The combined effects of phosphorus and zinc on evapotranspiration, leaf water potential, water use efficiency and tuber attributes of potato under water deficit conditions

This study was conducted for evaluating the combined effect of soil moisture, phosphorus (P) and zinc (Zn) levels on crop evapotranspiration (ET), leaf water potential (LWP), water use efficiency (WUE) and various tuber attributes of potato (Solanum tuberosum L. cv. Agria) under greenhouse conditions. This investigation was conducted as a factorial experiment based on randomized complete blocks design with Zn at three levels (0, 10 and 20 mg Zn per kg dry soil as ZnSO4·7H2O), P at three levels (0, 30 and 60 mg P per kg dry soil as Ca(H2PO4)2·H2O) and soil moisture at three levels (0.5 FC-0.6 FC, 0.7 FC-0.8 FC and 0.9 FC-FC) using three replications. The various attributes of potato tubers including tuber numbers, dry matter content (DM), yield, WUE and indicators of water deficit stress intensity (ET and LWP) were measured routinely during the crop growth period. The results showed that the water deficit stress resulted in a significant decrease in ET, tuber numbers, yield and WUE. Application of P significantly increased the ET, tuber numbers and yield and Zn application significantly affected the tuber numbers. The P × soil moisture interaction effect was significant for ET, LWP, tuber numbers and yield. While the Zn × soil moisture interaction was significant only for yield. The results showed that the two way interactions of Zn, P and soil moisture were mainly synergistic on the most of above mentioned attributes. In general, to achieve the optimum yield of potato tubers in similar soils, application of 10 mg Zn and 30 mg P per kg of dry soil could be recommended under full-irrigated conditions. The regression analysis showed that the yield of potato was increased by application of P under water deficit conditions.