Effect of flowering time on rate of dry matter accumulation, duration of filling period and total oil content in Brassica seeds

Development of seeds/siliqua originating from early and late flowers on main raceme was studied in two Brassica speceis sown on different dates in field for two seasons. The rate of dry matter accumulation in both seasons and through all sowings remained higher in late formed pods. This higher rate is due to higher temperature and longer photoperiod that existed during their development. Since seeds from late formed pods appeared at a faster rate, so had lesser degree days. The mean degree days were 728 and 851° Cd for late and early formed pods respectively. Linear regression showed a positive correlation between duration for seed filling period and degree days. The development span decrease by one day for decrease of every 11 and 8°Cd in early and late siliqua respectively. Duration of filling period from flower opening to maximum seed weight was more in early than late formed pods. This period was longer for early sown crops. Mean maximum dry weight of seeds through all planting dates and cultivars were 61.0 and 56.5 mg/siliqua for early and late formed pods respectively. Seeds in upper positioned pods on the main raceme had invariably low per cent oil content than lower positioned pods.