This paper reviews current knowledge concerning the occurrence, losses caused, epidemiology, and management of virus diseases of annual pasture legumes. The viruses commonly present are spread by contact, or aphid vectors either non-persistently or persistently. Whether they are seed-borne and their means of transmission are critical factors determining their incidences within pastures in climatic zones with dry summers or substantial summer rainfall. Large-scale national or state surveys of subterranean clover pastures revealed that some viruses reach high infection incidences. Contamination with seed-borne viruses was widespread in plots belonging to annual pasture legume improvement programs and seed stocks of subterranean clover, annual medics, and alternative annual pasture legumes, and in commercial annual medic seed stocks. Yield loss studies with grazed swards were completed for three common viruses: two in subterranean clover and one in annual medics. These studies demonstrated considerable virus-induced losses in herbage and seed yields, and established that virus infection causes deteriorated pastures with high weed contents even when foliar symptoms are mild. Comprehensive integrated disease management tactics involving phytosanitary, cultural, chemical, or host resistance measures were devised for these three viruses in infected pastures, and for seed-borne viruses in annual pasture legume improvement programs. Several other viruses are potentially important, but, with these, quantification of losses caused in grazed swards is lacking and information on incidences in pastures is currently insufficient. Critical research and development gaps that need addressing are identified.

Chickpea (Cicer arietinum L.) is an important food legume and heat stress affects chickpea ontogeny over a range of environments. Generally, chickpea adapts to high temperatures through an escape mechanism. However, heat stress during reproductive development can cause significant yield loss. The most important effects on the reproductive phase that affect pod set, seed set and yield are: (1) flowering time, (2) asynchrony of male and female floral organ development, and (3) impairment of male and female floral organs. While this review emphasises the importance of high temperatures >30°C, the temperature range of 32–35°C during flowering also produces distinct effects on grain yield. Recent field screening at ICRISAT have identified several heat-tolerant germplasm, which can be used in breeding programs for improving heat tolerance in chickpea. Research on the impact of heat stress in chickpea is not extensive. This review describes the status of chickpea production, the effects of high temperature on chickpea, and the opportunities for genetic improvement of chickpea tolerance to high temperatures.

Dual-purpose canola (Brassica napus) describes the use of a canola crop for grazed winter forage before seed production, a practice that has only recently been developed in southern Australia. Long-season winter canola has been grazed without yield penalty in higher rainfall zones of Australia (>650 mm) and the USA, but the potential areas are small. The feasibility to graze spring canola varieties across wider areas of the medium-rainfall (450–650 mm), mixed-farming zone in Australia is therefore of interest. We conducted a series of six field experiments involving a range of canola cultivars and grazing management and agronomy systems from 2007 to 2009 at Young in southern New South Wales, Australia, to determine the feasibility of and refine the principles for grazing dual-purpose spring canola without significant yield penalty. Mid-season, Australian spring canola cultivars including conventional and hybrid varieties representing a range of herbicide tolerance (triazine-tolerant, Clearfield^®, and Roundup Ready^®) were sown from 16 April to 12 May and grazed with sheep at a range of growth stages from early vegetative (June) to mid-flowering (September). In general, early-sown crops (sown mid-April) provided significant grazing (∼800 dry sheep equivalent grazing days/ha) in winter before bud elongation, and recovered with no impact on grain yield or oil content. As previously reported, yield was significantly reduced (by up to 1 t/ha) when grazing occurred after buds had elongated (late July), due to the delayed flowering associated with bud removal by sheep and insufficient time for biomass and yield recovery. However, yield was also reduced in crops grazed before bud elongation if insufficient residual biomass remained (<1.0 t/ha for late July lock-up) to facilitate crop recovery even when there was little delay in crop development. We suggest that refinements to the existing ‘phenology-based’ grazing recommendations would assist to avoid yield loss in grazed spring varieties, and propose three grazing stages (safe, sensitive, and unsafe) that integrate the impacts of time, crop growth stage, residual biomass, and seasonal conditions to avoid yield loss under different circumstances. Such refinements to reduce the likelihood of grazing-induced yield loss would provide more confidence for mixed farmers to maximise the benefits from dual-purpose canola in different environments. Based on the outcomes of these experiments, dual-purpose spring canola is likely to have significant potential for wider application in other mixed farming zones, with similar region-specific refinements based on the principles reported here.

