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Responses of bread and durum wheat to agronomic practices in Western Australia

Shahajahan Miyan1 and Wal Anderson2

1 Centre for Cropping Systems, Department of Agriculture and Food, Northam, WA 6401; Email: smiyan@agric.wa.gov.au
2 Department of Agriculture and Food, 444 Albany Highway, Albany, WA 6330; E-mail: wanderson@agric.wa.gov.au

Abstract

A field experiment was conducted in 2004 to determine the optimum combination of sowing time, seeding rate and nitrogen (N) rate for durum wheat (Triticum turgidum L. ssp. durum) compared to bread wheat (Triticum aestivum L.) on a clay loam soil at Mukinbudin in Western Australia. Grain yield and grain protein were measured. There was no significant response in grain yield to the application of 40 kg N/ha of N fertiliser at seeding but there was a significant increase in grain protein concentratiion, by 4.2 % compared to 0 kg N/ha applied at seeding. On average, grain yield of durum wheat cultivars yielded 4.3% less than the bread wheat cultivars. Despite the lower yield of durum wheat cultivars, gross return was higher than that of bread wheat cultivars. Time of sowing did not affect the grain yield or grain protein.

Key Words

Time of sowing, nitrogen rate, grain yield, grain protein

Introduction

The climatic conditions in the wheat belt in Western Australia (WA) are very similar to those in the Mediterranean basin, the traditional home of durum wheat (Triticum turgidum L. ssp. durum) production, with winter dominant rainfall and mild winter temperatures. Interest in producing durum wheat in WA arose because of its high value relative to bread wheat (Triticum aestivum L.) and its potential suitability for the local climate.

Durum wheat is used in the production of pasta and couscous. The consumption of pasta is stable in areas where there has been a long history of durum cultivation (eg. Mediterranean basin) and increasing in areas where cultivation and crop improvement has been more recent (eg. North America). The prices for durum wheat are consistently greater than those for bread wheat of similar protein percentage (Australian Wheat Board, 2000). The increasing demand and the high prices mean the long term outlook for durum wheat is favourable (Impiglia, 2000).

One of the major concerns for durum growers in WA is grain quality as defined by the protein concentration in the grain. A grain protein concentration of 13% is required to qualify for premium grade payments. The inherent soil fertility is too low to produce high grain protein in most seasons so rotation with legumes, and/or high application rates of nitrogen (N) fertiliser will probably be required to improve grain protein percentage. It has been long recognised that adoption of grain legumes in farming systems can significantly increase cereal yields in the following year (Edward and Haagensen, 2000). The specific benefits of growing leguminous crops in a rotation include weed and disease management, soil structural benefits, erosion control and nutrition for following crops (Chatel and Rowland, 1982). The aim of the study was to examine the importance of sowing time, seeding rate, and nitrogen rate on grain yield and quality of bread and durum wheats.

Methods

A field experiment was conducted at Mukinbudin (284mm average annual rainfall) in 2004 comparing five durum (Arrivato, Bellaroi, Kalka, Tamaroi, Wollaroi) to four bread wheat cultivars (EGA Bonnie Rock, Carnamah, Tamarin Rock, Machete). Each cultivar was sown at two times of sowing, two nitrogen rates (0 and 40 kg/ha of N) and three seeding rates (50, 100 and 200 seeds/m2) in a clay loam soils with soil pH 6.6 (CaCl2). The experiment was sown after a field pea crop. Time of sowing (TOS) 1 was 28th of May and TOS2 was 10th of June 2004. Seeding rates were calculated using percentage germination and mean 1000 grain weight to achieve the target plant density per square meter. Individual plot size measured 1.44 m by 20m. All N was applied as urea as seeding. Weeds were controlled using appropriate pre-and post emergent herbicides.

Measurements

Soil samples were collected prior to seeding (0-10 and 20-30 cm soil depth) and analysed for pH, EC, organic carbon and major elements (Table 1). Plant density was estimated by counting plant numbers in two rows each of 1m length in each plot. The trial was harvested with a small plot header and a sub-sample was taken for grain quality analysis. Grain yield (t/ha) and, grain protein (% by near infrared reflectance calibrated against the standard Kjeldahl test) were measured and gross return ($/ha) was calculated for all plots. Gross return was calculated using prices based on protein (%) and screening (%) for both bread and durum wheat cultivars (Australian Wheat Board, 2000). Analysis of variance was carried out using Genstat for Windows 10th edition.

