Phenology, heat unit accumulation and dry matter partitioning behavior of two rice cultivars transplanted on different dates.

摘要

Field studies were conducted in Punjab, India, during the 2007 and 2008 kharif seasons, to determine the phenological behaviour, heat requirements and dry matter partitioning of long (PR 118) and medium (PAU 201) duration rice cultivars under different transplanting dates. The treatments comrised 2 rice cultivars (PR 118 and PAU 201) and transplanting dates (15 and 25 June and 5 July). Data were recorded on days to 50 and 100% flowering, dry matter accumulation, growing degree-days and thermal units and yield and its components. Results showed that PR 118 took 7 and 9 days more to attain 50% flowering and maturity, while PAU 201 took 85 and 106 days to attain 100% flowering and maturity, respectively. PR 118 used up more thermal units to mature than PAU 201. A 5.4% reduction in yield was recorded in PR 118 when transplanting was delayed from 25 June to 5 July, while PAU 201 registered almost equal grain yields even under delayed transplanting (5 July).