Sustainable Grains Production Course - building grains industry futures

The Sustainable Grains Production course was established in 2003 by the University of New England (UNE) with funding from Grains Research and Development Corporation (GRDC). The aim of the course was to improve the knowledge and skills base of people, particularly advisors, working in the northern grains region of Australia, and to increase the economic and environmental performance of the grains industry. Through a survey of past and current students, UNE and GRDC sought to review the impact of the Sustainable Grains Production course on graduates, and within the grains industry. The survey was conducted in October, 2011, with 70 responses being received from 150 valid email addresses. Fifty percent of respondents were agronomists, and an additional 20% were from farms, with most from NW NSW and SE Queensland. Grains (GRNS) study was valued for its specificity in grains production, and the opportunity it gave students to develop their knowledge and skills in grain production in areas which were directly relevant to their careers. As a result of their study, 75% of respondents had spoken to farmers about a broader range of issues, and 66% had made or suggested changes to farming systems, showing that the course is achieving its intended outcomes of increasing grains industry human capacity, and accelerating the adoption of research findings. Additionally, all respondents thought that the grains industry benefitted from the course, and 57% of students thought that GRNS study had helped them obtain a promotion or new job

Phosphorus-use efficiency, growth and yield of spelt wheat ('Triticum aestivum ssp. spelta') compared with standard wheat ('T. aestivum ssp. vulgare') in south-eastern Australia

Experiments were conducted in the glasshouse and the field to assess the phosphorus-use efficiency, yield, and yield components of several spelt wheat genotypes in comparison with standard bread wheats. Spelt genotypes had much lower grain yield than standard bread wheats, in both a wellwatered glasshouse and three field situations. The reduction in yield was often as great as 60% and was largest in late-flowering spelt genotypes. Spelt genotypes responded to increasing amounts of applied phosphorus (P) fertiliser, adequately acquired P from soil, and some had higher total amounts in their tissues; however, these P reserves were not as efficiently converted into grain yield as standard bread wheat cultivars, primarily due to the growth of tall, unproductive tillers, and lower kernel number and kernel size. There was no evidence of spelt yielding better than common wheat under conditions of P-deficiency. There is great potential to breed improved spelt genotypes through relatively simple modification of yield components and phenology, but whether this can be achieved while maintaining the grain quality attributes valued highly by the organic industry remains to be seen. Breeding for improved spelt should target reduced height and tiller number, early flowering, and larger kernels

Extractable phosphorus (Colwell) concentrations of soil after banding fertiliser with seed in relation to the critical phosphorus requirement of a wheat crop

The phosphorus (P)-balance efficiency of wheat crops in southern Australia is typically about 50% (i.e. about 2 units of P are applied in fertiliser to produce 1 unit of P in grain). We investigated the concentrations of Colwell extractable P in the surface soil (0-10 cm) of a red kandosol (pHCaCl2 4.42) within the planting row of a wheat crop sown on 31 May 2011 at Condobolin, NSW. Triple superphosphate had been banded at 0, 4, 8 or 20 kg P/ha with the wheat seed which was sown at 4.5 cm depth. The aim was to quantify the temporal mismatch between P availability in the band and the critical P requirement (Colwell P concentration corresponding to 95% of maximum growth rate) of the crop. The critical Colwell P concentration of topsoil in the crop row was initially low, but increased during tillering and was ~54 mg P/kg during grain filling. To achieve this concentration of Colwell P after anthesis it was necessary to apply ~15.3 kg P/ha at sowing. It was estimated that this would initially generate a Colwell P concentration of 80-90 mg P/kg and it was concluded that the Colwell P concentration of topsoil in the crop row (i.e. soil associated with the fertiliser band) would remain above the critical requirement of the crop for the first 126 days (~70%) of the crop's growth period

Re-evaluating sowing time of spring canola ('Brassica napus' L.) in south-eastern Australia - how early is too early?