Table 1. Chemical characterisation of the soil at Mukinbudin in 2004

Depth
(cm)

pH

P
(mg/kg)

Org.C
(%)

K
(mg/kg)

NH4-N
(mg/kg)

NO3-N
(mg/kg)

EC
(mS/m)

0-10

6.6

27

0.95

602

8

6

0.06

20-30

7.9

12

0.79

325

4

14

0.35

Results

Pre-sowing rainfall (cumulative from January 2004) was 73 mm and 124 mm when the crops were sown on 28 May and 10 June, respectively. Growing season rainfall from April to October was 233 mm. Low rainfall in October and November was associated with low yields and high screenings in both durum and bread wheat cultivars.

Results from this trial show that there was no significant response of grain yield due to the application 40 kg N/ha at seeding (Table 2). However, the addition of N fertiliser resulted in 4.0 % higher grain protein concentration than the unfertilised control. Irrespective of the N fertiliser treatment, grain protein levels were above 13% for both durum wheat and bread wheat cultivars. The application of 40 kg N/ha resulted in the highest grain protein levels, which will attract the highest premium price. Previous studies on hard grain bread wheat have reported that grain protein exceeded 13% from crops grown on friable red brown earth soil in a medic or field pea rotation (Anderson et al 1995). Time of sowing did not affect the grain yield or grain protein (Table 2).

Table 2. Results of the Analysis of Variance. Averages across treatments are given. The least significant difference (LSD) is given at p<=0.05.

Experimental factor

Grain Yield
(t/ha)

LSD
(P<0.05)

Grain Protein
(%)

LSD
(P<0.05)

Nitrogen fertiliser

        

0 kg N/ha

1.62

ns

14.4

0.4

40 kg N/ha

1.56

  

15.0

  

Time of sowing

        

28 May 2004

1.57

ns

14.6

ns

10 June 2004

1.61

  

14.7

  

Seeding rate

        

50 seed/m2

1.49

0.11

14.7

ns

100 seeds/m2

1.59

  

14.7

  

200 seeds/m2

1.69

  

14.6

  

Wheat species

        

Durum wheat

1.56

ns

14.8

ns

Bread wheat

1.63

  

14.5

  

The performance of the cultivars individually (averaged over sowing times and N rates) are shown in the Table 3. The highest yielding durum wheat cultivar Wollaroi yielded 4.13 % less than the highest yielding bread wheat cultivar EGA Bonnie Rock and Carnamah, but the differences in this experiment were not significant. Although the yields and hence the gross returns were not significantly different between bread and durum wheats the gross return for durum was greater, a result found previously for crops grown in Western Australia (Impiglia 2000). This illustrates the capacity of durum to achieve equal or better returns than bread wheat where soil and rotational conditions suit. Previous experience has been that Wollaroi is slightly better adapted than Tamaroi in low rainfall areas (A. Impiglia, pers comm.)

Table 3. Grain yield, grain protein and gross return at Mukinbudin, 2004. Averages across sowing times, seeding rates and N fertiliser rates are given. The base price for durum wheat was $262/tonne (at 13% protein and 5% screenings) and for bread wheat was $232/tonne (at 11.5% protein, 5% screenings).

Cultivar

Grain Yield
(t/ha)

Grain Protein
(%)

Gross Return
($/ha)

EGA Bonnie Rock

1.75

14.4

447

Carnamah

1.75

14.3

441

Tammarin Rock

1.53

14.6

383

Machete

1.51

14.7

385

Arrivato

1.46

15.3

402

Bellaroi

1.63

15.0

448

Kalka

1.56

14.7

429

Tamaroi

1.47

15.0

407

Wollaroi

1.69

14.2

464

LSD (P<=0.05)

NS

NS

NS

Conclusion

Sowing time, nitrogen fertilizer addition or wheat species did not significantly affect grain yield in this experiment. Grain yields were significantly increased at 200 compared to 50 seeds/m2 seed rate but the species responded similarly. Nitrogen fertilizer did increase grain protein in both bread and durum wheat. However, all grain protein levels were above 14% and the grain samples attracted premium prices. It is concluded that these results have provided further evidence that despite slightly lower yields of durum wheat the gross returns are likely to be greater than for bread wheat when the conditions of soil type, rotation and season are suitable.

References

Anderson WK, Crosbie GB and Lemsom K. (1995). Production practices for high protein, hard wheat in Western Australia. Australian Journal of Experimental Agriculture 35,589-595.

Australian Wheat Board (2000). Golden Rewards Launched. http://www.awb.com.au/

Chatel ,DL and Rowland LC (1982). Journal of Agriculture, Western Australia. 23:92-95

Edward A and Haagensen A (2000) In The Wheat Book, Bulletin 4443, Eds WK Anderson and JR Garlinge. pp. 109-130, Agriculture Western Australia.

Impiglia A (2000) Durum. In The Wheat Book, Bulletin 4443, Eds WK Anderson and JR Garlinge. pp. 272-292, Agriculture Western Australia.

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