Effects of sowing date and planting density on the structure and yield of autumn-sown, florally-determinate white lupins (Lupinus albus) in the United Kingdom

Abstract

SUMMARYThe effects of varying the sowing date (early September-late October) and plant density (14–70 seeds/m2) on the establishment, overwinter survival, structure and yield of an autumn-sown, florallydeterminate line (CH304/70) of the white lupin (Lupinus albus) were examined in three contrasting growing seasons between 1991 and 1994. Crops established well when sown in early September and were sufficiently cold-hardy to survive prolonged and extremely severe early winter frosts, but crops sown in late October either lost many plants or were destroyed completely. There was a strong interaction between sowing date and autumn weather on crop structure and yield. Late sowing and cold autumn weather restricted the number of mainstem leaves and first-order lateral branches on the plant, and decreased plant height and yield potential.Despite considerable differences between years in the weather during the summer and autumn, all crops were harvested in early September. Grain yields ranged from 0·3 to 4·5 t/ha depending on season, sowing date and plant density. Yields were strongly correlated with the number of podbearing axes and pods per m2 and, although actual yields differed depending on growing conditions, the same number of pod-bearing axes (100/m2) was required in each year to achieve maximum yield. The effects of sowing date and autumn weather on plant structure were well predicted by a simple developmental model that related vernalization and leaf development to post-sowing temperature.