Antioxidant Responses and Germination Indices of Five Tropical Alfalfa Varieties under Drought Stress (Different Concentration of Polyethylene Glycol)

BACKGROUND: Abiotic stresses are considered factors that decrease the crop yield and can lead to a significant decrease in the production of main agricultural products on average. OBJECTIVES: One of the main approaches to obtaining drought tolerance data involves selecting relevant statistics based on the biochemical traits and germination indices. METHODS: Current research was carried out according factorial experiment based on completely randomized design with three replications, on five tropical Alfalfa varieties during germination phase with two factors in September 2017. The first factor was drought stress, applied using various concentrations of polyethylene glycol (PEG) with four osmotic potential levels of 0, -2, -4, and -6 bars. The second factor was variety, which included five Alfalfa cultivars; Baghdadi, Nikshahri, Yazdi, Omid (synthetic Alfalfa), and Mesasirsa. RESULT: Levels of drought stress had a significant effect (at the 1% level) on mean time to germination (MTG), coefficient of velocity of germination (CVG), mean daily germination (MDG), and final germination percentage. The effect of genotype was significant (at the 1% level) for all traits and germination indices, except MTG and CVG. The interaction effect of drought stress and variety was significantly different (at the 1% level) for the amount of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase activities (GPX) activity. A mean comparison of indices and antioxidant activities showed that Baghdadi and Yazdi varieties, owing to their high final germination percentage (63.75% and 59.67 %, respectively) and higher antioxidant activity, were classified into a more favourable statistical group (group A). CONCLUSION: This study on Alfalfa varieties found that Baghdadi, Nikshahri, and Yazdi perform well under water stress, showing high germination rates and adaptability to irregular rainfall. Notably, the Yazdi variety is particularly suitable for breeding programs aimed at enhancing drought tolerance in Alfalfa.