Growers in the wheatbelt of south-eastern Australia need increases in water-limited potential yield (PY_w) in order to remain competitive in a changing climate and with declining terms of trade. In drought-prone regions, flowering time is a critical determinant of yield for wheat (Triticum aestivum L.). Flowering time is a function of the interaction between management (M, establishment date), genotype (G, development rate) and prevailing seasonal conditions. Faced with increasing farm size and declining autumn rainfall, growers are now sowing current fast-developing spring wheat cultivars too early. In order to widen the sowing window and ensure optimum flowering dates for maximum yield, new G × M strategies need to be identified and implemented. This study examined the effect of manipulating genotype (winter vs spring wheat and long vs short coleoptile) and management (sowing date, fallow length and sowing depth) interventions on yield and flowering date in high-, medium- and low-rainfall zones in south-eastern Australia. Twelve strategies were simulated at nine sites over the period 1990–2016. At all sites, the highest yielding strategies involved winter wheats with long coleoptiles established on stored subsoil moisture from the previous rotation, and achieved a mean yield increase of 1200 kg/ha or 42% relative to the baseline strategy. The results show promise for winter wheats with long coleoptiles to widen the sowing window, remove the reliance on autumn rainfall for early establishment and thus stabilise flowering and maximise yield. This study predicts that G × M strategies that stabilise flowering may increase PY_w.

Over 100 wheat varieties and breeding lines from India and Australia were screened in alkaline and waterlogged soils in 10 environments over two years at one drained location and two naturally waterlogged locations in India. Mean trial grain yield was reduced up to 70% in the environments where genotypes were waterlogged for up to 15 days at the vegetative stage in alkaline soil relative to plants in drained soils. Agronomic traits (plant height, tiller number, 1000-grain weight) of genotypes were also reduced under waterlogging. At one waterlogged site, up to 68% of the genetic diversity for predicted grain yields under waterlogging could be accounted for by number of tillers (r² = 0.41–0.68 in 2011 and 2010, respectively) and positive correlations also occurred at the second site (r² = 0.19–0.35). However, there was no correlation between grain yields across varieties under waterlogging in any trials at the two waterlogged locations. This may have occurred because waterlogged sites differed up to 4-fold in soil salinity. When salinity was accounted for, there was a good correlation across all environments (r² = 0.73). A physiological basis for the relationship between tillering and waterlogging tolerance is proposed, associated with crown root development. Results are compared with findings in Australia in acidic soils, and they highlight major opportunities for wheat improvement by selection for numbers of tillers when crops are waterlogged during vegetative growth.

Genetic improvement in phosphorus (P) use efficiency (i.e. the ratio of biomass or yield at nil P to that at a given rate of application) is an important goal to improve P recovery and P efficiency of farming systems. Experiments were conducted at three sites in South Australia between 2009 and 2011 to characterise genetic variation in yield with no applied P and in the response to P fertiliser among a diverse range of barley (Hordeum vulgare L.) genotypes. In each experiment, 39–54 genotypes were grown at 0 or 30 kg P/ha. Responses to P were measured near the beginning of stem elongation by using normalised difference vegetation index (NDVI) and by harvesting the grain. Rhizosheath size was also measured on seedlings. Consistent differences in growth and yield at 0 kg P/ha were measured among the genotypes. By contrast, there were large environmental effects on responses to P, but some genotypes showed consistent responses. Measurements of growth, yield and P uptake on a subset of genotypes showed that most of the variation in biomass and yield could be attributed to variation in P-uptake efficiency (net total P uptake per unit available P) rather than to P-utilisation efficiency (biomass or yield per unit total P uptake). The size of the rhizosheath made a small contribution to variation in NDVI but not grain yield, suggesting that rhizosheath size may be of some benefit to early growth but that this does not persist through to yield. Genetic correlations between NDVI and yield were often weak but were generally positive at 0 kg P/ha. Correlations between responses in NDVI and responses in grain yield were low and often negative. The study identified several barley genotypes that showed consistent differences in yield at low P and responses to P; however, selection for P efficiency based solely on responses in vegetative growth may not be appropriate. Variation in P uptake appeared to be more important than P-utilisation efficiency for P efficiency in barley.

