Growth and ion accumulation in dwarf cashew plants at different times of salinity exposure

Abstract

This work aimed to evaluate the influence of salt stress exposition on growth and ion accumulation in dwarf cashew plants. For this purpose, cashew nuts (CCP 06 clone) were sown in plastic trays containing vermiculite moistened with nutrient solution containing NaCl with electrical conductivities ranging from 0.0 to 18.0 dS m-1. Plants were harvested after 30 and 60 days under salt stress. It was determined the shoot dry masses (SDM) and root (RDM), the SDM/RDM ratio, Na+, K+, Cl- and NO3 - contents and the Na+ and Cl- fluxes for whole plant in the period between two times of exposure to salt stress. The cashew growth was affected by salinity and by the exposure time to this stress, and the plants subjected to 60 days of stress were the most affected by NaCl. The Na+ and Cl- contents increased in all plant tissues, while the NO3 - content was reduced and K+ content has not changed by salinity. The Na+ and Cl-fluxes increased with salinity; however Cl- seemed to be more harmful to plants, since this ion has been absorbed in a higher ratio than Na+. The growth reduction in dwarf cashew is intensified when exposure to salt stress is longer and it is more associated with uptake and excessive accumulation of Cl- than Na+.