A key goal in the breeding for aphid resistance of cultivated lupins is to manipulate the levels and distributions of alkaloids. Lupin alkaloids are known to be responsible for resistance to herbivorous insects, but the total seed alkaloid level must remain under 0.02% for animal and human consumption. Yellow lupin (Lupinus luteus L.) is being investigated as a new legume crop for Western Australia (WA), but most lines produced to date have been very susceptible to aphids. In contrast, breeders in WA have had ongoing success releasing narrow-leafed lupin (L. angustifolius L.) cultivars with adequate resistance to aphids. In this study, aphid performance was evaluated on yellow lupin plants in the glasshouse from an F₂ population derived from a cross between Teo, a yellow lupin cultivar resistant to aphids and with high total alkaloid levels, and Wodjil, a single plant selection from Teo that is susceptible to aphids and has low total alkaloid levels, and their parents. Resistance in Teo and the F₂ progeny was strongly associated with the alkaloids gramine and a gramine analogue. The absence of plants with intermediate levels of these alkaloids in progeny of this cross makes it unlikely that aphid-resistant lines can be generated using Teo as the resistance source. On the other hand, different alkaloids were correlated with aphid resistance in the narrow-leafed lupin cultivar Kalya, and aphid resistance was more evenly distributed among progeny of a cross of the resistant cultivar Kalya with the susceptible cultivar Tallerack. For this reason, additional yellow lupin lines with a more diverse alkaloid profile were selected for further study from the Australian lupin breeding program. A wide variation in the aphid tolerance among lines was observed and aphid tolerance was positively correlated with alkaloid content. However, four lines were identified with moderate levels of aphid resistance in a low alkaloid background. These lines had varying alkaloid profiles, but as expected none were dominated by gramine and its analogues. We believe these lines offer a greater opportunity for aphid resistance breeding in yellow lupins.

Narrow-leafed lupin (Lupinus angustifolius L.) is an important grain legume crop in Australia. Metribuzin is an important herbicide used to control weeds in lupin crops. This study investigated metribuzin tolerance mechanism in narrow-leafed lupin by comparing two induced mutants (Tanjil-AZ-33 and Tanjil-AZ-55) of higher metribuzin tolerance with the susceptible wild type. Sequencing of the highly conserved region of the chloroplast psbA gene (target site) revealed that the sequences of the wild type and the mutants were identical and therefore metribuzin tolerance is not target site based. Photosynthetic activity was measured and the leaf photosynthesis of the two tolerant mutants was initially inhibited after metribuzin treatment, but recovered within 2.5 days whereas that of the susceptible plants remained inhibited. The photosynthetic measurements confirmed the target site chloroplast was susceptible and the tolerance mechanism is non-target site based. Investigation with known cytochrome P450 monooxygenase inhibitors (omethoate, malathion and phorate) showed that tolerance could be reversed in both mutants, indicating the tolerance mechanism in two tolerant mutants may involve cytochrome P450 enzymes. Interestingly, the inhibitor tridiphane reversed metribuzin tolerance of only one of the two tolerant mutants, indicating diversity in metribuzin tolerance mechanisms in narrow-leafed lupin. These results signify that further investigation of metribuzin metabolism in these plants is warranted. In conclusion, metribuzin tolerance mechanism in lupin mutants is non-target site based, likely involving P450-mediated metribuzin metabolism.

Sugarcane improvement has traditionally been conducted by nationally focussed breeding programs, with some exchange of elite cultivars among some programs. It has been generally assumed by breeders that genotype × country interactions are large, and therefore selection trial data in one country may be of limited relevance to another. However, no studies quantifying clone × country interactions have been reported to our knowledge. In research reported here, a common set of mostly unselected sugarcane genotypes was evaluated in commercial production environments in Australia and China. Consistent with past studies, genotype × site interaction was an important source of variation within each country. Overall a moderate to high genetic correlation existed between production environments in China and Australia for cane yield and sugar content (0.77 for both traits). This suggests that despite difference in environmental conditions and crop management in production environments between countries, that selection trials in China have some relevance for selecting clones for Australian environments and vice versa. It also supports the hypothesis that regular exchange of selected germplasm from effective breeding programs between countries will have mutual benefits.