The important plant growth regulator 5-aminolevulinic acid (ALA) could promote low-temperature stress tolerance of many plants; however, the underlying mechanisms remain to be elucidated. We investigated the effects of exogenously applied ALA on seedling morphology, antioxidant enzyme activity and photosynthetic capacity of maize (Zea mays L.) seedlings under low-temperature stress. Two cultivars, low-temperature-sensitive cv. Suiyu 13 (SY13) and low-temperature-tolerant cv. Zhengdan 958 (ZD958), were subjected to four treatments: low-temperature without ALA treatment, low-temperature after ALA treatment, normal temperature without ALA treatment, and normal temperature after ALA treatment. Plant morphological growth, proline content, antioxidant enzyme activity and photosynthetic capacity were determined. ALA treatment significantly decreased the inhibitory effects of low-temperature stress on seedling dry weight and increased proline accumulation under low temperatures in ZD958. Pre-application of ALA significantly improved superoxide dismutase and catalase activities in SY13 under low-temperature stress. Furthermore, treating maize seedlings with ALA resulted in significant enhancement of ribulose-1,5-bisphosphate (RuBP) carboxylase activity under low-temperature stress in both cultivars. Pre-treatment with ALA relieved the damage caused by low-temperature stress to maize seedlings, particularly in the low-temperature-sensitive cultivar. Therefore, ALA at appropriate concentrations may be used to prevent reductions in maize crop yield due to low-temperature stress.

Piriformospora indica is one of the cultivable root-colonising endophytic fungi of the order Sebacinales, which efficiently promote plant growth, uptake of nutrients, and resistance to biotic and abiotic stresses. The aim of this study was to evaluate the effect of P. indica on millet (Panicum miliaceum L.) under water-stress conditions. Two field experiments were carried out in a factorial arrangement at Bu-Ali Sina University of Hamedan, Iran, during 2014 and 2015. The first factor was three levels of water-deficit stress, with irrigation after 60 mm (well-watered), 90 mm (mild stress) and 120 mm (severe stress) evaporation from pan class A. The second factor was two levels of fungus P. indica: inoculated and uninoculated. Results showed that water-deficit stress significantly decreased grain yield and yield components. Colonisation by P. indica significantly increased number of panicles per plant, number of grains per panicle and 1000-grain weight, regardless of water supply. Inoculation with P. indica increased grain yield by 11.4% (year 1) and 19.72% (year 2) in well-watered conditions and by 35.34% (year 1) and 32.59% (year 2) under drought stress, compared with uninoculated plants. Maximum flag-leaf area (21.71 cm²) was achieved with well-watered conditions. Severe water stress decreased flag-leaf area by 53.36%. Flag-leaf area was increased by 18.64% by fungus inoculation compared with the uninoculated control. Under drought conditions, inoculation with P. indica increased plant height by 27.07% and panicle length by 9.61%. Severe water stress caused a significant decrease in grain phosphorus concentration, by 42.42%, compared with the well-watered treatment. By contrast, grain nitrogen and protein contents were increased about 30.23% and 30.18%, respectively, with severe water stress. Inoculation with P. indica increased grain phosphorus by 24.22%, nitrogen by 7.47% and protein content by 7.54% compared with control. Water stress reduced leaf chlorophyll and carotenoid concentrations, whereas P. indica inoculation enhanced chlorophyll concentrations by 27.18% under severe water stress. The results indicated the positive effect of P. indica on yield and physiological traits of millet in both well-watered and water-stressed conditions.

Three experiments were conducted to develop a bioassay method for assessing the bioavailability of prosulfocarb, pyroxasulfone and trifluralin in both crop residue and soil. In preliminary experiments, Italian ryegrass (Lolium multiflorum Lam.), cucumber (Cucumis sativus L.) and beetroot (Beta vulgaris L.) were tested as bioassay plant species for the three pre-emergent herbicides. Four growth parameters (shoot length, root length, fresh weight and dry weight) were measured for all plant species. Shoot-length inhibition was identified as the most responsive to the herbicide application rates. Italian ryegrass was the most sensitive species to all tested herbicides, whereas beetroot and cucumber had lower and similar sensitivity to shoot inhibition for the three herbicides. The bioassay species performed similarly in wheat and canola residues collected a few days after harvest. In bioassay calibration experiments, dose–response curves were developed for prosulfocarb, pyroxasulfone and trifluralin in a sandy loam soil typical of the grain belt of Western Australia and with wheat residue. The developed bioassay uses ryegrass shoot inhibition for relatively low suspected concentrations of herbicide, and cucumber shoot inhibition for higher rates. The bioassay was validated by spraying the three herbicides separately onto wheat residue and soil and comparing the concentrations derived from chemical analysis with those from the bioassay. All of the linear correlations between concentrations derived from chemical analyses and the bioassays were highly significant. These results indicate that the bioassay calibration curves are suitable for estimating herbicide concentrations in crop residue collected soon after harvest and a sandy-loam soil, low in organic matter.

