ASSESSMENT OF THE POTENTIALS OF AZOTOBACTER SPP. AS BIOINOCULANTS ON THE GROWTH OF POTTED MAIZE PLANTS

Abstract

The use of chemical fertilizers in crop production has detrimental effects such as soil acidity and eutrophication. There is need for environmentally friendly approach in improving soil nutrients and agricultural productivity. This study aimed at the isolation of Azotobacter spp from the rhizosphere of crops   and the use of these isolates as biofertilizer for the growth of potted maize plants under 5 treatments. These treatments were maize plant only (control), plant with once application of NPK fertilizer, plants with once, weekly and fortnights application of  Azotobacter spp. as bio-inoculants. The counts of Azotobacter obtained from the rhizosphere of the crops ranged from 4.0 × 10⁴ – 1.0 × 10⁶ CFU/g. The three high ranking  in-vitro biological nitrogen fixing and phosphate solubilization isolates  were identified A. chroococcum, A. vinelandii and A. beijerinckii.  At the 7^th weeks of growth, 83.3 and 100% of the plants that received different levels of bio-inoculants had the perimeter of their girths greater than and significantly different from the controls when cultivated in 8.1 and 12.0 litre pots respectively. At least 91.7% of the plants that received bio-inoculants had higher heights than the controls. It is concluded that the application of Azotobacter bio-inoculants enhanced the growth of maize plants compared to the controls.