Improvement of growth and physiological characteristics and antioxidant enzyme activity under drought stress in almond (Prunus dulcis L.) using selected promising almond genotypes

Abstract

Abstract The scarcity of water is a primary obstacle to the growth and performance of horticultural crops. In this study, the physiological and developmental response of promising almond genotypes under deficit irrigation was investigated. This research was conducted as a factorial experiment consisting of two factors in a completely randomized design with three replications during 2019 and 2020, at the Temperate Fruit Research Center, Horticultural Research Institute. The first factor was almond genotype at ten levels, and the second factor was drought stress at three levels. The results showed that growth (such as plant height, trunk diameter at the top of the plant, length of new branch growth, leaf yellowness) and physiological characteristics such as chlorophyll index based on the SPAD criterion, relative leaf water content, chlorophyll fluorescence and activity of leaf enzymes including SOD, POD, CAT and APX. according to the type of genotype in the conditions of drought stress were different. Among the traits studied, higher proline, RWC and FV/Fm indicated a higher ability to tolerate drought stress in almonds. According to the results of the present study, for instance, drought stress has a significant effect on photochemical efficiency (FV/Fm) of 10 selected almond genotypes. So that, the AH1-99 genotype with 0.585 shows the lowest value and the A-7-100 genotype with 0.751 has the highest value. These results indicate that genotypes, A-7-100, A-100-13, and A-100-8 has more tolerance and adaptation to drought stress than other genotypes respectively. These genotypes are considered for further evaluation to confirm the varieties in order to recommend them for general cultivation in farmer's fields in drought-affected areas. The drought-sensitive genotypes, AH1-99 and A-124-1 were also identified in the present study, which are rich assets to be used as contrasting parents in hybridization programs.