch 41 (W)
Rosella (W)
Osprey (W)
Owlet (W)
M5291 (W)
Concort (R)
SD
CV (%)

2.32
2.16
1.63
1.48
2.55
2.29
1.85
1.91
1.68
1.58
1.08
0.93
0.46
14.6%

2.62
2.76
3.03
2.94
1.71
1.49
1.87
0.80
1.02
0.79
0.67
-
0.70
18%

4.94
4.92
4.66
4.42
4.26
3.78
3.72
2.71
2.70
2.37
1.75
0.93
-
-

a Sowing date: 5.3.90; harvested: 7.1.91; growing season: 308 days; rainfall 820 mm. W = wheat; T = triticale; B = barley; R = ryegrass (measure of pasture growth). NSW Department of Agriculture trial conducted at Blayney (cool climate) was sown into excellent moisture and tilth at seeding rates of 70 kg wheat, 100 kg oats, 80 kg barley, 90 kg triticale, 25 kg/ha Concord ryegrass. Fertilizer was 62 kg/ha urea pre-sowing + 110 kg/ha DAP at sowing = 48 kg N + 22 kg P/ha. b Pasture cut taken on 9.5.90, then continuous hard grazing to 19.6.90; c Grain recovery since 19.6.90. No pasture cut taken on 19.6.90; d Total of b + c, not total biomass (Gammie, 1990).

In the 1969 New England trials (Table 3.9), only Algerian, Coolabah and Fulghum were not significantly superior to winter wheat for 4 successive pasture cuts. P4315 and Abyssinian barley were the highest yielders for 2 grazings and grain recovery. The barley would not have withstood 4 grazings, as proven by other trials. In both trials, P4315 was the top yielder, followed by Blackbutt oats, its sister line from the High-vigour cross of 1957.

In the warmer climates of the Western Plains of Central NSW, all oats were significantly superior to winter wheats for first, second and total pasture cuts in a dry winter, 1964 at Condobolin (Table 3.16). For grain recovery, the Temora line, VRBurke (W4464) gave the highest yield, which was significantly superior to that of Winglen winter wheat but not Windebri. In the grain only section of this trial, W4464 and Avon oats were significantly superior to both winter wheats. Bundy was not inferior to the best winter wheat yields and was significantly superior in grain recovery, and in the grain only trial, to Belar, which it was intended to replace as an early mid-season oat with greater frost resistance and equal milling quality (Guerin, 1965). The yellowish brown colour of the grain, however, was not as acceptable for milling as the creamy brown grain of Belar. The better grazing yields of Cooba and its improved milling traits explain why Cooba replaced both Belar and Bundy. Summer rainfall climates adversely influence grain colour in most seasons. Millers therefore buy brighter coloured oat grain grown in the drier summer climates.

Carbeen was tested by Craig and Potter (1983) in South Australia. There it was the only variety not to suffer reduction in grain yields when grazed twice. Under severe winter conditions, however (Tables 3.11 and 3.12), Blackbutt proved to be the most productive oat for total yields. This higher productivity of Blackbutt amounts to an extra tonne when sowing is in early March rather than in late March. Associated with the extra yield is an increase in the protein content. The dry matter pasture yields and the grain recovery yields may be taken to be equal in energy value but the herbage dry matter would have a protein equivalent of 15, or twice that of oat grain, according to Robinson (1949). This is important for lactating cows or ewes, and for growing high quality fat lambs. The management of oat pasture requires knowledge, skill and supplementation with native pasture or dry feed at night time, for sound animal husbandry. The new High-vigour oats are greatly superior to wheat, rye and barley for biomass and protein yields. Winter wheat is too slow growing, as found also by Dann et al. (1977) at Canberra. Barley and Winter Rye have been excluded from the analysis of means (Table 3.9) of the early March sowing. The former was too frost susceptible and the latter too low in productivity for this environment. They are not suited for the heavy grazing required for high protein yields.

Table 3.16 Effect of two grazing cuts and grain recovery (Site 1) and grain only (Site 2) on a range of oat cultivarsa.

Variety

Site 1 (t/ha)

Site 2
Grain Only (t/ha)

Cut 1

Cut 2

Total Cut

Grainb

Avon (101)

0.73

0.88

1.59

1.38

3.32

Belar (9)

0.54

0.74

1.28

0.97

2.20

Bundy (15)

0.44

0.68

1.12

1.37

2.55

Cooba (22)

0.46

0.87

1.33

1.41

2.33

Kent (52)

0.84

0.85

1.69

1.10

2.35

VR Burkec

0.46

0.76

1.22

1.54

3.29

Windebrid

0.30

0.44

0.74

1.47

2.30

Winglend

0.39

0.48

0.87

1.23

1.95

SD

0.04

0.04

0.05

0.18

0.30

CV (%)

16.2

15.1

10.1

11.4

12.5

Cutting datee

105

160

-

-

-

a Site 1-sowing date: 24 March 1964; 4 replications; conducted at Condobolin, NSW; Site 2-sowing date: 5 May 1964; 4 replications; conducted on Mr.C.Grady’s farm at Trundle, NSW for grain only. All yields are for dry matter; b Grain yield after 2 grazings; c Early maturing line (W4464) bred at Temora, NSW; d Winter wheat varieties; e Days after sowing.

