Relationship between thermal energy utilization efficiency and age of transplanted seedlings of gobhi sarson (Brassica napus L.)

Field experiments were conducted for two consecutive crop seasons of 2008–09 and 2007–10 at the research farm of the department of Agronomy, Punjab Agricultural University, Ludhiana to study the phenological development and thermal energy utilization efficiency of two canola gobhi sarson (Brassica napus L.) cultivars PAC 401 and composite variety GSC 6 under irrigated conditions. Treatments comprised of transplanting of 20 and 35 days old nurseries of hyola hybrid. Crop raised from older nursery (35 days) resulted in shorter vegetative phase of 49.5 days as compared to 54 days in the crop from 20 days old nursery. Hybrid PAC 401 took more number of days for attaining maturity than GSC 6 irrespective of age of transplanted nursery. Heat use efficiency of 35 days old transplanted nursery of PAC 401 for production of seed was higher than GSC 6. Cultivar GSC 6 was superior for young nursery. GSC 6 utilized more HTU for straw production. Crop raised from 35 days old nursery availed more heat units to reach crop maturity. A positive correlation was observed between seed yield and heat units availed. Proportion of the heat units availed for a particular phenophase remained almost unaltered irrespective of the age of nursery and cultivar.