Study on seed germination traits of Agropyron desertorum and Agropyron pectiniform with ascorbic acid pre-treatment under drought stress

The aim of this study was to evaluate the seed germination characteristics of A. desertorum and A. Pectiniforme primed with ascorbic acid under drought stress on laboratory conditions in germinator. Environmental stress, particularly drought stress, are the factors inhibiting growth and development of plants. Lack of water in germination stage depends on the severity and duration of stress leads to lack of germination. The present study was conducted to two important species of A. desertorum and A. Pectiniforme rangelands, which are the most valuable forage species for rangeland regeneration. Drought stress induced by polyethylene glycol at four levels (Zero, -4, -8 and -16 bar) and priming with ascorbic acid at four levels (Zero, 0.3, 0.5 and 0.8 mM) for 24 hours in four replicates and 50 seeds per replicate. The results showed that the most studied traits (germination percentage and speed, radicle length, plumule length and vigor index) in both species, except the mean germination time, significantly decreased with increasing ascorbic acid concentration and drought stress. Tolerance threshold in species A. Pectiniforme at 0 mM (control) priming in zero and 4 bar drought stress had the highest percentage of germination, vigor index and germination value, that there was no significant difference between the two levels of drought stress. In general, it can be concluded that tolerance threshold of A. Pectiniforme to drought was -4 bar and had more tolerant to drought stress than A. desertroum