Growth and physiological aspects of bell pepper (Capsicum annuum) under saline stress and exogenous application of proline

This study aimed to evaluate growth and physiological aspects of ‘All Big’ bell pepper, under saline stress and exogenous application of proline on the leaves. The research was conducted in pots adapted as drainage lysimeters under greenhouse conditions, using sandy-loam eutrophic Regolithic Neosol, in the municipality of Campina Grande-PB, Brazil. The experiment was set in randomized blocks, in order to test two levels of irrigation water electrical conductivity - ECw (0.6 and 3.0 dS m-1) associated with four proline concentrations (0, 10, 20 and 30 mmol L-1). Plants were grown in 10-L pots for 50 days after transplantation. This period corresponds to the transition of vegetative and reproductive stages, in which plants were evaluated for growth, gas exchanges and chlorophyll a fluorescence. The increase in irrigation water salinity reduced growth, gas exchanges and the efficiency of photosystem II in bell pepper plants. Proline concentrations from 12.8 to 16.8 mmol L-1 incremented the activity of gas exchanges, reducing the effect of saline stress on bell pepper plants. Proline concentrations under study did not influence chlorophyll a fluorescence of ‘All Big’ bell pepper plants.Key words: Saline water, gas exchanges, chlorophyll a fluorescence, proline