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 67 Number 8 2016

CP16056Recent changes in southern Australian frost occurrence: implications for wheat production risk

Steven Jeffery Crimp, Bangyou Zheng, Nirav Khimashia, David Lyon Gobbett, Scott Chapman, Mark Howden and Neville Nicholls
pp. 801-811

Although Australia’s mean surface air temperatures, daytime maximum temperatures and overnight minimum temperatures have warmed, there has, somewhat paradoxically, been an increase in frost risk across much of southern Australia. Recent regional and localised changes in the frequency, timing and duration of minimum temperature extremes all show increasing risk. Over the last six decades, more frost events and longer frost season length have contributed to an increase in the potential for frost-related crop losses. This paper examines and quantifies the extent of the production risk changes for 65 sites across the Australian wheatbelt and shows how managing frost risk has become more challenging over the last two decades and will potentially remain so in the near future.

CP15331Rice-cold tolerance across reproductive stages

J. H. Mitchell, S. L. Zulkafli, J. Bosse, B. Campbell, P. Snell, E. S. Mace, I. D. Godwin and S. Fukai
pp. 823-833

Cold temperature stress at the reproductive stage can cause significant yield reductions in rice. Floral characteristics were examined in relation to spikelet sterility to determine tolerance mechanisms at flowering, with enhanced anther dehiscence identified as important. Identification of traits and QTLs associated with cold tolerance will provide useful tools to breeders to maximize efficiency of rice improvement and yield stability for cold temperature environments.

CP15338Variation in drought-tolerance components and their interrelationships in the core collection of foxtail millet (Setaria italica) germplasm

Lakshmanan Krishnamurthy, Hari Deo Upadhyaya, Junichi Kashiwagi, Ramamoorthy Purushothaman, Sangam Lal Dwivedi and Vincent Vadez
pp. 834-846

Foxtail millet, an arid crop, is ideal for the changing climate. Drought tolerance of this crop depended more on transpiration efficiency (TE) and harvest index (HI) than on total water use (T). Germplasm races offered specific choices for T, TE or HI selection.

CP16159Seeding rate and cultivar effects on canola (Brassica napus) competition with volunteer wheat (Triticum aestivum)

Deirdre Lemerle, David J. Luckett, Eric A. Koetz, Trent Potter and Hanwen Wu
pp. 857-863

Weeds are a major cost to canola production in Australia but herbicide control options are running out as resistance spreads. Crop competition using vigorous hybrid canola cultivars combined with crop densities of at least 40 plants/m2 is essential to avoid high levels of weed seed production and spread, and crop yield loss. Crop competition for weed control is another important tool for reducing weed impacts.

Scarce and expensive irrigation water needs to be used effectively. After the onset of root expansion, forage turnip yield increased in proportion to the amount of irrigation applied when the soil remained below field capacity. However, scarce irrigation should be applied between the onset of root expansion and approximately 8 weeks later, when the response to irrigation ( kg DM ha–1 mm–1) was greatest.

CP15184Shift in origin of plant nitrogen alters carbon and nitrogen assimilation during reproductive stages of soybean grown in a Mollisol

Y. S. Li, X. B. Liu, G. H. Wang, Z. H. Yu, U. Mathesius, J. D. Liu, S. J. Herbert and J. Jin
pp. 872-880

Understanding how reducing nitrogen (N) fertiliser application may affect origin of plant N in soybean is important to maximize fertilizer use efficiency. Using dual-labelling (15N and 13C) technique, the proportion of N origins in plant and C assimilation were quantified under two N levels. Greater photosynthetic C allocation to roots would greatly contribute to the alteration of N acquisition pattern when fertiliser N supply is reduced.

CP15241Effect of watertable depth and salinity on growth dynamics of Rhodes grass (Chloris gayana)

Sebastián Chiacchiera, Nicolás Bertram, Edith Taleisnik and Esteban Jobbágy
pp. 881-887

This experiment quantified the effects of the depth and salt concentration of the watertable on the growth dynamics and biomass accumulation of Rhodes grass. The presence of non-saline watertable at a depth of 25 cm produced a 5-fold greater biomass, quintupled the water consumption and presented groundwater use efficiency 30% higher and leaf blades 50% longer compared with deeper watertables.

CP16102Low-cost automated biochemical phenotyping for optimised nutrient quality components in ryegrass breeding

L. W. Pembleton, J. Wang, G. C. Spangenberg, J. W. Forster and N. O. I. Cogan
pp. 888-896

Quantification of forage quality is essential for the identification of elite genotypes in forage grass breeding. However, current methods are labour-intensive, low-throughput and cost-prohibitive for commercial breeding programs. An accurate high-throughput micro-plate-based protocol has been developed and validated, with the ability to simultaneously process and quantify WSC and plant protein with a high level of automation, and an increase in sample processing of ~10-fold compared with commonly-used methods, along with a 3-fold cost reduction.

CP16149Genotypic evaluation of introduced white clover (Trifolium repens L.) germplasm in New Zealand

M. Z. Z. Jahufer, J. L. Ford, D. R. W. Woodfield and B. A. Barrett
pp. 897-906

The genetic potential of white clover germplasm, from broad geographic origins, was evaluated based on their F1 crosses to three elite New Zealand cultivars. The parents and progeny were evaluated at Palmerston North under rotational grazing by sheep. Three morphological traits and seasonal dry matter yield were measured over four years. The study indicated that choice of adapted cultivar with which to cross is important, and germplasm from Australasia was a valuable source of adaptive variation.

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