Grain yield, root growth and N uptake of early duration rice varleties as influenced by nitrogen levels under rainfed upland

摘要

A field experiment was conducted during rainy season of 1995 and 1996 at IGAU, Raipur to find suitable early duration rice varieties and nitrogen level under rainfed upland condition. Among, the six varieties tested, NDR 1021, Poornima, Vandana andAnnada were found to be equally effective for grain yield and N uptake. The maximum N use efficiency (27.45 kg grain kg~(-1) N) was recorded in variety NDR 1021 which was followed by Vandana and Poornima. The significant increase in grain yield was supported by panicle bearing tillers, grains earhead~(-1) and test weight. On an average 89 percent roots of these varieties were accumulated in 0-10 cm soil depth, followed by 7.42 percent in 10-20 cm and 3.58 percent in 20-30 cm soil depth. The grain yieldand N uptake progressively increased with increasing levels of nitrogen upto 120 kg N ha~(-1). The nitrogen use efficiency, on the other hand, decreased with the increase in N levels. The regression equation for the estimation of grain yield at differentN levels are also estimated.