The effect of Azotobacter inoculation on shallot plants (Allium cepa) and availability of phosphate in the saline soil

The impact of Azotobacter inoculation on shallot plants (Allium cepa) and available phosphate insaline soil. Biodiversita 18: 86-94. Azotobacter is diazotroph bacteria having character as Plant Growth Promoting Rhizobacteria(PGPR). It provides growth hormones such as IAA, ACC-deaminase, N and P nutrients. This objective of this study was to determinethe effect of Azotobacter inoculation on the growth and yield of shallot crops and available P in saline soil. The experimental design wasa completely randomized design with factorial pattern. The first factor was the source of water, freshwater and sea water. The secondfactor was the source of inoculants: (i). No inoculant (control), (ii). NPK fertilizer, (iii). Azotobacter paspali, (iv). Azotobacterchroococcum, (v). Azotobacter spp.1, (vi). Azotobacter spp.2, and (vii). Mixed Azotobacter inoculants. All treatments were repeatedfour times. The results showed that inoculation with mixed Azotobacter (#7) consisted of Azotobacter paspali, Azotobacterchroococcum, Azotobacter spp.1, and Azotobacter spp.2, caused better growth and yield of shallot crops compared to single Azotobacterin saline soil. Inoculation of Azotobacter chroococcum on “Tuk Tuk” cultivar shallot reduced plant sensitivity to salinity up to 4.19dS/m, improved the growth and shallot bulbs (101.28 g/pot). The Azotobacter maintained its population up to 106 cfu/g of soil duringPMEase activity at 0.170 μg/mL p-nitrophenol hour and available phosphate at 0.898 ppm until post-harvest. The highest activity ofPMEase and available P in soil during flowering and post-harvest was obtained from the treatment of mixed Azotobacter at populationdensity of 106 cfu/g of soil.Keywords: Azotobacter, shallot, salinity, available P, PMEase BIODIVERSITAS ISSN: 1412-033X Volume 18, Number 1, January 2017 Pages: 86-94