Salicylic acid and trehalose attenuate salt toxicity in Brassica juncea L. by activating the stress defense mechanism.

Two significant soil degradation processes that pose a hazard to our ecosystems are soil salinization and sodification. The information on potential of salicylic acid (SA) and trehalose (Tre) to induce abiotic stress signaling and triggers physio-biochemical responses in crop plants is limited. Therefore, the present study was aimed to investigate the efficacy of 5 µM SA and/or 10 mM Tre in improving the growth, photosynthesis, ion homeostasis, nutrient acquisition, antioxidant defense system and yield of mustard plants growing under sodium chloride (NaCl) stress (0, 50, 100 and 150 mM NaCl). The data showed that increasing NaCl stress concentration decreased growth, photosynthesis, membrane permeability, ion homeostasis and yield in a dose-dependent manner while increasing considerably enzymatic antioxidant enzyme activities, compatible solute accumulation, sodium ion and oxidative stress biomarkers linearly with increasing NaCl stress concentration. The spray of SA, Tre, and SA + Tre played diversified roles in enhancing NaCl stress tolerance in mustard at morpho-physiological and biochemical levels. The combined SA + Tre application proved best and completely neutralized the NaCl stress-induced suppression in growth, photosynthesis, ion homeostasis, nutrient acquisition and yield by significantly enhancing the activities of enzymatic antioxidants, compatible solutes accumulation, water status and membrane permeability, while reducing considerably osmotic stress, reactive oxygen species generation, lipid peroxidation, cell death and sodium uptake in mustard. The SA + Tre application enhanced relative water content by 23%, net photosynthetic rate by 48%, superoxide dismutase activity by 51% and seed yield per plant by 64%, while decreased superoxide anion content by 26%, sodium ion content by 36% and malondialdehyde content by 25% over 0 mM NaCl treatment. Our findings indicate that the co-application of SA + Tre can be a suitable approach to palliate the ill effect of NaCl stress in mustard plants.

Plant growth regulators mediated mitigation of salt-induced toxicities in mustard (Brassica juncea L.) by modifying the inherent defense system.

Salt stress is one of the common environmental threats to crop growth, development, and productivity. Plant growth regulators (PGRs) are natural messengers and are known to play pivotal roles at different stages of the growth and development of plants under various environmental conditions. Keeping in mind the importance of PGRs in stress management, a factorial randomized pot experiment was conducted to evaluate the efficiency of three selected PGRs, namely gibberellic acid (GA3), salicylic acid (SA) and triacontanol (Tria) for the amelioration of NaCl stress in mustard. Plants were subjected to four concentrations of NaCl (0, 50, 100 and 150 mM). Two foliar sprays of PGRs (GA3, SA and Tria), each at 5 µM were applied to the foliage of plants using a hand sprayer. The increasing levels of NaCl decreased growth, physio-biochemical, histochemical and yield parameters in a dose-dependent manner while increasing activities of antioxidant enzymes, contents of osmolytes and oxidative stress biomarkers linearly with increasing levels of NaCl. The spray of GA3, SA and Tria under stressed-free and stressed conditions improved the aforesaid attributes while decreasing the generation of stress biomarkers. Of sprayed PGRs, SA proved to be the best for alleviating the adverse effect of NaCl stress. Furthermore, it provides experimental data for its possible biotechnological applications in mustard crops exposed to high concentrations of salinity and possibly to other environmental stresses which have associated oxidative stress.

Triacontanol as a dynamic growth regulator for plants under diverse environmental conditions.

Triacontanol (TRIA) being an endogenous plant growth regulator facilitates numerous plant metabolic activities leading to better growth and development. Moreover, TRIA plays essential roles in alleviating the stress-accrued alterations in crop plants via modulating the activation of the stress tolerance mechanisms. The present article critically focuses on the role of exogenously applied TRIA in morpho-physiology and biochemistry of plants for example, in terms of growth, photosynthesis, enzymatic activity, biofuel synthesis, yield and quality under normal and stressful conditions. This article also enlightens the mode of action of TRIA and its interaction with other phytohormones in regulating the physio-biochemical processes in counteracting the stress-induced damages in plants.