Promotion of Seed Germination and Seedling Growth in Zygophyllum atriplicoides using Chemical, Mechanical, and Biological Priming Treatments

Native palatable species are the most important plants for the restoration of arid areas. Zygophyllum atriplicoides is one of the useful species in restoring arid regions, but poor germination and seedling growth are the main problems in the establishment of this species. The objective of this study was to investigate the effect of biological, chemical, and mechanical priming treatments on seedling germination. The experiments were carried out in a completely randomized design with three replications in a laboratory (germinator) and tray culture mid-summer of 2018. Experimental treatments consisted of two chemical treatments including salicylic acid and gibberellic acid at three levels, five biological treatments consist of Azotobacter chroococcum, Azospirillum lipoferum, Bacillus megaterium, Flavobacterium sp. and Pseudomonas fluorescens and mechanical treatments including 24 kHz ultrasonic wave during 5 min. Seed germination and seedling growth traits were measured in different treatments. Analysis of variance showed significant differences between treatments for all traits in both experiments (p<0.01 and p<0.01). The result of the laboratory experiment showed the higher mean values of germination percent (38.33), germination rate (14.69), germination percent day (2.73) and germination index (0.54) in Bacillus treatments than other treatments. Also, Azospirillum increased seed vigor index (56.0), root length (1.33cm), seedling length (2.26cm), fresh weight Root (8.40g), root dry weight (1.20g) and shoot dry weight (1.90g) as compared to control. The maximum shoot length and root to shoot length ratio were obtained by salicylic acid and gibberellic acid 3000 ppm, respectively. Bacillus caused the highest root length (4.73cm), root to shoot ratio (2.20), root (6.50g) and shoot fresh weight (2.63g) and leaf area (11.37). Maximum seedling length and leaf fresh and dry weight were obtained by Pseudomonas fluorescens. According to the results of this study, the use of bacteria, especially Azospirillum, Bacillus and Pseudomonas were effective in better germination of seed.