Heat unit requirement of mustard (Brassica Juncea L.) under different thermal regimes and irrigated conditions of Namsai region of Arunachal Pradesh

Abstract

Field experiments were conducted under Arunachal University of Studies, Namsai, Arunachal Pradesh during 2017-18 to 2018-19 on mustard crop was sown on three dates (10th October, 20th October, and 30th October) with three irrigation treatments. The results indicated that the number of days required for attaining different phenological stages decreased with the delay in sowing. For all the phenological stages, crop sown on 10th October consumed higher heat units and consequently resulted in higher yield and heat use efficiency (HUE) than that of another sowing. However, higher pheno-thermal index (PTI) values were observed for the late sown crop i.e. 10th October. Further, among the irrigation treatments, three irrigations throughout the growing period showed an increase in days to physiological maturity as well as heat units and HUE for grain and biological yield as compared to other treatments. Three irrigations throughout the growing period increased the grain yield by 72 percent and biological yield by 54 percent than that of one irrigation at before flowering stage. The GDD also showed a highly significant positive correlation with grain and biological yield. Therefore, it may be used for forecasting the phenological stages and yield under different sowing date and stage-based irrigation scheduling for mustard.