Field environment studies on lupins. 2. The effects of time of planting on dry matter partition and yield components of Lupinus angustifolius L

Dry matter partition, seed yield, and yield components were examined in two lupin cultivars at eight planting times. Dry matter production and seed yield both declined with later planting primarily as a result of the foreshortened growing season which reduced the production of lateral branches and consequently the number of inflorescences per plant. For a given inflorescence, planting date appeared to have no systematic effect on pod number, although pod numbers on the main stem inflorescence varied with planting date. Mean seed weight declined slightly with later planting. Unicrop, the earlier-flowering cultivar, gave higher seed yields owing to greater development of higher order lateral branches and heavier individual seeds. Flowering began when only 17-25 % of maximum dry matter had accumulated, and subsequent dry matter partition between main stem and successive orders of lateral branches emphasized the characteristic structural development of the lupin. Seed filling occurred in the last 4-6 weeks of growth when vegetative development had nearly ceased, and was almost concurrent in both cultivars, all planting times and all lateral orders irrespective of the time of pod set.