Optimising the sowing date of canola ('Brassica napus' L.) in specific environments is an important determinant of yield worldwide. In eastern Australia, late April to early May has traditionally been considered the optimum sowing window for spring canola, with significant reduction in yield and oil in later sown crops. Recent and projected changes in climate, new vigorous hybrids, and improved fallow management and seeding equipment have stimulated a re-evaluation of early-April sowing to capture physiological advantages of greater biomass production and earlier flowering under contemporary conditions. Early-mid-April sowing generated the highest or equal highest yield and oil content in eight of nine field experiments conducted from 2002 to 2012 in south-eastern Australia. Declines in seed yield (-6.0% to -6.5%), oil content (-0.5% to -1.5%) and water-use efficiency (-3.8% to -5.5%) per week delay in sowing after early April reflected levels reported in previous studies with sowings from late April. Interactions with cultivar phenology were evident at some sites depending on seasonal conditions. There was no consistent difference in performance between hybrid and non-hybrid cultivars at the earliest sowing dates. Despite low temperatures thought to damage early pods at some sites

Sheep grazing on crop residues do not reduce crop yields in no-till, controlled traffic farming systems in an equi-seasonal rainfall environment

In southern Australia, the majority of farms combine a sheep enterprise with a cropping enterprise to form a mixed farming business. Crops are grown in sequence with pastures, and sheep graze vegetative juvenile crops and crop stubble residues after harvest. Recently, growers practicing no-till, controlled traffic cropping became concerned that grazing livestock would damage soil and reduce soil water capture, crop yield and profitability. Sheep grazing on stubbles remove residue cover and compact surface soil, but there is little published research on potential impacts on subsequent crop performance. Two experiments were conducted in high (Temora) and low (Condobolin) rainfall environments from 2009 to 2013 to determine whether sheep grazing crops during the vegetative phase and/or stubbles after harvest damaged soil, reduced soil water capture and storage or affected the performance of subsequent crops. Sheep grazing on stubbles did not reduce crop yields provided summer weeds were controlled with herbicides and at least 70% stubble cover (2–3 t/ha cereal stubble) was maintained on the soil surface. Sheep grazing on stubble increased soil strength and bulk density and reduced water infiltration rates, but rarely to levels that were detrimental to soil water capture, crop growth or grain yield. Where reduced infiltration rates did reduce soil water capture, it was due to removal of cover by grazing rather than compaction. Grazing of vegetative crops in winter when soils were generally wet further increased soil strength compared to grazing stubbles alone, but not to an extent that was detrimental to plant growth. Yield effects from grazing crops in winter were not due to soil physical effects, but to differences in plant growth in response to defoliation. Grazing of both stubbles and crops increased the availability of soil mineral N to subsequent crops which increased grain yield and protein in some seasons. The results from these experiments provide strong evidence that livestock can be retained within modern conservation cropping systems without compromising crop performance, and continue to provide the production and business risk benefits for which they have been historically valued

Plot size matters: interference from intergenotypic competition in plant phenotyping studies

Genetic and physiological studies often comprise genotypes diverse in vigour, size and flowering time. This can make the phenotyping of complex traits challenging, particularly those associated with canopy development, biomass and yield, as the environment of one genotype can be influenced by a neighbouring genotype. Limited seed and space may encourage field assessment in single, spaced rows or in small, unbordered plots, whereas the convenience of a controlled environment or greenhouse makes pot studies tempting. However, the relevance of such growing conditions to commercial field-grown crops is unclear and often doubtful. Competition for water, light and nutrients necessary for canopy growth will be variable where immediate neighbours are genetically different, particularly under stress conditions, where competition for resources and influence on productivity is greatest. Small hills and rod-rows maximise the potential for intergenotypic competition that is not relevant to a crop’s performance in monocultures. Response to resource availability will typically vary among diverse genotypes to alter genotype ranking and reduce heritability for all growth-related traits, with the possible exception of harvest index. Validation of pot experiments to performance in canopies in the field is essential, whereas the planting of multirow plots and the simple exclusion of plot borders at harvest will increase experimental precision and confidence in genotype performance in target environments

