Effects of Nitrogen on Biochemical indices of Some Winter Rice (Oryza sativa L.) Crop under Low Light Condition

Light is a critical natural resource for growth and development of rice crop. Rice grown in North East India especially Assam during kharif season (June-December) sufferes from natural low bright sunshine (800-900 hours i.e 50% of normal). On the otherhand, Nitrogen becomes a limiting nutritional factor. Because rice crop exhibits lower N use efficiency (≈33%) in subtropical regions (viz., North east India) due to heavy rainfall causing its loss by leaching or ammonia volatilization that contributes environmental pollution too. It's inquisitive to understand the physiological and biochemical changes in rice crop brought about by nitrogen under low light conditions. Therefore, a dose response study of N (0, 50, 100 kgha-1) on eight winter (kharif) rice genotypes Aki Sali, Senduri Sali, Rong Salpana, Bodumoni Sali, Kati Sali, Bordubi Sali, IR-8 (low light susceptible), and Swarna Prabha (low light tolerant) was performed applying N in splits as basal. In the study, 50 Kg Nha-1 was optimal in regulating most of the plant biochemical traits under low light condition. As such, Chlorophyll contents, NR activity, N content, NUE, Carbohydrate contents (Starch and Reducing sugar) were maximum at the optimum N level as compared to the control under low light condition.