Abstract:
The response of grain yield, yield components and grain quality of B. campestris and B. napus cultivars to planting date for two seasons at three locations from the north-western slopes to the northern tablelands of New South Wales are reported. The planting date that gave the highest yield varied between species and locations. The two species differed in the way yield components compensated for each other. For example, in B. campestris, yield variation was related to plant population and individual seed weight; in B. napus, both the number of pods per plant and the number of seeds per pod influenced yield. The oil content was highest in early plantings, decreased in later plantings, and was inversely related to protein content. The oil content was also inversely related to mean daily temperature during the grain-filling period. The northern tablelands was a more favourable region for rapeseed production than the northwestern slopes in terms of both grain yield and oil content. Implications of changes in the primary components of yield which are responsible for yield variations with planting date are discussed in relation to breeding objectives for rapeseed cultivar improvement. ____________________ *Part 11, Aust. J. Agric. Res., 29: 711 (1978).