Foliar sprays of salicylic acid and jasmonic acid stimulate H+-ATPase activity of tonoplast, nutrient uptake and salt tolerance of soybean.

This research was conducted as factorial on the basis of randomized complete block design with three replications to evaluate the effects of salicylic acid (1 mM SA), jasmonic acid (0.5 mM JA) and SA+JA on H+-ATPase hydrolytic activity of tonoplast in soybean roots under 0, 4, 7 and 10 dS m-1 NaCl levels. The H+-ATPase hydrolytic activity of tonoplast was increased under 4 dS m-1, but with rising salinity up to 7 and 10 dS m-1, the activity of H+-ATPase and ATP content were decreased in root cells. Root growth, potassium, calcium, magnesium and iron contents in plant tissues were decreased, while sodium, manganese, zinc and copper contents were increased by salinity, leading to a reduction in chlorophyll content index (CCI), relative water content (RWC), plant biomass and grain yield of soybean. Treatment of plants with SA, JA and SA+JA improved H+-ATPase activity and ATP content in root cells. JA treatment also reduced root growth, thereby limited sodium uptake by roots and translocation to the shoots. Foliar spray of JA only increased magnesium and iron contents in plant tissues, with no significant effect on other cations. In contrast, SA and SA+JA improved root growth and enhanced most of the cations, CCI, RWC, plant biomass and consequently grain yield under different levels of salinity. The SA+JA was a superior treatment in diminishing the harmful effects of salinity on soybean plant performance, compared with individual application of these growth regulators.