Plot size matters: interference from intergenotypic competition in plant phenotyping studies

Genetic and physiological studies often comprise genotypes diverse in vigour, size and flowering time. This can make the phenotyping of complex traits challenging, particularly those associated with canopy development, biomass and yield, as the environment of one genotype can be influenced by a neighbouring genotype. Limited seed and space may encourage field assessment in single, spaced rows or in small, unbordered plots, whereas the convenience of a controlled environment or greenhouse makes pot studies tempting. However, the relevance of such growing conditions to commercial field-grown crops is unclear and often doubtful. Competition for water, light and nutrients necessary for canopy growth will be variable where immediate neighbours are genetically different, particularly under stress conditions, where competition for resources and influence on productivity is greatest. Small hills and rod-rows maximise the potential for intergenotypic competition that is not relevant to a crop’s performance in monocultures. Response to resource availability will typically vary among diverse genotypes to alter genotype ranking and reduce heritability for all growth-related traits, with the possible exception of harvest index. Validation of pot experiments to performance in canopies in the field is essential, whereas the planting of multirow plots and the simple exclusion of plot borders at harvest will increase experimental precision and confidence in genotype performance in target environments

Plot size matters: interference from intergenotypic competition in plant phenotyping studies

Genetic and physiological studies often comprise genotypes diverse in vigour, size and flowering time. This can make the phenotyping of complex traits challenging, particularly those associated with canopy development, biomass and yield, as the environment of one genotype can be influenced by a neighbouring genotype. Limited seed and space may encourage field assessment in single, spaced rows or in small, unbordered plots, whereas the convenience of a controlled environment or greenhouse makes pot studies tempting. However, the relevance of such growing conditions to commercial field-grown crops is unclear and often doubtful. Competition for water, light and nutrients necessary for canopy growth will be variable where immediate neighbours are genetically different, particularly under stress conditions, where competition for resources and influence on productivity is greatest. Small hills and rod-rows maximise the potential for intergenotypic competition that is not relevant to a crop’s performance in monocultures. Response to resource availability will typically vary among diverse genotypes to alter genotype ranking and reduce heritability for all growth-related traits, with the possible exception of harvest index. Validation of pot experiments to performance in canopies in the field is essential, whereas the planting of multirow plots and the simple exclusion of plot borders at harvest will increase experimental precision and confidence in genotype performance in target environments

Can citrate efflux from roots improve phosphorus uptake by plants? Testing the hypothesis with near-isogenic lines of wheat

Phosphorus (P) deficiency in some plant species triggers the release of organic anions such as citrate and malate from roots. These anions are widely suggested to enhance the availability of phosphate for plant uptake by mobilizing sparingly-soluble forms in the soil. Carazinho is an old wheat ('Triticum aestivum') cultivar from Brazil, which secretes citrate constitutively from its root apices, and here we show that it also produces relatively more biomass on soils with low P availability than two recent Australian cultivars that lack citrate efflux. To test whether citrate efflux explains this phenotype, we generated two sets of near-isogenic lines that differ in citrate efflux and compared their biomass production in different soil types and with different P treatments in glasshouse experiments and field trials. Citrate efflux improved relative biomass production in two of six glasshouse trials but only at the lowest P treatments where growth was most severely limited by P availability. Furthermore, citrate efflux provided no consistent advantage for biomass production or yield in multiple field trials. Theoretical modeling indicates that the effectiveness of citrate efflux in mobilizing soil P is greater as the volume of soil into which it diffuses increases. As efflux from these wheat plants is restricted to the root apices, the potential for citrate to mobilize sufficient P to increase shoot biomass may be limited. We conclude that Carazinho has other attributes that contribute to its comparatively good performance in low-P soils