This study evaluated variation in photosynthetic parameters at various growth stages in 43 wheat genotypes under optimal and low nitrogen supply. Based on all studied parameters, a dissimilarity matrix was constructed, separating the 43 genotypes into groups. Some genotypes appear to have relative tolerance to low nitrogen supply and a potential to be used in discerning the molecular basis of tolerance to low nitrogen supply.

Implementation of Alternate Furrow Irrigation (AFI) resulted in a significant saving in irrigation water and improved IWUE in corn production in a semi-arid region. Due to the severe shortage of fresh water for agricultural use in these regions, AFI has good potential for developing water-saving strategies for maize production.

Biosolids are organic fertilisers derived from treated and stabilised sewage sludge that are able to improve soil’s physical, chemical and biological properties, thus representing an alternative to the use of livestock manure for crops. Compared with mineral fertiliser, biosolids reduced N₂ fixation of field bean, but increased seed yield. Biosolids can be utilised as slow-release nitrogen sources in legume crops.

Cover crops of six different legumes and millet were compared to a chemical fallow control over a long-fallow in a subtropical farming system. Legume cover crops contributed little N benefits, were slower to accumulate biomass necessitating later termination, and had less persistent ground cover than millet. Legume cover crops induced higher risks of reduced soil water storage and resulting yield reductions in subsequent crops than millet.

Essential hedging in macadamia orchards affects fruit yield through diversion of stored resources to vegetative regrowth. Branches were pruned in autumn or spring, with factorial combinations of stem girdling, partial defoliation of the previous growth flush and progressive defoliation of the resulting vegetative flush shoot. Quantitative description of dry matter transfers from the stem and leaves of the previous growth flush, and from more distant parts of the tree and leaves of the new flush shoot, will enhance carbon allocation models for macadamia tree growth and management.

ToC Abstract: A weed survey carried out in the Glyphosate-tolerant (GT) cotton regions of Australia has indicated a shift in weed populations compared to the previous surveys in the region. Volunteer GT cotton, Echinochloa colona (L.) Link, Conyza bonariensis (L.) Cronq. and Sonchus oleraceus L. were some of the major weeds. The results of this study demand for diversified weed-management options to minimise the dominance of emerging weeds in the cotton producing regions.

Production and environmental benefits of perennial grasses such as phalaris could be extended to the mixed farming zone of southern Australia if persistence in dry marginal rainfall areas was improved. Evaluation of genetic resources in phalaris in 430-460 mm annual rainfall environments found that adaptation was related to early reproductive maturity, higher summer dormancy and high winter growth activity. Resources potentially suitable for commercialisation were identified.

Increasing our understanding of how weeds compete with crops for critical nutrients such as nitrogen (N) may lead to innovative weed-management strategies. This study shows that several plant species commonly occurring as weeds in Australian cropping systems alter the N cycle in their root-zones through biological nitrification inhibition. By retaining N as ammonium in the rhizosphere, these weeds may gain a competitive advantage over crop species that prefer nitrate.