Journal of Soil and Plant Interactions

In drought stress conditions, besides the inhibition of water uptake, the plant nutrients availability and uptake are also limited. Proper nutrition is known as a management procedure for plant production under different environmental-stress conditions. Generally, the combined effects of drought and deficiency of potassium and zinc on plant water content and some physiological parameters reduce yield quantity and quality. This investigation was conducted to assess the interactive effect of different levels of potassium as KNO₃ (0.6, 3 and 6 mM) and zinc as ZnSO₄ (0, 1 and 2 μM), under drought stress conditions induced with PEG 6000 (0, 55 and 110 g/L PEG 6000) on some water status indices and physiological parameters of tomato in hydroponic culture. The results showed that interaction of drought, potassium and zinc on shoot and root dry weight, leaf chlorophyll and proline content and percentage of root ion leakage was significant. Both potassium and zinc improved water status of the plants however the effect of zinc on leaf water potential was not significant. Drought stress increased the chlorophyll content and decreased the sulfhydryl groups. Application of a high level of potassium in the nutrient solution increased root ion leakage.