Effects of salinity on growth and proline content on bean and alfalfa

Abstract

Soil salinity is a major agricultural constraint in many countries. Plants’ response to salinity depends on the species and the salt concentration in the soil. The objective of this study was to test the resistance of three leguminous plants - common bean (variety ‘El-Jadida’), broad bean (variety ‘Claro de Luna’), and alfalfa (variety ‘Diamon’) - to several salinity rates and to show which one was more resistant to salt stress. This study was carried out under controlled conditions, with six NaCl concentrations (0, 1, 3, 6, and 9 g/kg) added to a mixture of potting soil and sand. A completely randomised design was used, where the three legumes were cultivated with different salt concentrations to determine the effect of these doses on fresh biomass, dry mass, and physiological parameters (sodium and proline content). The results showed the negative effect of salinity on fresh biomass and dry mass of shoots and roots. Claro de Luna, the broad bean variety, was more adapted to salinity than alfalfa and common bean. The amount of sodium in the shoots and roots of the three species increased with increasing salinity. Alfalfa may play a role in soil desalination; at 53.33 mM NaCl, 100 mg alfalfa dry mass absorbed 4.5 mg Na per pot, which corresponded to the uptake of about 0.6 kg Na per hectare of soil. Proline content increased with increasing salt concentrations.