Modulation in growth, gas exchange, and antioxidant activities of salt-stressed rice (Oryza sativa L.) genotypes by zinc fertilization

Salt stress poses a major threat against rice that is reinforced by Zn deficiency especially in calcareous and alkaline soils due to high pH, calcareousness, and climate of arid to semi-arid. The current study was conducted with the objective to ameliorate the salt stress impact through exogenous Zn application. There were four rice genotypes (BAS-2000, KSK-133, IR-6, and BAS-198) that were subjected to two salinity levels (control and 70 mM) in the presence of two levels of zinc (control and 15.00 mg kg(-1)). Results revealed that salinity stress adversely affected the biochemical, morphological, and physiological activities of all rice genotypes. The application of Zn significantly improved the crop performance both under saline and non-saline conditions. Studies further exhibited that KSK-133 is found as a leading genotype at salt-stressed conditions by showing less reduction in plant growth attributes, i.e., plant biomass, SPAD value, stomatal conductance, photosynthetic rate, transpiration rate, antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) activities, Zn concentration, and K: Na relative to percent of control treatment. The results of our experiment clearly indicated that under salt-stressed conditions, KSK-133 performed well than BAS-2000 and IR-6 while genotype BAS-198 was observed to be sensitive against salinity stress. In case of non-saline conditions by Zn application, BAS-2000 performed well compared with others.