Crop and Pasture Science Crop and Pasture Science Society
Plant sciences, sustainable farming systems and food quality
Crop and Pasture Science

Crop and Pasture Science

Volume 63 Number 7 2012

CP12062‘Haying-off' in wheat is predicted to increase under a future climate in south-eastern Australia

J. G. Nuttall, G. J. O'Leary, N. Khimashia, S. Asseng, G. Fitzgerald and R. Norton
pp. 593-605

Under a future climate for south-eastern Australia there is the likelihood that the combined effect of elevated carbon dioxide, lower spring rainfall and high temperature will increase haying-off in wheat crops, thus limit production. We used a simulation modelling approach and found in the semiarid cropping zones of Victoria, a 45% increase in the frequency of haying-off occurred when crops were sown near the historically optimal time (01-June), which translated to an 8% reduction in average yield. We found sowing earlier (01-May) reduced the impact of a future climate on haying-off, thus appears to be an important management strategy for maintaining wheat production in semiarid cropping regions into the future.

CP12183Pyramiding adult-plant powdery mildew resistance QTLs in bread wheat

B. Bai, Z. H. He, M. A. Asad, C. X. Lan, Y. Zhang, X. C. Xia, J. Yan, X. M. Chen and C. S. Wang
pp. 606-611

Powdery mildew is an important wheat disease worldwide. Pyramiding of minor resistance genes can be an effective approach for developing durable resistance to the disease. Twenty one lines carrying two-five resistance genes developed from two Chinese wheat cultivars Bainong 64 and Lumai 21, had significant effects on response to powdery mildew disease. Experienced breeders with a good knowledge of minor genes can achieve durable resisatnce by phenotypic selection, and selection by molecular markers will still require uniform field testing for powdery mildew and disease phenotype to validate the resistance. These results provided very useful information for pyramiding durable minor genes in wheat breeding programs.

Field pea is the second most important cultivated grain legume in the world. Pea weevil is the most damaging insect pest of field pea. Screening plants for pea weevil response is one of the challenges for plant breeders. We demonstrated that the caesium chloride density separation method is a useful tool for efficiently separating infested from uninfested seeds. We were able to introgress pea weevil resistance from wild pea into cultivated field pea and produce several pea weevil resistant lines following the selection method.

Australian wild mungbeans are a potential source of novel useful traits, especially ones that enhance their adaptation to the natural stresses they experience in the wild. We studied the inheritance of traits in hybrids between wild and cultivated mungbeans. Along with several other wild traits, perenniality and the absence of powdery mildew infection were qualitatively inherited, and so should be susceptible to selection during crop breeding.

The idea of grazing a canola crop during winter while still harvesting grain at the end of the season seems too good to be true. Pasture production during winter is low and canola can be grazed by livestock without reducing grain yield. Grazing canola removes the winter feed gap, increases potential livestock production while not compromising grain production on mixed farms.

CP12024Agronomic and economic evaluation of irrigation strategies on cotton lint yield in Australia

Davide Cammarano, José Payero, Bruno Basso, Paul Wilkens and Peter Grace
pp. 647-655

The increased competition for water requires irrigated cotton growers to re-assess their current management practices to maximise their profit per unit of water applied. Agronomic and economic evaluation of irrigation strategies found that irrigation should be aimed at maximising profit rather than yield. The amount of irrigation to apply depends on the growing season, agronomic management and prizes of input. The study shows that crop models can be useful tools to maximize profit and reduce environmental impact.

Many Australian legumes have adaptations to dry climates and may provide useful, drought-tolerant, perennial forage plants for agriculture in low rainfall conditions. Previous research has already identified useful agricultural traits in the Australian legume Cullen australasicum, but this paper also reveals useful traits and phenotypic variability in several other species of the Cullen genus. The results offer motivation for further collection and development of several Cullen species for use as perennial legume forages specially adapted to low-rainfall, Mediterranean-type climates.

CP12239Amelioration of root disease of subterranean clover (Trifolium subterraneum) by mineral nutrients

Tiernan A. O'Rourke, Megan H. Ryan, Tim T. Scanlon, Krishnapillai Sivasithamparam and Martin J. Barbetti
pp. 672-682

Both root disease and poor nutrition contribute to subterranean clover pasture decline. Application of a complete nutrient solution, potassium or nitrogen alone, decreased the severity of tap root disease by up to 45% and lateral root disease by up to 32%. Nutrient amendments offer an alternative and more sustainable approach to better manage root disease and increase productivity of pasture legumes where soils are inherently nutrient deficient.

The lack of a practical way of measuring dry matter losses (DML) of conserved forages is a constraint to assess hay and silage conservation efficiency. The paper presented a novel technique of predicting storage DML by changes in forage chemical composition. A Monte Carlo simulation was performed to validate the procedure and state the sample size needed. The success in developing a simple and economic way of measuring DML will assist in monitoring hay and silage practices and technologies.

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