Interactive Effects of Irrigation Scheduling and Sulphur Fertilization on Growth, Water use Efficiency, Yield and Oil Content of Indian Mustard (Brassica juncea L.) under Irrigated Conditions in Assam, India

Abstract

The experiment was carried out during the rabi season of 2019-20 at the Instructional-cum-Research Farm of Assam Agricultural University, Jorhat, to evaluate the effects of irrigation scheduling and sulphur fertilisation on growth parameters, crop growth rate (CGR), water use efficiency, yield, and oil content of Indian mustard (Brassica juncea L.) under irrigated conditions in Assam. The experiment was laid out in a split-plot design with two factors, viz., irrigation scheduling and sulphur fertilisation, each at different levels, with three replications. The treatments comprised six irrigation schedules, viz., I0 - rainfed, I1 - irrigation at 25-30 DAS, I2 - irrigation at flowering (F), I3 - irrigation at 25-30 DAS + flowering, I4 - irrigation at 25-30 DAS + siliquae formation (SF), and I5 - irrigation at 25-30 DAS + flowering + siliquae formation, and three sulphur levels, viz., S0 - no application (control), S1 - 20 kg ha-1, and S2 - 40 kg ha-1. The results revealed that irrigation scheduling significantly influenced growth parameters, crop growth rate, water use, and yield attributes of Indian mustard. Three irrigations at 25-30 DAS + flowering + siliquae formation (I5) and two irrigations at 25-30 DAS + flowering (I3) or 25-30 DAS + siliquae formation (I4) produced statistically at-par values for plant height at harvest, dry matter accumulation at 50 and 75 DAS, crop growth rate during 25-50 and 50-75 DAS, and branches plant-1, and these values were higher than those recorded with one irrigation and rainfed conditions. The I5 schedule resulted in higher evapotranspiration and total water use than I3 and I4, but recorded the lowest crop and field water use efficiencies. Plant height at 60 DAS and harvest, dry matter accumulation at 50 and 75 DAS, crop growth rate during 25-50 DAS, 50-75 DAS, and 75 DAS to harvest, and branches plant-1 were highest with 40 kg S ha-1, which was statistically at par with 20 kg S ha-1 and significantly higher than the control. Although evapotranspiration and total water use varied little among sulphur levels, crop and field water use efficiencies were comparatively higher with 40 and 20 kg S ha-1 than with the control.