Assessment of irrigation and nutrient effects on growth, yield and water use efficiency of Indian mustard (Brassica juncea) in central India

A field experiment was conducted at the Indian Institute of Soil Science, Bhopal, India to study the effect of combinations of amount of irrigation water and nutrient applications on crop growth, evapotranspiration (ET), yield and water use efficiency (WUE) of Indian mustard on a heavy clay soil in central India. Three irrigation regimes, viz. 60 mm presowing and no post-sowing irrigation (I-60), 60 mm pre-sowing plus 60 mm post-sowing irrigation at flowering (I-120), and 60 mm pre-sowing plus 60 mm post-sowing irrigation at rosette and at flowering stage (I-180); and three nutrient application treatments, viz. no fertilizer/manure (F-0), 100% NPK, i.e., total N, P and K rates of 60, 13.1 and 16.6 kg ha(-1), respectively (F-100) and 100% NPK plus 10 Mg ha(-1) farmyard manure (F100M10) were tested in a split-plot design. The experiment was conducted for three consecutive seasons. The results revealed that treatment combinations of I-180 x F100M10, I-120 x F100M10 and I-180 x F-100 maintained significantly greater leaf area index (LAI), above-ground dry matter (DM), ET, seed and biomass yield of the crop than other combinations. The duration of a LAI of >= 2.5 was more in F-100 and F100M10 than in F-0. Under I-120, LAI remained >= 2.5 for 8 and 22 days in F-100 and F100M10, respectively. This leaf area duration increased to 28 and 39 days in the corresponding nutrient treatments under I-180. The root length, mass and volume densities were significantly higher in I-180 than I-120 and I-60, and in F100M10 than F-100 and F-0. For a particular irrigation regime, ET increased significantly in F-100 and F100M10 compared to F0. The maximum seed yield of 1736 kg ha-1 was recorded in I-180 x F100M10; and the seed yields under I-120 x F100M10 (1440 kg ha(-1)) and I-180 x F-100 (1431 kg ha(-1)) did not vary significantly. The WUEseed and WUEbiomass decreased with the increase in amount of irrigation water. On the contrary, these WUE parameters increased in F-100 and F100M10 compared to F-0. The regression relationships of root length density on ET, and yield (both seed and biomass yield) on ET could be described by linear. Thus, I-180 x F100M10 is the best combination; and as the crop response to I-120 x F100M10 and I-180 x F-100 was similar, this study concludes that application of organic manure along with 100% NPK fertilizers could reduce the need for one post-sowing irrigation without compromising the yield of this crop under deficit irrigation. (c) 2006 Elsevier B.V. All rights reserved.