Nitrogen use efficiency and grain yield of lowland rice cultivars
1995
Willauer, J.L. III | Valdez, R.R. | Cruz, R.T. (International Rice Research Inst., Los Banos, Laguna (Philippines). Agronomy, Soils and Plant Physiology Div.)
Different cultivars of the same plant type vary in their response to different levels of applied nitrogen (N). PSB cultivars Rc2, Rc4, Rc6, Rc8, Rc10, Rc12, and Rc14 were grown on maligaya clay (Isohyperthermic chromic haplustert) with increasing nitrogen fertilizer levels (45, 90, and 135 kg/ha) during the 1994 dry and wet seasons to determine the optimum N level. The highest yield was observed using 90 kg N/ha for most cultivars. Grain yield increment for most cultivars was highest using 45 kg N/ha. Increasing the level of applied N resulted in a decreasing increment in grain yield. The decline in grain yield at high level of applied N was observed with PSB Rc4, Rc8, Rc10, and Rc14. The decrease was correlated with the variations in yield components. Decreasing N use efficiency at higher level of applied N was observed with varieties of similar plant type. N uptake difference was not significant between cultivars of the same plant type
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