Growth pattern and yield of NERICA 1 and NERICA 4 rice varieties as a function of split nitrogen application at Tsukuba, East Japan

摘要

The study was conducted with the aim of investigating the effect of split application of nitrogen on growth and yield of NERICA 1 and NERICA 4 rice varieties at Tsukuba International Center, Japan from April to September 2013 cropping season. The varieties were investigated for establishment, plant height, tiller number, SPAD value, shoot dry matter, panicle dry matter, nitrogen uptake, panicle number, spikelet number, panicle length, ripening ratio, thousand grain weight, harvest index and paddy yield. The result showed that NERICA 1 had significantly greater establishment percentage, shoot dry matter, panicle length and thousand grain weight than NERICA 4, but its leaves were significantly (p<0.05) less green than the latter after 55 days of sowing. Dividing 80kg N ha~(-1) into two and applying half rate at sowing as basal and top dressing at panicle initiation gave significantly more green leaves than either at once application of full rate or half rate as basal and half rate top dressing at heading applications from 90-115 days after sowing. However, application of half rate of 80kg N ha~(-1) at sowing and heading time produced significantly (p<0.05) more green leaves than at once and half as basal and at panicle initiation after 115 days of sowing. It also produced significantly longer panicles than the other two modes of N applications. In all of the evaluated parameters, varieties and split nitrogen applications failed to show significant (p>0.05) interaction. Splitting 80kg N ha~(-1) in to two and applying half of it at sowing and the remaining half at panicle initiation as well as applying half of it at sowing and the remaining half at heading time increase panicle length compared to applying full rate at once during sowing.