The Effect of Plant Growth Promoting Rhizobacteria (PGPR) on Germination and Seedling Growth of Sorghum bicolor L. Moench

Abstract

Germination is the first important step of the plant growth in the land. The germination and growth of sorghum in marginal land can be optimized by inoculating with PGPR (inoculants), hydrogel and CMC (carriers). The aim of the research was to evaluate the response of germination and seedling growth of sorghum using PGPR inoculation with hydrogel and CMC as carriers (in vitro) and pots containing sterile sand (in vivo). The experiment used PGPR (Azospirillum lipoferum 1103D, Azotobacter chroococcum 4103D, and Bacillus sp. 3D), and hydrogels as the reserve water, as well as carboxymethyl cellulose (CMC) as the adhesive media. The results showed that the combination of PGPR-mix (Azospirillum, Azotobacter, Bacillus) with hydrogels as bio-organic fertilizer and CMC as carriers has promoted the growth of the roots, shoots and vigour index of in vitro sorghum germination, as well as increased the root length, shoot length and total dry weight of sorghum seedlings in pots containing sterile sand. The best result of in vitro experiment (root length = 8.67 cm; shoot length = 12.6 cm; and vigor index = 2127.00) was obtained by sorghum seed inoculated with single PGPR inoculant (A. lipoferum) with carrier of CMC. The root length, shoot length and total dry weight of the highest sorghum seedlings were obtained by PGPR-mix inoculants without carriers (46.5 cm, 12 cm, and 0.477 g), PGPR-mix with carrier of CMC (48.67 cm, 15.67 cm, and 0.431 g), and PGPR-mix with carrier of hydrogel (48.67 cm, 15 cm, and 0.430 g).