EFFECTS OF DIFFERENT SOWING DATES ON THE PHENOLOGY AND ACCUMULATED HEAT UNITS IN THREE RAPESEED (BRASSICA CAMPESTRIS L.) VARIETIES

A field experiment was carried out to study the effect of sowing dates on phenology and accumulated heat units of rapeseed (Brassica campestris L.). Seeds of three varieties (BARI Sarisha-14, BINA Sarisha-5 and BINA Sarisha-6) were sown on four different dates from October to December (S-1-18 October, S-2-2 November, S-3-17 November and S-4-3 December). The results indicated that the number of days required to attain different phenological stages decreased with delay in 'sowing. For all the phenological stages, S-1 required higher heat units than that of other sowings. The plants of SI used heat more efficiently than S-2, S-3 and S-4. At the earlier phenological stages, phenothermal index decreased with delay in sowing, but increased at the later stages.