A 3-year study was conducted to measure the effect of sowing time and seeding rate on the development and yield of wheat (Triticum aestivum L.) grown under high-yielding conditions in north-eastern Victoria. A range of wheat cultivars with different development responses, including 'winter' types, was used in 2 experiments in each season. High grain yields for dryland wheat were measured in the first 2 seasons (1985-86), and in 1985, near-optimal water use efficiencies (>18 kg/ha. mm effective rainfall) were obtained. In the third season (1987) grain yield was limited by adverse climatic conditions-in the me- and post-anthesis period. In each season, grain yield declined with delay in sowing time. In 1985 there was a loss of 200-250 kg grain/ha for each week's delay in sowing time. In 1987, yield loss with delayed sowing was 50-110 kg grain/ha. In each season, cultivars with late or midseason maturity development gave the highest mean yields, and the use of these maturity types allowed earlier sowing, in mid April. However, with late sowing of wheat there was a trend for early maturity types to give higher yields, and so the use of 2 wheat cultivars with distinct maturity development responses to climate is recommended. If only 1 wheat cultivar is to be used, then a late maturity type is recommended. Higher wheat yields were also obtained as spike density increased, as a result of higher seeding rates. Our data suggest that in the higher rainfall region of north-eastern Victoria, a spike density of about 500 spikes/m2 is required to optimise wheat yields.

Three experiments, begun in successive years, were conducted between 1974 and 1979 in north-eastern Victoria to investigate the effects of rotating wheat (cv. Olympic) and 'sweet' lupins (Lupinus angustifolius cv. Uniharvest) on crop yields, soil fertility and crop diseases. The grain yield of continuous wheat was 2.58 t/ha and of continuous lupins 0.66 t/ha (P<0.05). Wheat, grown after a lupin crop, yielded 750 kg/ha more than wheat after wheat, and a second wheat crop, after lupins, yielded 420 kg/ha more than a third successive wheat crop. Lupins, grown after wheat, yielded 50-165% more than lupins after lupins. Grain nitrogen of wheat was significantly increased after lupins (P<0.01). Differences in soil mineral nitrogen were apparent ten weeks after sowing, with mean nitrogen levels of 37 and 55 kg/ha under wheat and lupins, respectively. Soil mineral nitrogen (0-20 cm) was consistently greater after lupins than after wheat (P<0.01) when measured just before seeding the succeeding crop. Overall, mean accretion of mineral nitrogen under lupins was 4 1 kg/ha.year. Residual nitrogen from lupins, after one succeeding wheat crop had been grown, was also evident (mean 23 kg/ha). Crop rotation influenced the incidence of crop diseases in wheat and lupins. Lupins after lupins suffered severely from brown leaf spot (Pleiochaeta setosa), up to 63% of plants being infected compared with only 18% after wheat. Disease incidence (mainly Gaeumannomyces graminis) in wheat increased from less than 1% in the first year of cropping, to 36% infection in year 3. When wheat was grown after lupins, disease incidence was negligible.

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Wheat grain yields, dry matter production and yield components were measured in a field experiment in north-eastern Victoria over 5 seasons where lime application and deep ripping had been carried out. The soil at the site was strongly acid (pHw 5.2 at 0-1 0 cm) and had a dense hardpan at 7.5- 17.5 cm depth. Grain yields (control yields 1981-85: 1.34, 0.25, 1.64, 2.36, 2.09 t ha-1) were increased each year by both lime (31-103% range) and deep ripping (11- 41% range), but the application of some lime was necessary to obtain benefit from deep ripping. The increased grain yield was mainly due to more heads per metre of row, although head size and grain weight were also increased by lime treatment. Lime increased the dry matter yield of roots and decreased the top to root dry matter ratio. Deep ripping increased the dry matter yield of roots at depth and also reduced root distortion where the hardpan had been shattered. In a drought season, deep ripping increased grain weight. Root disease was accentuated at the higher rates of lime.

The effect of serial planting on the phenological development of Lupinus angustifolius (cvv. Uniwhite, Uniharvest and Unicrop) and L. albus (cv. Ultra) was investigated in field plots at north-eastern Victoria. In 1973, Uniwhite was sown at 16 weekly intervals from May to September at one site: in 1974 Uniharvest, Unicrop and Ultra were planted at four locations, from early April to late September. Duration of the developmental phases-emergence to floral initiation, initiation to first flower, and first flower to last flower-was related to field measurements of temperature, photoperiod, and global radiation. Development of all cultivars from emergence to flowering was highly correlated with temperature and photoperiod (coefficients of determination from 49.5 per cent to 98.5 per cent). Our results suggested that photoperiod contributed to the duration of the flowering period. Unicrop and Ultra were quicker to initiate and flower than Uniharvest and Uniwhite, particularly from early plantings. Later planting reduced the duration of the post-initiation phases, particularly duration of flowering. The range of developmental adaptability exhibited by the four cultivars indicates that lupins could be grown over a large area of Victoria.