Physiological evaluation of nitrogen use efficiency of different rice varieties
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Date
2007-05
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Rice not only forms the mainstay of diet but also is the livelihood for a large percent of world’s population. Nitrogen directly affects yield contributing parameters as it is an important constituent of various biomolecules. Rice plant requires nitrogen during vegetative and reproductive growth phases which is made available through soil mineralization and nitrogen fertilizer application.
Rice accounts for approx 35 % of worldwide nitrogen used, however nitrogen uptake and nitrogen use efficiency of rice is respectively between 30-35 % and 25-30%. Increase in nitrogen uptake is highly correlated with the grain yield, hence to meet the world’s ever growing rice demand, appropriate fertilizer management practices are a must.
Plant parameters were undertaken with the idea to evaluate nitrogen use efficiency of nine rice varieties HYVs Ajaya, BPT-5204, NDR 359, aromotic varieties Pusa Basmati-1, Tarouri Basmati, Vasumati and hybrid varieties KRH 2, PA 6444, PHB 71 under three nitrogen treatments viz. urea @ 0, 100 and 200kg N/ha..
The morphological and physiological parameters viz plant height, number of leaves, LAI, TDM, LAR and NAR gave maximum values at N-200 and minimum at N-0. RGR gave maximum values at N-100 while RLAGR and HI were found maximum at N-0. SPAD gave maximum value at N-200 (33.73 at Tmax and 33.72 at flowering for HYV BPT-5204) & minimum at N-0 (26.23 at Tmax and 29.93 at flowering for aromatic rice variety Tarouri Basmati). NRA was maximum for hybrid PHB 71 at N-100 & minimum for aromatic rice variety Vasumati at N-0. Grain protein was also recorded maximum at N-100 (for hybrid PHB 71) & minimum at N-0 (for HYV NDR-359). The nitrogen estimated in plant parts at Tmax was recorded maximum at N-200 (3.54 % for hybrid PHB 71) & minimum at N-0 (1.09 % for BPT-5204), however at flowering no specific correlation was found among the nitrogen treatments & percentage nitrogen estimated in plant parts. The residual soil nitrogen before fertilizer application was constant in whole field. After fertilizer application, it increased with increasing amount of nitrogen applied to the field.
Most of the yield components like primary and secondary branches per panicle, spikelet per square metre, number of grains per panicle, panicle TDM, grain yield and straw weight increased linearly with nitrogen applied. The number of panicles per square metre were recorded maximum for N-100 (475 for HYV BPT-5204) & minimum for N-0 (237.5 for NDR-359). Overall, the quantitative characters were recorded maximum at N-200 while the qualitative characters were recorded maximum at N-100. Hence, to obtain higher NUE, nitrogen should be applied @ 100 kg/ha. Further, the studies can be exploited in nutrient management in different rice varieties to enhance nitrogen efficiency.
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