Deficit Irrigation Scheduling and Superabsorbent Polymer‐ Hydrogel Enhance Seed Yield, Water Productivity and Economics of Indian Mustard Under Semi‐Arid Ecologies

Abstract

Oilseed brassicas are extensively grown in the water‐stressed ecologies of India. Sufficient irrigation, deficit irrigation scheduling (DIS) with limited irrigation water and rainfed (no irrigation) conditions were assessed with and without the use of superabsorbent polymer‐hydrogel (SAP‐hydrogel) under a micro‐sprinkler irrigation system (MIS) for Indian mustard. Irrigation scheduling at an irrigation water/cumulative pan evaporation ratio (IW/CPE) of 0.8, 0.6 and 0.4, along with use of SAP‐hydrogel, produced almost equal dry matter per plant (113, 115 and 109 g plant −1 ), which was, however, significantly higher ( P ≤ 0.05) over rainfed (86 g plant −1 ). The seed yield under DIS (0.6 IW/CPE) increased by 39.3% over rainfed + hydrogel (HG). Also, the seed yield obtained under irrigation scheduling at a ratio of 0.4 IW/CPE was found to be similar to that obtained in rainfed + HG treatment. A similar water productivity (WP) of 10 kg ha −1 mm −1 was obtained with DIS at 0.4 IW/CPE + HG and at 0.8 IW/CPE‐HG; however, a higher total water productivity (WP t ) was recorded under DIS at 0.6 and 0.4 IW/CPE + HG (23 and 29 kg ha −1 mm −1 , respectively) over the same irrigation schedules excluding HG. The economics of HG application under DIS was better due to higher net returns, although the highest B : C ratio (1.92) was recorded in DIS (0.4 IW/CPE), trailed by irrigation scheduling at IW/CPE 0.8 and 0.6. Overall, it could be concluded that DIS through micro‐sprinkler and use of HG enhanced seed, oil, water productivity and energy dynamics under water‐constrained conditions in semi‐arid ecologies. © 2019 John Wiley & Sons, Ltd.

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