The population size and symbiotic performance (ability to fix N₂) of rhizobia (Rhizobium leguminosarum bv. viciae) capable of nodulating field pea (Pisum sativum) were assessed in 114 soils from Mediterranean-type environments of southern Australia. All soils were collected in autumn, before the growing season, and had a history of crop legumes including field pea, faba bean, lentil, or vetch. The most probable number (MPN) technique, with vetch as a trap plant, was used to estimate the numbers of pea rhizobia in soils. Of the soils tested, 29% had low numbers of pea rhizobia (<100 rhizobia/g), 38% had moderate numbers (100–1000/g), and the remaining 33% had >1000/g. Soil pH, the frequency of a host crop in the rotation, and the number of summer days with a maximum temperature >35°C were strongly correlated with the pea rhizobia population size.

Symbiotic performance (SP) of pea rhizobia in soils was assessed for soils with a MPN >100 rhizobia/g. An extract of the soils was used to inoculate two field pea cultivars growing in a nitrogen-deficient potting media in the greenhouse. Plants were grown for 5 weeks after inoculation and shoot dry matter was expressed as a percentage of the dry matter of plants grown with a commercial strain R. leguminosarum bv. viciae, SU303. Symbiotic performance ranged from 25 to 125%. One-quarter of the soils assessed had suboptimal SP (i.e. <70%). Soil and climatic variables were weakly associated with SP, with pH and average annual rainfall accounting for 17% of the variance.

This research highlights the complexity of factors influencing population size and symbiotic performance of pea rhizobia in soils. Options for the improved management of populations of pea rhizobia in Mediterranean environments are discussed. Specifically, our data indicate that inoculation of pea crops is likely to be beneficial where pH(H₂O) <6.6, particularly when summers have been hot and dry and when a host has been absent for ≥5 years, as numbers of rhizobia are likely to be below the thresholds needed to optimise nodulation and crop growth. New inoculation technologies and plant breeding will be required to overcome large populations of pea rhizobia with suboptimal SP.

Canola is a major oil crop in the Yangtze River Basin of China, and its yield and oil content vary significantly from year to year due to changes in sowing time and inter-annual climate variability. However, there have been no studies to quantify the impacts of sowing time and climate variability. Experimental data to analyse the response of canola growth to sowing date are limited to a few seasons; however, combining these data with modelling provides an efficient means to study the impact of sowing date and historical climate variation. The APSIM-Canola model was calibrated and tested using data from three field experimental sites in the Yangtze River Basin. These experiments included different cultivars and sowing dates, and recorded major phenological stages, biomass, and grain yield. After calibration of the phenological parameters and maximum harvest index, the model was able to simulate the onset of phenological stages with different sowing dates, and to explain 75% of the variation in biomass and yield caused by late sowings. However, the model overestimated canola yield under late sowing dates. The results revealed that canola yield declined linearly with late sowing time, mainly due to shortened vegetative growth stages, and varied significantly due to inter-annual climate variability. The yield potential at the study region is ∼3 t/ha, on average. However, this potential cannot be achieved in the rice–canola double-cropping system due to later sowing time after rice harvest in mid–later October. Transplanting canola may still be an effective measure against the constraint of season length to achieving higher yields of both rice and canola.

In order to determine the importance of awn photosynthesis on grain yield under terminal drought, six two-rowed cultivars of barley representing high yielding commercial releases from 1961 to 2006 were studied in a glasshouse experiment at CSIRO, Western Australia. The cultivars were grown with and without watering from anthesis. Detailed measurements of plant water status, awn, flag and penultimate leaf photosynthetic rate were made from anthesis. At final harvest, biomass, yield and yield components were measured. Awn net photosynthesis rate (Pn) was lower than penultimate and flag leaf and decreased gradually after anthesis. The rate of decreasing Pn was rapid under terminal drought. There was no difference in awn Pn among cultivars under well-watered conditions, but under terminal drought the awn Pn of barley cultivars Baudin and Clipper decreased faster than Vlaming, Gairdner and Stirling. Surface area of awns in each cultivar was higher than the flag and penultimate leaf. Thus, total awn photosynthesis under both well-watered and terminal drought conditions was higher than flag leaf photosynthesis. In Vlaming, total awn photosynthesis was higher than penultimate leaf photosynthesis. Grain yield of the cultivars Baudin, Covette and Gairdner was affected by terminal drought, but grain yield did not correlate with awn total photosynthesis. Under well-watered conditions awn Pn had a significant negative correlation with ear weight. We suggest that under terminal drought, higher awn area does not lead to higher grain yield because sink size may be the factor limiting grain yield in barley.