Responses of Almond Genotypes to Osmotic Stress Induced In Vitro

Drought is one of the major limitations to crop production worldwide. This study was conducted to evaluate the response of five almond genotypes and peach×almond hybrid GF677 to drought stress in vitro, and screening drought tolerance. Explants subjected to polyethylene glycol osmotic stress (0, 3.5, and 7.0% WV) on the MS medium. Increasing PEG level in the medium significantly reduced fresh weight and leaf growth indices of the explants. Concentrations of chlorophylls, anthocyanins and carotenoids were significantly reduced under osmotic stress. Drought sensitive genotypes ‘B-124’, ‘Sepid’, ‘Mamaei’ and ‘Ferragnès’ showed stunted growth with high rate of leaf abscission under osmotic stress. Under osmotic stress, leaf water content, cellular membrane stability and pigments concentration were significantly higher in the leaves of tolerant genotypes ‘Supernova’ and GF677. The results revealed that carotenoids and anthocyanins may be involved in protecting almonds against drought stress. Based on their responses to the osmotic treatments, almond genotypes were divided into drought tolerant (‘Supernova’ and GF677), semi-sensitive (‘B-124’ and ‘Sepid’) and drought sensitive (‘Mamaei’ and ‘Ferragnès’).