Influence of Foliar Application of Hydrogen Peroxide on Gas Exchange, Photochemical Efficiency, and Growth of Soursop under Salt Stress

Hydrogen peroxide at low concentrations has been used as a salt stress attenuator because it induces a positive response in the antioxidant system of plants. This study aimed to assess the gas exchange, quantum yield, and development of soursop plants cv. Morada Nova grown with saline water irrigation and foliar hydrogen peroxide application. The experiment was carried out under greenhouse conditions using a randomized block design in a 4 x 4 factorial scheme corresponding to four levels of electrical conductivity of irrigation water, ECw (0.8, 1.6, 2.4, and 3.2 dS m(-1)), and four doses of hydrogen peroxide, H2O2 (0, 10, 20, and 30 mu M), with three replicates. The use of irrigation water with electrical conductivity above 0.8 dS m(-1) inhibited stomatal conductance, internal CO2 concentration, transpiration, maximum fluorescence, crown height, and vegetative vigor index of the Morada Nova cultivar of soursop. Compared to untreated plants, the hydrogen peroxide concentration of 30 mu M resulted in greater stomatal conductance. Water salinity of 0.8 dS m(-1) with hydrogen peroxide concentrations of 16 and 13 mu M resulted in the highest variable fluorescence and quantum efficiency of photosystem II, respectively, of soursop plants cv. Morada Nova at 210 days after transplantation.

Automated summary

This study aimed to assess the effects of saline water irrigation and foliar hydrogen peroxide application on the gas exchange, quantum yield, and development of soursop plants. The results showed that high electrical conductivity of irrigation water inhibited stomatal conductance, internal CO2 concentration, transpiration, maximum fluorescence, crown height, and vegetative vigor index of the plants. However, applying hydrogen peroxide at a concentration of 30 μM resulted in increased stomatal conductance.