Abstract:

Drought stress at the germination and seedling stages is a key factor in reducing crop yields in arid and semi−arid areas. Seeded surrounding microenvironment regulation is one of the important technical measures to improve crop drought resistance. In this paper, wheat (Jimai 22) was selected as the experimental variety, while Bacillus subtilis ACCC 19742 and Bacillus magaterium ACCC 04296 were chosen as the experimental strains. The bacteria were encapsulated using microencapsulation. Wheat seeds coated with bacterial microcapsulation were investigated for seed germination and seedling growth under drought stress. Four treatments were established: Bacillus subtilis coatied (M), Bacillus megaterium coatied (B), Bacillus subtilis and Bacillus megaterium compound coatied (MB), and uncoated treatment (CK). The results showed that the compound bacterial coating had the best effect than the single-strain coatings. The ratio of emergency, above ground dry weight and root-shoot ratio were significantly improved, increased by 12.8 percentage points, 17.8% and 5.3% compared with M treatment, while 15.3 percentage points, 14.7% and 5.7% compared with B treatment. Compared with CK treatment, ratio of emergency was increased by 25.9 percentage points, above ground dry weight increased by 21.8%, root-shoot ratio increased by 9.8%, and total root length, surface area and total volume increased by 37.5%, 34.7% and 84.3% respectively. The activity of superoxide dismutase (SOD), peroxidase (POD), catalase from micrococcus lysodeikticus (CAT) significantly increased, and the content of malondialdehyde (MDA) decreased, but the content of proline (PRO) obviously increased. Fluorescence parameters F_v/F_m and ΦPSⅡ were both larger than that of CK treatment, which showed that coating with composite bacteria could improve the drought resistance significantly. In summary, seed coatied with bacterial microencapsulation can promote seed emergence, root growth, and stress-tolerant enzyme activity in drought stress conditions to increase drought tolerance. Moreover, a compound microbial coating is the optimal method.

Key words: Wheat, Microbial seed coatings, Bacillus subtilis, Bacillus megamegavis, Enzyme