Effectiveness of potassium sulfate in mitigating salt-induced adverse effects on different physio-biochemical attributes in sunflower (Helianthus annuus L.)

To assess whether foliar application of K + S as potassium sulfate (K2SO4) could alleviate the adverse effects of salt on sunflower (Helianthus annuus L. cv. SF-187) plants, a greenhouse experiment was conducted. There were two NaCl levls (0 and 150 mM) applied to the growth medium and six levels of K + S as K2SO4 (NS (no spray), WS (spray of water + 0.1% Tween 20 solution), 0.5% K + 0.21% S, 1.0% K + 0.41% S, 1.5% K + 0.62% S, and 2.0% K + 0.82% S in 0.1% Tween-20 solution) applied two times foliarly to non-stressed and salt-stressed sunflower plants. Salt stress markedly repressed the growth, yield, photosynthetic pigments, water relations and photosynthetic attributes, quantum yield (F-v/F-m), leaf and root K+, Mg2+, P, Ca2+, N as well as K+/Na+ ratios, while it enhanced the cell membrane permeability, and leaf and root Na+ and Cl- concentrations. Foliar application of potassium sulfate significantly improved growth, achene yield, photosynthetic and transpiration rates, stomatal conductance, water use efficiency, leaf turgor and enhanced shoot and leaf K+ of the salt-stressed sunflower plants, but it did not improve leaf and root Na+, Cl-, Mg2+, P, Ca2+, N as well as K+/Na+ ratios. The most effective dose of K + S for improving growth and achene yield was found to be 1.5% K+0.62% S and 1% K+0.41% S, respectively. Improvement in growth of sunflower plants due to exogenously applied K2SO4 was found to be linked to enhanced Photosynthetic capacity, water use efficiency, leaf turgor and relative water content. (C) 2008 Elsevier GmbH. All rights reserved.