Phenotypic plasticity of Anacardium occidentale L. seedlings exposed to salt stress based on physiological indicators

Abstract

The study of cashew (Anacardium occidentale L.) response to salt stress from physiological indicators in genotypes contributes to the knowledge of the adaptive mechanisms of this species to stressful conditions. The objective of our research was to analyze the phenotypic plasticity and variation in indicators related to photosynthesis in two genotypes (red and yellow) of Anacardium occidentale L., during the seedling stage under greenhouse conditions. The ef fect of five salinity levels (0.02 dS m-1, 5 dS m-1, 10 dS m-1, 15 dS m-1 and 20 dS m-1) on characters associated with photosynthesis, gas exchange and chlorophyll fluorescence was evaluated. Phenotypic plasticity in response to salt stress was calculated for the indicators evaluated through the phenotypic plasticity index. The red variety showed the greatest ef fects of salt stress on photosynthetic rate, transpiration, sub-stomatal CO2, Fm, Fv, Fv/Fm, Fv/Fo, and Pi abs. The significant dif ferences found in phenotypic plasticity showed higher values in the red variety in most of the indicators evaluated. A negative ef fect of salinity at the seedling stage on indicators related to photosynthesis, gas exchange, and chlorophyll fluorescence was detected, as well as significant dif ferences between genotypes according to the indicators evaluated and the levels of phenotypic plasticity. Photosynthesis and stomatal conductance were the indicators that showed the highest values of phenotypic plasticity.