Growth and yield pesponse of tranditional tall and improved semi-tall rice cultivars to moderate and high nitrogen, phosphorus and potassium levels

Morpho-physiological analysis of growth and yield in traditional tall and improved semi-tall rice cultivars grown at moderate and high NPK levels revealed that in all rice cultivars tested, high level ofNPK fertilization manifested significantly higher plant stature, tiller production, bioproductivity, leaf area index, leaf area ratio, crop growth rate, economic and biological productivity/ha/day, panicles/m², grain yield, straw yield and bioligical yield; whereas specific leaf weight, grains/panicle, foliage efficiency and harvest index were reduced drastically under high level of nutrients fertilization. Some physiological characters i.e. 1000 grain weight, pre and post anthesis dry matter production percentage, relative growth rate and net assimilation rate, however, were not affected much by high and moderate levels of nutrients application. Among diverse rice cultivars, the traditional tall were found superior to improved semi-tall in total biomass production, leaf area index, preanthesis dry matter production, biological productivity/ha/day, straw and biological yield regardless of NPK levels. The improved sem-itall cultivars, however proved to be better than traditional tall in grains/panicle, foliage efficiency, harvest indix, grain yield and post anthesis dry matter prodiction. Greater number of panicles/m² accompanied with low grains per panicle under high nutrients level. The traditional tall basmati cultivars proved to be promising in total biomass production m² both under moderate and high soil fertility levels, but manifested lower grain yield than semi-tall improved ones mainly because of poor conversion effeciency of biomass into grain under severe lodging, as the grain yield of basmati 370 was at par to semi-tall cultivars when protected from lodging.