Effect of biological pretreatment on germination and seedling growth of Cumin (Cuminum cyminum L.) under drought stress

In order to investigate the effect of seed bio-inoculation on some germination indices of Cumin under drought stress a two factors experiment was laid out. Experimental factors included priming in nine levels (bio-priming with 4 strains of PF1, PF2, PF75 and CHA0 of Pseudomonas fluorescent, and 4 strains T29, T36, T39 and T40 of Trichoderma harzianum and non-primed (control)) and three levels of drought stress (0, -3 and -6 bar imposed by PEG 6000). Results showed that by increasing the osmotic potential levels germination indices decreased. At all levels of stress, inoculated seeds had higher germination percentage and root length than non-inoculated seeds. In under stress level of -3 bar, highest germination percentage (86.66%) and seedling weight vigor index (11.93) was obtained from T36 strain that; this treatment was able increase germination by more than 35% than non-inoculated seed. Under -6 bar, the highest (76.68%) and lowest (55%) germination percentage was related to T29 that has no significant difference with T36 (75.83%) and T39 (75.83%) and the lowest amount was related to non-primed treatment (55%). Also at all stress level, the highest length seedling vigor index was related to CHA0 strain. The highest weight seedling vigor index was related to T36 strain (6.4, 5.49 and 4.7 respectively in 0, -3 and -6 abr) and the lowest (4.89) was related to non-inoculated (control) seeds. According to the results, T36 can be suggested as a suitable pretreatment in moderation of the negative effects of osmotic potential on germination of cumin seeds.