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Grain yield of Heritage wheat varieties in South Australian Mallee, 2001.

Richard Saunders

Rural Solutions SA, Loxton Research Centre, Email saunders.richard@saugov.sa.gov.au

Abstract

In general the rate of increases in yield and water use efficiency in the low rainfall regions has been less than that recorded in the medium and high rainfall zones. While higher yield potential of modern, short strawed-varieties is widely recognised, the yield advantage of these lines is often much less in low rainfall environments. The aim of this work was to assess the genetic gains achieved under the harsh environment of the mallee region of South Australia. Twenty eight wheat varieties, of historical significance to grain production in Australia, and in particular the South Australian Murray Mallee (Heritage varieties), were compared with two modern Australian wheats, Yitpi and RAC892 (syn. Stylet) in a series of small plot trials in 2001. The experiment was repeated at Minnipa on the Upper Eyre Peninsula. The modern variety, Yitpi, produced the highest yields across all Murray Mallee sites (2.38 t/ha). The oldest variety, Ward’s Prolific (1882), yielded 68% of Yitpi. Results for other Heritage varieties compared to Yitpi include Steinwedel (1884) 58%, Early Gluyas (1894) 68%, Federation (1901) 72%, Caliph (1912) 73% and Halberd (1969) 91%. The Heritage varieties ranged from 57 % to 91 % of Yitpi. The rate of grain yield increase was7.4 kg/ha/year in the Murray Mallee, and 7.1 kg/ha/mm at Minnipa. The improvements in yield has led to improvements in water use efficiency (WUE), with the WUE of modern variety Yitpi being 40% greater than the WUE of Federation. These experiments have illustrated contribution of wheat breeding to yield improvements to yield and water use efficiency in low rainfall areas. This has been due to improved adaptation to the climate; seed borne diseases; soil and foliar diseases; nutrient deficiencies and sub-soil constraints.

Key Words

Breeding, history, water use efficiency, plant breeding

Introduction

Compared to the medium and high rainfall zones of south eastern Australia, increases in wheat yields and water use efficiency in the low rainfall regions of South Australia have been modest (Hamblin and Kyneur 1993, Black 2004, Blumethal and Walcott 2006). For example, Hamblin and Kyneur’s analysis showed that between 1950 and 1991, average yields in South Australia increased by between 4 and11 kg/ha/yr, with yield improvements significantly less in the low rainfall areas of the State.

The long-term increases in yield have been associated with improvements in agronomy and in the yield potential of new varieties. There is little information on the impact of genetic improvement on the yield of wheat in low rainfall environments. In a study in Western Australia using 28 historic varieties, Perry and D’Antuono (1989) showed an increase in grain yield with the year of introduction of 5.8 kg/ha/year. In comparison in a medium rainfall area in South Australia, Vandeleur and Gill (2004), estimated an average yield increase of 15.5 kg/ha/yr when rust was not a limitation to yield.

The primary aim of the cereal breeder has been and remains greater yield and/or quality (Perry and D’Antuono 1989) Improving the adaptation of wheat to local conditions was recognised early; for example, Prof. Custance of Roseworthy Agricultural College in the 1880’s was ‘…convinced that early maturity and drought tolerance were essential agronomic qualities for the local environment’ (Simmonds 1989). Subsequently, considerable effort and money has been expended in the quest for better adapted varieties for South Australian climatic and edaphic conditions, as well combating serious foliar and root pathogens. The aim of this work was to assess the level of genetic gain for wheat in the mallee environment.

Methods

In 2001, a series of trials was conducted at eight Mallee sites and one Eyre Peninsular site. Twenty eight historically-important varieties were evaluated against two recently released South Australian lines. The lines were selected for inclusion in these trials because of their important historic contribution to the wheat industry in the SA Mallee (Pearson 1957). Trials were planted as unreplicated small plot trials (10 m x 1.6 m plots) with Yitpi as the check plot throughout. Murray Mallee yields were analysed by Colleen Hunt (BiometricsSA) using spatial Multi Environment (MET) analysis. The experiments were sown in mid June at each of the sites using standard seeding and fertiliser rates. Rainfalls at the sites ranged from 248 mm to 416 mm with and average of 309 mm. There was no recorded yield limiting factors such as frosts, foliar or root diseases for most of the sites. Growing season (April-October) rainfall (GSR) was recorded and used to estimate the water use efficiency (WUE) of the crops. It was assumed that soil evaporation was 90 mm and the variety WUE was estimated as: (grain yield)/ (GSR-90).

Results

Average yields ranged from 1.349 t/ha (Steinwedel) to 2.492 t/ha (RAC 892). The modern varieties were consistently higher yielding than the Heritage lines and the oldest varieties generally ranked consistently low across all sites. RAC 892 and Yitpi ranked first or second across all sites. The next best varieties were Halberd (1969) and Insignia (1946). Varieties performing consistently poorly were Steinwedel (1884), Comeback (1901) and Pusa (1916). The variety rankings for Murray Mallee and Minnipa sites were very similar. The average rate of yield increase among these varieties was 7.2 kg/ha/yr, which was the same as that recorded at Minnipa. (Fig. 1, 2). The heritabilities were high, often exceeding 70%. A frost occurred at Geranium in October, which explains why Geranium had the lowest yield and WUE. Yield variability at this site, assessed by the coefficient of variation (cv%), was also high and the heritability was low (Table 2).

