Evaluation of salt tolerance of Pepper plant (Capsicum annuum L., cv. Jalapino) cultivated in greenhouse

Abstract

Soil salinization is an increasing problem for many areas throughout the world especially in arid and semi-arid regions which reduces vegetables and crop production in general. The variability of crop salt tolerance under different environmental conditions requires species-specific and environment-specific field evaluations of salt tolerance. In this study, Pepper (Capsicum annuum L., cv. Jalapino) plants were grown in greenhouse under six different irrigation treatments: a nonsalinized control (EC = 0.11 ds m^-1) and five concentrations of diluted sea water, corresponding to EC of 2.0, 4.0, 6.0, 8.0 and 10.0 ds m^-1 in order to evaluate plant development as well as leaves and fruit content of some compounds related to salinity stress. Irrigation water with an EC of 2 ds m^-1 or more resulted in progressive reduction in all parameters tested (plant height, branches number, leaves number, nodes number, node length, flowers number, fruit number, fruit length, fruit diameter, and fruit weight). For instance, increasing the electrical conductivity of the irrigation water to 2.0 ds m^-1 caused reduction of (8%, 34%, 12%, 6%, 13%, 18%, 37%, 11%, 6%, 24%) of parameters tested, respectively. While increasing the electrical conductivity of the irrigation water to 6 ds m^-1 caused reduction of (42%, 67%, 47%, 43%, 22%, 56%, 68%, 42%, 19%, 50%) of parameters tested, respectively, compared to control. The regulation of ascorbic acid content in leaves or fruit and chlorophyll content in leaves was most likely functionally associated with modifications of the plant, for instance, irrigation with 2 ds m^-1 caused reduction of ascorbic content of 12% in leaves and 8% in fruit, and reduction of chlorophyll content of leaves of 21%, compared to control. While increasing the electrical conductivity of the irrigation water to 6 ds m^-1 caused a reduction of ascorbic content to 23% in leaves and 26% in fruit, and reduce chlorophyll content in leaves to 24% compared to control. Irrigation water with 8 and 10 ds·m^-1 highly affected all parameters tested specially fruit number where no fruit was obtained, at the same time flower number was highly diminished to 4% compared to control.

Keywords: Pepper (Capsicum annuum L, cv Jalapino), salinity stress, Chlorophyll, Ascorbic aci