Seedling age, plant density and nitrogen levels on days to 50 per cent flowering, crop duration and spikelet sterility percentage on short duration low land rice

摘要

As transplanting is the common practice in the cultivation of rice (Oryza sativa L.) age of seedling at planting is crucial for realizing the yield potential of short duration lowland rice. In double cropped areas under Periyar Vaigai Command area,a short duration rice is being raised during first season (Kharif) from June to September followed by a medium duration rice in second season (Rabi) during October to February. Constraints like delayed release of water from the normal date due to inadequate rainfall, non-availability of adequate labourers during the peak period of transplanting and non-availability of inputs, farmers are resort to late planting with aged seedlings. Delayed transplanting of rice reduces the crop yield and also affected land preparation and planting of succeeding crop. Unlike medium and long duration rice cultivars total duration of the crop from sowing to maturity found to increase with increased seedling age at planting in short duration rice cultivars (Kamadi et al, 1991). The efforts are made in this study to find out effects of seedling age, plant density and nitrogen levels on crop duration and yield in short duration lowland rice.