The comparative WUE figures for Yitpi and Federation are presented in Table 2. Yitpi consistently had a higher WUE figures than Federation. At no site did Federation achieve a WUE greater than 18 kg/ha/mm. Minnipa’s WUE results were similar to those from the Murray Mallee for both Yitpi and Federation.

Discussion

One of the problems of comparing the yields of an historical set of varieties is that old and new varieties are grown under modern farming methods, whereas management practices have changed significantly in 100 years. For example, in 1907 six wheat varieties were compared at Loxton (Angus 1908). The experiment was sown on June 12, 1907 at a sowing rate of approximately 50 kg/ha with 56 kg/ha of phosphate. The grain yield of Federation was 1.01 t/ha (15 bushels per acre). The annual rainfall in 1908 was 286 mm, of which 219 mm fell between March and October. The estimated WUE was about 8 kg/ha/mm, which is less than that estimated for the current trials. However, heavy frosts during September reduced the yield by about 404 kg/ha which would have provided a WUE of about 11 kg/ha/mm. In comparison, Federation wheat sown at the Mallee sites in early to mid June in 2001 yielded an average of 1709 kg/ha with an average WUE of 12 kg/ha/mm (Table 2), which is the same as that achieved under the farming systems of 1907. This is somewhat surprising as it suggest that changes in farming practices have had little or no effect on WUE.

As expected, modern Australian wheat varieties yielded more than a range of Heritage Australian wheats and there appears to have been a gradual improvement in yield from wheats released in the 1800s to the latest line RAC 892. The rates of yield improvement in the Mallee and the other low rainfall site on the Upper Eyre Peninsula were the same, but were greater than the estimated yield gains from Western Australia, but both were much less than genetic gains estimated in a higher rainfall region (Vandeleur and Gill 2004). Roseworthy is a high rainfall site (329 mm GSR per annum and averaging 331 mm GSR over the three years of the trials). The Mallee is a low rainfall zone where average annual and GSR rainfall for Loxton SA is 273 and 190 mm respectively. Using Vandeleur and Gill (2004) data it is possible to compare yields from the two zones. Calculating a per cent yield gain per year using the rate of increase (kg/ha/yr) from 1880 in the case of Mallee and Minnipa, and 1860 from Roseworthy, the Mallee and Minnipa trials show gains of 0.50 % and 0.43 % per year respectively, whereas the Roseworthy trials indicate an average gain (years 1999 and 2001) of 1.21 % per year. The comparison is stark: not only are absolute yield gains lower in the low rainfall Mallee environments but relative yield gains are too. Whilst there has been significant progress in wheat breeding over time, the low rainfall zones of South Australia are lagging behind higher rainfall areas in both real and relative yield gains.

The conclusion from these trials, based on yield alone, shows there has been significant progress in wheat breeding over the last 100 years. South Australian growers have benefited from wheats bred for better adaptation to South Australian soils, with improved disease and pest resistance, tolerance to soil toxicities and deficiencies and finally the unchanging seasonal factors such as rainfall and poor seasons. The increase in wheat yields with time is further demonstrated by the increased water use efficiency of modern varieties over the Heritage lines. In the Murray Mallee Yitpi was 42% more efficient in its use of water for grain

Table 1 Yield, rank, and % Yitpi yield of varieties across eight South Australian Mallee sites and a site at Minnipa, South Australia.

Variety

Year
released

Origin

Grain yield

     

SA Mallee sites

Minnipa

   

t/ha

rank

% Yitpi

t/ha

rank

% Yitpi

Bencubbin

1929

WA

1.961

6

82

2.192

5

85

Caliph

1912

RAC

1.747

17

73

1.952

15

76

Claymore

1956

RAC

1.998

5

84

2.143

6

83

Comeback

1901?

Farrer

1.349

30

57

1.630

27

63

Dirk_48

1949

SA

1.884

10

79

1.906

22

74

Early_Gluyas

1894

SA

1.618

23

68

1.884

24

73

Federation

1901

Farrer

1.709

19

72

2.039

10

79

Ford

1916

RAC

1.730

18

73

1.900

23

74

Gabo

1945

NSW

1.939

8

81

2.003

13

78

Glaive

1966

RAC

1.948

7

82

2.013

11

78

Halberd

1969

RAC

2.168

3

91

2.429

3

94

Hard_Federation

1914

NSW

1.564

27

66

1.963

14

76

Insignia

1946

Vic

2.098

4

88

2.366

4

92

Javelin_48

1949

WARI

1.786

15

75

1.924

18

75

Kite

1973

NSW

1.868

11

78

2.109

8

82

Majestic

1900?

