Effects of sodium nitroprusside on some physiological and histological responses of pepper plants exposed to salt stress

Salinity exhibits many constraints in vegetable growing. Exogenous applications should be performed in growing in order to mitigate salinity damage. This study examined some physiological and histological properties of young pepper (Capsicum annuum L.) 'cetinel' plants exposed to salt stress by applying different doses of sodium nitroprusside (SNP). Seedlings were transplanted into pots and salt application was started after 6 d. One day before salt stress, three different doses of SNP (12.5, 25.0 and 50.0 mu M) were applied as a solution to the roots, excluding control and salt (NaCl) application. Then, 150 mM salinity was applied to all plants except the control. The experiment was terminated 35 d after the salinity treatment. At the end of the study, many histological and physiological parameters were evaluated. Plant growth, leaf relative water content (LRWC), total chlorophyll and carotenoid content of the leaves decreased in pepper plants under saline conditions, but SNP treatments increased the values. Membrane permeability in NaCl application increased by approximately 304% compared to control application. The SNP treatments increased xylem conduit diameter by 65.7% and epidermis thickness by 61.5% compared to salinity stress. When the results were evaluated, the values closest to the control in many parameters were recorded in the NaCl+SNP 25.0 mu M application and it was found that it was effective in mitigating salinity stress damage. At the same time, 25.0 mu M SNP application improved xylem vessels and cortical cells that may help plants acquire water and minerals more efficiently.