A field experiment was conducted in a free-air CO₂ enrichment (FACE) facility to investigate the effect of elevated atmospheric CO₂ on growth and physiology of green gram (Vigna radiata (L.) R.Wilczek) and associated weed species (Euphorbia geniculata Ortega and Commelina diffusa Burm.f.). Physiological and reproductive behaviour and interaction of the crop and two weed species under elevated CO₂ was also studied. Plants were grown under ambient (390 ± 5 ppmv) and elevated (550 ± 50 ppmv) CO₂. The results showed that growth, photosynthesis and carbonic anhydrase activity increased in all the test species. Stomatal conductance and transpiration decreased in V. radiata (5.1% and 30.5%, respectively) and C. diffusa (19% and 13.7%) but increased in E. geniculata (6.5% and 27.6%), suggesting a unique adaptive potential of E. geniculata at elevated CO₂. Higher accumulation of reactive oxygen species (hydrogen peroxide and superoxide) was noticed at elevated CO₂ in V. radiata than in E. geniculata and C. diffusa. Potential of E. geniculata to maintain redox homeostasis in its original state may provide an advantage over two other species in adaptation to climate change. Isoenzyme patterns of superoxide dismutase and stronger activity of antioxidant enzymes suggest species-specific differential regulation and induction of new isoforms under elevated CO₂. Enrichment of atmospheric CO₂ at a competitive density of weeds lowered the yield (12.12%) and quality of green gram seed, with diminished protein content (16.14% at ambient CO₂ to 15.42% at elevated CO₂) and enhanced carbohydrate content (3.11%). From the study, it may be concluded that a rise in atmospheric CO₂ concentration affects plant performance in a species-specific manner. Among the three species, E. geniculata emerged as most responsive to elevated CO₂, showing higher transpiration and stomatal conductance and a stronger antioxidant defence system in a higher CO₂ atmosphere. At elevated CO₂, weed–crop interaction altered in favour of weeds leading to considerable yield loss of green gram seed.

Physiological indices of two lines of hyacinth bean (Lablab purpureus (L.) Sweet), MEIDOU 2012 and NANHUI 23, were compared during a progressive course of water-withholding treatments. MEIDOU 2012 was shown to be a superior drought-tolerant genotype. A suppressive subtractive hybridisation library was then constructed by using drought-stressed MEIDOU 2012 roots and sequenced to screen for transcripts with differential abundance variations. In total, 2792 unigenes were assembled from 4064 drought-induced expressed sequence tags. Comparative analysis with other legume genomic sequences, including soybean (Glycine max (L.) Merr.), common bean (Phaseolus vulgaris L.) and lucerne (Medicago sativa L.), was performed, from which 338 unigenes associated with root growth and drought response were identified. Among these unigenes, 27 transcription factors were deduced by functional-domain prediction. The transcription levels of a GRAS and a WRKY transcription factor were confirmed to be responding sensitively to water stresses. Additionally, protein–protein interaction (PPI) networks were predicted for all drought-induced root-related unigenes with different stringency levels. A mitogen-activated protein kinase (MAPK4) and an EF-hand calcium-binding protein (CML24) module were pinpointed to be putative ‘master’ signalling hubs in these PPI networks. Detailed examination of these genomic resources would further reveal key regulators of Lablab drought tolerance.

Annual ryegrass (Lolium rigidum Gaud.) is a troublesome invasive plant in southern Australian cropping systems and is typically infected with a fungal endophyte, Epichloë occultans. Potential links between herbicide resistance and endophyte infection were investigated in this study. We surveyed 391 ryegrass populations from geographically distinct, naturalised pasture and cropping areas across southern Australia and compared frequencies of seed-borne endophyte infection in the collected seed samples from mature annual ryegrass. Data on herbicide resistance from similar seedlots were cross-referenced with endophyte infection frequency to examine the potential relationship between herbicide resistance and endophyte infection. Seeds from cropping paddocks exhibited a significantly higher frequency of endophyte infection than pasture paddocks sampled from the same region. Frequencies of endophyte infection in annual ryegrass declined across Australia during 2001–09, whereas the opposite trend was observed during 2009–12. Impacts of the Australian Millennium Drought, the correspondingly altered rainfall patterns and environmental selection pressures have a role in determining observed endophyte infection frequencies. However, there was no significant correlation between endophyte frequency and herbicide resistance in the populations evaluated. Differences in endophyte infection frequencies were associated with farming practices, and require further examination to determine causative selection pressures encountered in Australian field settings.