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 66 Number 5 2015

CP14308Yield and water-use efficiency of wheat in a high-rainfall environment

Tina Botwright Acuña, Shaun Lisson, Peter Johnson and Geoff Dean
pp. 419-429

Desktop modelling studies were used to benchmark wheat WUE and to explore the sensitivity of yield, water use and WUE to changes in management practice in a high-rainfall environment. The upper limit for WUE was ~30 kg/ in excess of 180 mm evaporation, which is 16% higher than previous estimates at this southerly latitude for wheat. Attainable WUE ranged from 58% to 100% of potential WUE and was limited by nitrogen supply and water loss through evaporation, drainage and runoff.

CP14191Responses to phosphorus among wheat genotypes

Glenn McDonald, William Bovill, Julian Taylor and Robert Wheeler
pp. 430-444

Responses to phosphorus (P) were examined in c. 50 varieties of bread wheat over three years. There were large effects of site and season on the response to P, but some genotypes showed consistently low and others high response to P. Genotypic variation in grain yield was more strongly related to variation in P utilisation efficiency than to variation in P uptake among wheat genotypes, which was associated with differences in P harvest index.

The dynamic quantitative trait loci (QTL) for total starch content (TSC), amylose (AMS) and amylopectin (AMP) in wheat grain were studied at five stages under three treatments in two seasons by unconditional and conditional QTL mapping. The QTsc4A.1 and QAms4A.1 were identified continuously at five stages in different environments by unconditional mapping and they also showed the net expression from 12 DAF to 22 DAF by conditional mapping. These indicated the two loci played an important role in starch synthesis.

This paper aims at providing insights into how grain yield is defined during the pre-heading phase in 2- and 6-row barleys under contrasting N and radiation environments, using a model proposed by RA Fischer for grain number determination. Results from our study confirmed that the amount of carbon produced during the active spike growth phase and partitioned to the growing spike was the main driver explaining variations in grain number per unit area in barley.

CP14293Herbicide resistance in Bromus and Hordeum spp. in the Western Australian grain belt

Mechelle J. Owen, Neree J. Martinez and Stephen B. Powles
pp. 466-473

Random surveys conducted in Western Australia have shown that herbicide resistance is common for the major crop weed species. In 2010, a survey revealed that resistance to the ACCase and ALS-inhibiting herbicides had increased for Lolium rigidum. For the emerging crop weeds, Bromus and Hordeum, resistance was also detected to these same herbicides although at much lower levels. Around 13% of Bromus populations and 8% of Hordeum populations were resistant to the ALS-inhibiting herbicides.

Genetic modification of white clover plants for virus resistance, bloat-safety and stress tolerance is likely to have large economic benefits for livestock farmers. Since white clover pollen is a common constituent of honey, this study aimed to develop tools for detecting the presence of DNA from pollen of genetically-modified white clover plants in pollen and honey samples. Two transgenes, namely, the Alfalfa mosaic virus coat protein gene (AMV CP) and the neomycin phosphotransferase 2 (npt2) selectable marker gene, were able to be detected in pollen harvested from white clover flowers, honey bees that had been foraging white clover plants and honey using PCR-based methodologies.

Germination speed were evaluated for 137 canola (Brassica napus L.) accessions, the identified fast and slow germination accessions were validated in repeated Petri dish and pot experiments. Based on germination speed and seedling characteristics, four accessions with high early vigour and four with low early vigour were identified. The identified accessions with contrasting early vigour can be used to study the genetic and molecular mechanism of seed germination and seedling development and to breed superior canola cultivars.

A study was undertaken of the effectiveness of management options to improve grain yields on water-logging prone sodic Vertosol soil in the southern Wimmera region of Victoria. Grains yields were increased significantly (by up to 60%) if both soil physiochemical properties and Nitrogen nutrition were simultaneously improved. Largest yield increases were obtained when raised beds and composted organic matter ameliorants were applied.

Fusarium wilt is a major constraint of crop and pasture legume production worldwide. We characterised the response of barrel medic (Medicago truncatula) to the disease according to plant age, plant substrate and inoculation method and established an inoculation method suitable for the molecular characterisation of the disease–legume interaction. This will be very useful to unravel the resistance mechanisms for efficient control of the disease.

Atmospheric nitrogen deposition significantly affected the reproduction pattern of Chloris virgata. The relationship between seed size and seed number in C. virgata was allometric under different N levels and significant negative correlations between seed size and seed number were found at high and low N levels. The highest seed vigour occurred at control, while seed size was highest at low and high N levels.

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