Role of H2O2 on photosynthetic characteristics of soybean genotypes under low water input

Soybean is subjected to abiotic stresses that immensely affect its productivity during its lifespan and threaten food security globally. Recent research recommends that chemical substances could be applied to plants as an alternative to traditional agriculture to better abide abiotic stresses. Hydrogen peroxide (H2O2) is a potential agent that can serve for this purpose. Up to today, responses of exogenous H2O2 on photosynthetic machinery in plants exposed to drought is poorly investigated. Therefore, the effects of exogenous low dose H2O2 on plant chlorophyll fluorescence in two soy bean genotypes (Glycine max L. Merrill), 537 (tolerant) and 520 (susceptible), under drought were evaluated. Drought which we had found significantly reduced water potential of leaves and photosynthetic pigment concentration in two genotypes, did not cause change in Fv/Fm and ΦPSII of tolerant genotype, contrarily subsided qP and ETR values. However, Fv/Fm, ΦPSII, qP and ETR failed in susceptible genotypes under drought. Increases in NPQ were determined under stress in both genotypes. Exogenous H2O2 mitigated the drought-induced impairment in photosystem II efficiency in both genotypes. This data indicates that low dose H2O2 further enhanced the tolerance to drought via regulation of the photochemical process in both genotypes.