Foliar Application of Salicylic Acid Improves Water Stress Tolerance in Conocarpus erectus L. and Populus deltoides L. Saplings: Evidence from Morphological, Physiological, and Biochemical Changes

Abstract

Reforestation efforts are being challenged as water stress is hampering the sapling growth and survival in arid to semiarid regions. A controlled experiment was conducted to evaluate the effect of foliar application of salicylic acid (SA) on water stress tolerance of Conocarpus erectus and Populus deltoides. Saplings were watered at 90%, 60%, and 30% of field capacity (FC), and half of the saplings under 60% and 30% FC were sprayed with 1.0 mM SA. Results indicated that dry weight production decreased significantly in Populus deltoides under both water deficit conditions, and leaf gas exchange parameters decreased significantly in both the species under both soil water deficit conditions. Foliar application of SA resulted in a significant increase in leaf gas exchange parameters, and compatible solutes, thereby increasing the dry weight production in both of the species under soil water deficit. Oxidative stress (hydrogen peroxide and superoxide anions) increased under soil water deficit and decreased after the foliar application of SA and was parallel to the increased antioxidant enzymes activity (superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase). Therefore, it can be concluded that foliar application of 1.0 mM SA can significantly improve the water stress tolerance in both species, however, positive impacts of SA application were higher in Conocarpus erectus due to improved photosynthetic capacity and increased antioxidant enzyme activity.

Salicylic Acid Improves Antioxidant Defense System and Photosynthetic Performance in Aristotelia chilensis Plants Subjected to Moderate Drought Stress

“…Currently, SA has been suggested as an important molecule involved in ameliorating plant drought stress [ 38 , 39 , 40 , 63 ]. However, the physiological and biochemical mechanisms involved on drought stress tolerance induced by SA in plants have not been well understood [ 42 , 43 ]. Some reports have shown that SA improves SOD and APX activities and leaf gas exchange in Conocarpus erectus , Populus deltoids, and Olea europaea plants subjected to drought stress [ 38 , 42 ].…”

“…However, the physiological and biochemical mechanisms involved on drought stress tolerance induced by SA in plants have not been well understood [ 42 , 43 ]. Some reports have shown that SA improves SOD and APX activities and leaf gas exchange in Conocarpus erectus , Populus deltoids, and Olea europaea plants subjected to drought stress [ 38 , 42 ]. Therefore, we hypothesized that SA application triggers enzymatic and non-enzymatic antioxidant mechanisms, ameliorating oxidative stress and improving photosynthesis performance and plant growth in A. chilensis plants subjected to drought stress.…”

“…For example, Chen et al [ 41 ] showed that SA application increased CO 2 assimilation and plant growth in drought-stressed Zoysia japonica plants. Currently, Zafar et al [ 42 ] reported that leaf gas exchange, SOD and APX activities, and dry weight accumulation were improved by SA application in Conocarpus erectus and Populus deltoides plants subjected to drought stress. Therefore, SA is a critical plant hormone that regulates the activation of biotic and abiotic stress defense.…”

“…Therefore, SA is a critical plant hormone that regulates the activation of biotic and abiotic stress defense. However, the physiological and biochemical mechanisms involved in drought stress tolerance induced by SA in plants have not been well understood [ 42 , 43 ].…”

Jasmonic Acid Boosts Physio-Biochemical Activities in Grewia asiatica L. under Drought Stress

“…A study by Asensio et al [ 27 ] reported that the exogenous application of JA resulted in an improvement in CO 2 uptake in drought-exposed Zoysia japonica plants. In addition, exogenous JA application has also been reported to increase the antioxidant mechanism and reduce the level of lipid peroxidation in drought-stressed maize plants [ 28 ]. Therefore, JA application can enhance the growth and development of plants by providing protection against biotic and abiotic stress [ 29 ].…”