Management of nitrogen for enhancing physiological efficiency in upland rice (Oryza sativa L.) under water stress condition

Abstract

Upland rice productivity is adversely affected by abiotic factors, particularly water stress condition. Rice genotypes may vary in nitrogen uptake and its use efficiency (NUE) for grain yield under drought stress. Real Time Nitrogen Management (RTNM) is one of the important techniques used for augmenting NUE in rice. In the RTNM approach, certain amount of fertilizer is applied only when leaf nitrogen content is below a critical level judged by SPAD values using a chlorophyll meter. In the study, nitrogen was applied in splits up to 130 kg ha-1 in total based on the SPAD values of rice leaves under simulated water stress condition (No water+ 5000ppm of 6000PEG spray at tillering and heading stages against normal irrigation. Five indigenous upland rice genotypes viz. Mairen ke-er, Soksu joha, Soksu bara, Chubok bara, Bijor soksu and one developed variety i.e. Inglongkiri were collected from RARS, Diphu (Assam) to evaluate for their yield potential using RTNM approach under water stress condition. In the study, Inglongkiri, was found to be physiologically efficient as compared to the other varieties. The variety is characterized by higher total N uptake in leaf tissues (71.8%), NUE (25.8%), Harvest index (43.5%), and the lowest reduction in grain yield (1.6%) under water stress condition.