Influence of foliar-applied salicylic acid on growth, gas-exchange characteristics, and chlorophyll fluorescence in citrus under saline conditions

Abstract

Salicylic acid (SA) is a common, plant-produced signal molecule that is responsible for inducing tolerance to a number of biotic and abiotic stresses. Our experiment was therefore conducted to test whether the application of SA at various concentrations (0, 0.10, 0.50, and 1.00 mM) as a foliar spray would protect citrus seedlings (Valencia orange/Bakraii) subjected to salt stress (0, 25, 50, and 75 mM NaCl). Growth parameters, leaf chlorophyll (Chl) content, relative water content (RWC), maximal quantum yield of PSII photochemistry (F v /F m ), and gas-exchange variables were negatively affected by salinity. In addition, leaf electrolyte leakage (EL) and proline content increased by salinity treatments. Application of SA increased net photosynthetic rate and proline content in salt stressed plants and may have contributed to the enhanced growth parameters. SA treated plants had greater Chl content and RWC compared with untreated plants when exposed to salt stress. F v /F m ratio and stomatal conductance were also significantly higher in SA treated plants under saline stress conditions. SA application reduced EL compared to untreated plants, indicating possible protection of integrity of the cellular membrane. It appeared that the best ameliorative remedies of SA were obtained when Valencia orange/Bakraii seedlings were sprayed by 0.50 and 1.00 mM solutions. Overall, the adverse effects of salt stress could be alleviated by exogenous application of SA.

Mitigation of the Impact of Vascular Wilt and Soil Hypoxia on Cape Gooseberry Plants by Foliar Application of Synthetic Elicitors

“…This may be because SA is related to the activation of cell division in the meristems and the improvement of the photosynthetic rate, carboxylase activity of the Rubisco enzyme, and membrane stability. In addition, this synthetic elicitor also increases phenols, chlorophyll, carbohydrates, and proline contents, and promotes the activity of antioxidant enzymes (Asgharei, 2015;Hayat et al, 2010;Khoshbakht and Su et al, 2018).…”

Effects of foliar applications of nitric oxide and spermidine on chlorophyll fluorescence, photosynthesis and antioxidant enzyme activities of citrus seedlings under salinity stress

“…Salinity causes various injuries in plants, such as tissue burning, yield reduction, and finally plant death (Romero-Aranda et al 2001), causes leaf senescence, reduction PSII activities (Khayyat et al 2016), enhances membrane permeability (Dhindsa et al 1981), nutritional imbalances, and toxicity (Khoshbakht et al 2014). NaCl inhibits photosynthetic rate (PN) as a consequence of osmotic stress, which leads to a decrease in water potential and stomatal conductance (g s ), sugar accumulation, which causes feedback inhibition, and ion toxicity (e.g., an excess of Na + and Cl -) accompanied by a reduction of K + and Ca 2+ (Khoshbakht and Asgharei 2015a). Moreover, salinity can cause oxidative stress through excessive production of reactive oxygen species (ROS), such as superoxide radical (O 2 • -), hydroxyl radicals ( • OH), and hydrogen peroxide (H 2 O 2 ) (Wu et al 2011).…”

Exogenous salicylic acid-induced nitric oxide regulates leaf water condition through root osmoregulation of maize seedlings under drought stress

“…Salicylic acid (SA) is regarded as an important plant growth regulator. It can regulate plant growth and development not only under non-stressed conditions, as well as under stressful environments (Kang et al 2013;He et al 2014;Khoshbakht and Asgharei 2015). It has been documented that SA enhanced the drought tolerance in wheat by increasing the contents of osmolytes (Loutfy et al 2012).…”