Interactive effect of potassium and spermidine protects growth, photosynthesis and chlorophyll biosynthesis in Vigna angularis from salinity induced damage by up-regulating the tolerance mechanisms

Pot experiments were conducted to evaluate the role of potassium (100 mg KCl / kg soil) and the spermidine (100 mu M Spd) in regulation of growth, chlorophyll synthesis and photosynthesis in Vigna angularis under salinity stress (100 mM NaCl). Salinity declined chlorophyll synthesis by causing a significant decline in the synthesis of delta-amino levulinic acid (ALA), prototoporphyrin IX (Proto IX) and Mg-prototoporphyrin IX (Mg-Proto IX), however application of K and Spd alone as well as combinedly alleviated the decline to considerable extent. Further, K and Spd treated plants exhibited a significant decline in reactive oxygen species and the lipid peroxidation and such effects were also obvious under salinity stress. Photosynthetic rate, stomatal conductance, intercellular CO2 concentration, Fv/Fm and photochemical quenching increased significantly due to K and Spd application, and salinity induced alleviation of the decline was maximal due to combined K and Spd treatment. Up-regulation of antioxidant enzymes activity, increased content of ascorbic acid and glutathione (GSH), and the accumulation of compatible osmolytes due to K and Spd application strengthened the tolerance against the salinity stress thereby lessening the oxidative effects considerably. Accumulation of phenols and flavonoids increased significantly due to application of K and Spd. Salinity caused significant increase in Na however K and Spd application induced a significant decline concomitant with increase in K content reflecting in decreased Na/K. Results suggest that K and Spd application protect the growth and photosynthesis from salinity induced oxidative damage by up-regulating the ion homeostasis, antioxidant system, osmolyte accumulation and secondary metabolite synthesis.

Automated summary

In this study, pot experiments were conducted to investigate the effects of potassium and spermidine on the growth, chlorophyll synthesis, and photosynthesis of Vigna angularis under salinity stress. The results showed that the application of potassium and spermidine alleviated the decline in chlorophyll synthesis caused by salinity stress. Additionally, these treatments enhanced the antioxidant system, osmolyte accumulation, and secondary metabolite synthesis, leading to increased tolerance against salinity-induced oxidative damage. Overall, our findings suggest that potassium and spermidine play a crucial role in protecting the growth and photosynthesis of Vigna angularis under salt stress.