Improvement of cumin (Cuminum cyminum) seed performance under drought stress by seed coating and biopriming

Cumin (Cuminum cyminum L.) is an annual plant with medicinal properties including numerous stimulus appetites; strengthen the stomach, anti-flatulence, which has low germination, vigor, storage substances, and weak establishment in the soil. In order to improve the physical and physiological properties and investigate the effect of seed coating and biopriming on morphological and biochemical indices of cumin seeds under drought stress a factorial experiment was conducted based on completely randomized design with three replications in the greenhouse at the Department of Agronomy and Plant Breeding, Yasouj University, Iran, in 2017. The experimental factors consisted of six combined levels of seed inoculation (inoculation with strain P.F2, and CHA0 Pseudomonas fluorescence bacteria, T36, T39 Trichoderma harzianum fungi, and without inoculation) with coating, and non-coating without inoculation as a control, and drought stress at three levels (0, -3 and -6 bar). Seed coating performs by 3:1.5:2 ratios of Vermiculite (V), Kaolin (K) and Perlite (P) than seed weight (5 g). Increasing drought stress leads to decreasing of seedling emergence and early vegetative growth of cumin under greenhouse conditions. The results indicated that the highest emergence percentage and rate was obtained from inoculation of coated seed with CHA0 at all osmotic potential conditions. Also, inoculation of coated seed with fungi or bacteria increased the soluble protein and antioxidant enzyme activity of seed. In general, biopriming the coated seed by T36 fungi or CHA0 bacteria improved the cumin seed performance and moderate somewhat the drawback of osmotic stress effects on seed germination and seedling establishment.