Figure 3.7 The Author (left) shows greater damage to Algerian from a combination of frost and grazing pressure than that to Klein 69B the Argentine oat, which showed excellent frost resistance and grazing recovery almost equal to Blackbutt. Further images of the grazed plots at Hawkesbury Agricultural College trials in Richmond NSW in 1966, are presented in Appendix B

Figure 3.8 A comparison of the five selections from the High-vigour cross for total biomass yield (P + pH) with conventionally bred cultivars at Hawkesbury Agricultural College, Richmond, NSW (1966).

Figure 3.9 A comparison of a standard cultivar, Algerian, with five selections from the High-vigour cross, with 5 separate pasture cuts at Hawkesbury Agricultural College, Richmond, NSW (1966). The extent of the grazing is shown in individual plots within the trial presented in Appendix B.

<3.9a here>

Figure 3.10 The Author at Temora Agricultural Research Station taking notes near seed increase blocks. Blackbutt oats is the hardiest of the High-vigour oats, combining high yields with frost resistance (Top); Mugga, also bred by the Author before his High-vigour cross, is the hardiest of the oats tested in Glen Innes NSW, with equivalent hardiness to winter wheat (Centre). P4315, like Blackbutt, was also from the same High-vigour cross (Bottom).

Recommendations for extension

With the much higher and more stable yields of the new bulk varieties (Tables 3.3, 3.4 and 3.5), four years of testing instead of the usual 7 years would therefore be sufficient for cultivar release. This would be the case especially if the number of testing sites could be increased. Instead of the usual 15 years under the pedigree system, which could be run concurrently, the time from cross to farmer can be halved to 6 years for F3 bulks and 8 years for F4 directed bulks. New possibilities are opened up by this rapid breeding technique for producing dual-purpose oat cultivars. For NSW oat research programs to be attractive to funding, it will probably need to replace the popular variety Cooba with a variety that yields at least 20% higher.

The F3 bulk, P4315, tested from 1960 to 1976, was at times up to 100% higher in yield than Cooba but lacked milling suitability. It may soon be that this stipulation of millibility will be waived by the NSW Department of Agriculture, allowing such potential cultivars to be released to farmers. As well as P4315, there is a millable F4 directed bulk, P4318, which is also tolerant to barley yellow dwarf virus (BYDV), as is P4315. There could be little, if any, advantage in releasing a high yielding F3 bulk to a farmer who is interested in growing oats for grain only. On the other hand, farmers who are in need of supplementing their winter pastures (Crofts 1966), and who practise optimum soil and crop management (Guerin 1961) stand to gain significantly. Supporting the latter type of farmer would increase Australia's relatively low average oat yields (approximately 1.4 tonnes/ha), bringing them closer to the yields reported in this chapter. The model farmer will extend both seed and cultural knowledge to make long-term profits.

A further recommendation based on the results of the NSW Department of Agriculture oat breeding and testing program, i.e. the results of which are presented in this chapter, is that F3 bulks and F4 directed bulks should be maintained indefinitely, not alone as gene banks similar to Suneson’s composites (Allard and Hansche 1964), but also to monitor yield changes, over time, relative to all check varieties, including Algerian, Fulghum and Cooba.

Conclusions

This study highlights several important considerations for plant breeding. Firstly, The important lesson from Isolection breeding is to aim for close (not distant) crossing within the same ecospecies or morphological type, like winter oat x winter oat or spring type x spring type, rather than winter x spring type crosses. This concentrates the multiple genes needed for each type. Wide crossing within the hexaploid oats (or wheat) requires backcrossing in order to regain the ecotype, while the full yield potential being sought is not regained. As well as concentrating together the multigenes required for a winter oat (or a spring oat), the Isolection system also enables the rapid breeding of new varieties. Thus, from the High-vigour cross of 1957, the Author was able to recommend the release of both P4319 and P4315 as early as 1966. However, only P4319 was released and it was subsequently named Blackbutt in 1974.

Secondly, plant breeders should select as many plants as possible in the F2 to retain as much hybridity as possible, leading to homeostasis and versatility, as compared with F6 selected inbreeds, which show much more environmental variation. This is important in the case of oats, where cross-pollination is only 0.5% as compared with 5% in wheat and triticale. Nevertheless, James Carroll, the Author’s predecessor, maintained that fixity is never finalised and this is certainly the case with landraces like Algerian and Fulghum (as discussed in Chapter Two). Early, not later, generation selection is suggested by the Mendelian diagram for a trihybrid or three factors.

Thirdly, the results of this study indicate that heavy grazing, that is 4 or more pasture cuts, are essential to assess true dual-purpose capacity of oat varieties.

Finally, the results of NSW-wide biometrically designed and analysed yield trials have strongly supported the principle of the Isolection breeding system, which may be stated as follows: The continuing ability to observe and select new varieties of cultivated crops depends on isolating single (individual) plants with optimum space and nutrient status in the early generations after the cross and situated in the locality for which the crop is being bred. While the principle of Isolection is essential to pin-point and select new varieties, yield per unit area rather than yield per single plant is the ultimate goal and this requires statistically sound replicated yield trials in order to determine the highest yielding commercial variety of oats for the farmer. The best dual-purpose oats now derive from the High-vigour cross which has produced Blackbutt and Carbeen. The results of this oat breeding and testing has proved the advanced state of competence in oat breeding, testing and production that has been achieved in Australia.

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5 Personal communication (2005).

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