Department of Soil Science and Agricutural Chemistry, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai, 625104.
Present address:1 Department of Soil Science and Agricultural Chemistry, Annamalai University, Annamalainagar, Tamil Nadu, 608002.
A field experiment was conducted to find out the relationship between N uptake and grain yield of 12 rice varieties of three different duration groups i.e. short, medium and long with a common dose of 100 kg N ha−1 The N uptake pattern of the rice crop at different stages was monitored besides recording the yield data. Correlation coefficients were established between N uptake and grain yield. From this, it was found that, multiplying the duration of the crop with a Nitrogen Varietal Index (NVI) i.e. 0.6 gave the period of plant sampling for predicting critical N concentration which needs to be maintained with supplemental fertilizer N application.
Nitrogen varietal index, N uptake, grain yield, rice
