Effectiveness of the entropy weight method to evaluate abiotic stress tolerance in citrus rootstocks

Aim of study: The entropy weight method (EWM) is considered one of the most reliable and scientific approaches when decision making is influenced by multiple factors. However, there are no reports on the application of EWM in the evaluation of abiotic and biotic stress tolerance in crops. In this study, abiotic stress via saline water irrigations was imposed on different citrus rootstocks. The relative stress tolerance levels of rootstocks were ascertained using EWM and compared with standard fuzzy membership approach and the factor analysis. Area of study: Punjab Agricultural University Regional Research Station Abohar, India, 2017-2019. Material and methods: In a pot culture study, about 11/2 yr-old rootstock seedlings were exposed to saline water irrigations with 4 and 6 dS m(-1) electrical conductivity (EC) for 60 days. Saline water response index for mineral composition of plant parts, physiological and biochemical attributes of rootstocks were calculated for each salinity level over 2 dS m(-1) conductivity water, considered as control and subjected to further analysis. Main results: At 4 EC, the entropy weight and membership function value of the rootstocks ranged 0.758-0.998 and 0.682-0.731, respectively. The corresponding values at 6 EC ranged between 0.759-0.991 and 0.391-0.728, respectively. Following EWM, the rootstocks were rated for their relative tolerance levels as: Rangpur Lime>Cleopatra>Volkamer Lemon=Rough Lemon>Carrizo at 4 EC salinity level. At 6 EC, the order was: Cleopatra>Rangpur Lime>Volkamer Lemon>Rough Lemon>Carrizo. The results were consistent between EWM and standard principle component analysis approaches. Research highlights: The study suggests that the comprehensive evaluation of crop genotypes for abiotic stress tolerance is also feasible with the EWM.