SA

1.649

22

69

1.922

19

75

Marathon

1939

SA

1.618

24

68

1.920

21

75

Pusa

1916

India

1.461

28

61

1.601

28

62

RAC_892

2002

RAC

2.492

1

105

2.847

1

110

Ranee

1924

Vic

1.707

20

72

2.069

9

80

Ridley_48

1949

WARI

1.835

13

77

1.922

19

75

Sabre

1952

RAC

1.845

12

77

1.882

25

73

Scimitar_48

1949

WARI

1.825

14

77

2.009

12

78

Steinwedel

1884

SA

1.375

29

58

1.468

30

57

Sword

1923

RAC

1.771

16

74

1.930

17

75

Ward's_Prolific

1882

SA

1.610

25

68

1.838

26

71

Warigo

1941

WARI

1.666

21

70

1.941

16

75

Wongoondy

1948

WA

1.896

9

80

2.135

7

83

Yandilla_King

1907

SA

1.591

26

67

1.488

29

58

Yitpi

1999

WARI

2.383

2

100

2.577

2

100

site mean

   

1.803

2.000

No. of sites

   

8

1

   

WARI = Waite Agricultural Research Institute, SA; WA = Western Australia; Farrer = Farrer Institute; SA = South; Australia; NSW = New South Wales; RAC = Roseworthy Agricultural College; Vic = Victoria

Table 2 Yield, coefficient of variation (CV %), heritability (%), annual and growing season rainfalls (GSR) and water use efficiencies (WUE) of Yitpi and Federation wheats across the eight sites.

Ave Yield

CV

Heritabiility

Rainfall (mm)

WUE (kg/ha/mm)

(kg/ha)

(%)

(%)

Annual

GSR

Yitpi

Federation

Difference

Geranium

1.392

29.7

2.9

416

296

9

6

2

Lameroo

2.020

2.7

93.5

366

255

17

12

5

Nangari

1.919

8.1

69.5

264

199

23

17

6

Pinnaroo

2.616

3.0

91.8

327

254

21

15

5

Tepko

1.363

7.0

87.3

308

228

16

9

7

Waikerie

1.763

12.2

18.7

248

191

21

17

4

Wanbi

1.424

6.6

82.8

293

219

15

10

4

Wunkar

1.928

3.2

90.1

250

195

24

17

7

Mean

1.803

309

230

17

12

5

Minnipa

2.000

2.5

354

267

15

12

3

Figure 1 Mean grain yield (t/ha) for 30 wheat cultivars at eight sites in the Murray Mallee, plotted versus year of introduction. Y axis is grain yield in t/ha and X the years since 1884.

Figure 2 Mean grain yield (t/ha) for 30 wheat cultivars at one site at Minnipa, plotted versus year of introduction. Y axis is grain yield in t/ha and X the years since 1884.

production than Federation, producing on average an extra 5 kg/ha of grain per millimetre of effective rainfall. At Minnipa comparing the same varieties there was 25% increase in WUE producing an extra 3 kg/ha of grain per millimetre of effective rainfall.

Australian wheat breeders are currently using conventional breeding and/or marker assisted selection techniques targeting single genes. Kuchel (2008) states genomic analysis of wheat should give breeders better understand of the genetic basis for drought stress adaptation. Combined with an effective selection system genomic analysis will hopefully lead to greater rates of genetic gain for drought tolerance and therefore provide wheats better suited to the South Australia Mallee cropping regions.

References

Angus W (1908) Agricultural Experiments (1907). J. Agric, South Australia, Number 39, February 1908.

Black I (2004) The regional impact of research and extension in increasing the productivity of South Australian broadacre agriculture: results and recommendations from econometric analyses. South Australian Research and Development Institute: Adelaide.

Blumethal M and Walcott, J. (2006) Strategic Approaches to Growing More Grain. Science for Decision Makers Seminar Series, Bureau of Rural Science. http://www.daff.gov.au/brs

Ferns GK, Fitzsimmons RW, Martin RH, Simmonds DH and Wrigley CW (1975) Australian Wheat Varieties. Identification according to Growth, Head and Grain characteristics, CSIRO.

Hamblin A and Kyneur G (1993) Trends in wheat yields and soil fertility in Australia, Bur. Res. Sciences.

Kuchel H (2008) Breeding for drought tolerance, GRDC Update, Adelaide, February 2008.

Pearson FB (1957) Choosing wheat varieties: Department of Agriculture, South Australia. Leaflet No. 9/57

Perry MW and D'Antuono MF (1989) Yield improvement and associated characteristics of some Australian spring wheat cultivars introduced between 1860 and 1982. Australian Journal of Agricultural Research 40(3) 457 – 472

Simmonds DH (1989) Wheat and Wheat Quality in Australia, CSIRO.

Vandeleur RK and Gill GS (2004) The Impact of plant breeding on the grain yield and competitive ability of wheat in Australia. Australian Journal of Agricultural Research 55: 855-86

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