Effect of salt stress on growth, gas exchange attributes and chlorophyll contents of pea (Pisum sativum)

Abstract

Ten pea (Pisum sativum) genotypes (Samarina Zard, Euro, Early Green, Climax, 2001-20, Meteor, Olympia, 9200-1, 9800-5 and PF-400) were used to study the effects of salt stress on the growth, photosynthesis rate, stomatal conductance, transpiration rate and chlorophyll contents. Pea seeds of different genotypes were grown in pots having fine sand as growth medium. After 30 days of germination, the plants were subjected to salt stress under 0, 25, 50 and 75 mM NaCl. At the end of the experiment, the plant growth was significantly decreased with increasing salinity. After one week of salt application, photosynthesis rate, stomatal conductance, transpiration rate, and chlorophyll contents of the plant were remarkably decreased with increasing salinity in all the genotypes. However, the Na ions accumulation was increased with increasing salt stress, which changed the Na:K ratio, and it seems to affect the bioenergetic processes of photosynthesis. Among different cultivars, Climax and 9800-5 were found to be salt tolerant whereas both 2001-20 and Euro showed salinity sensitive behaviour. Tolerant genotypes (Climax and 9800-5) were successful in maintaining high plant dry matter, less concentrations of leaf Na, while high concentration of leaf phosphorus and potassium contents under the saline environment. Key words: Pea, photosynthesis, stomatal conductance, transpiration, chlorophyll.