ISOLATION AND CHARACTERIZATION OF POTENTIAL BIOCONTEROL RHIZOSPHERIC BACTERIA EFFECTIVE AGAINST WHITE ROT (SCLEROTIUM CEPIVORUM BERK) AFFECTING GARLIC (ALLIUM SATIVUM L.) UNDER LABORATORY CONDITIONS

Garlic (Allium sativum L.) is the second most widely used Allium used as food, medicinal, condiment and cash crop vegetable. Its productivity and yield is affected by both abiotic and biotic factors. One of the biotic agents that aggressively attack garlic is white rot (Sclerotium cepivorum). The main aim of this study was to isolate and screen potential antagonists for controlling this pathogen. Consequently, 23 rhizospheric bacterial isolates were screened. The isolates’ biocontrol potential against the pathogen was tested under both laboratory and greenhouse conditions using microbiological procedures. Among these isolates, 11 (47.8%) of them inhibited the radial growth of the pathogen with growth inhibition zone ranging 60 - 88%. The isolates also showed wide morphological and cultural diversity. Nine (82.8%) of the isolates solubilized phosphate at a solubilization index ranging from 2.3-3.72 cm. Among the isolates 6(54. 6%), 10(90.9%), 5 (45.5%), 100% and 5 (45.5%) were chitinase, cellulase, protease, ammonia and cyanide producers, respectively. Of the biocontrol traits tested, 6 (54.55%) of them were endowed with all the expected biocontrolling characteristics. Most of the isolates showed high resistance to extreme environmental stresses including pH, temperature and salt concentrations. Moreover, the isolates also showed high tolerance to the tested antibiotics and heavy metals. In the all the tested parameters conducted under laboratory conditions, isolates WUGR-8, WUGR-14 and AAUGPR- 92 showed the top performance. Consequently, these isolates can be recommended as candidate microbial inoculants for greenhouse applications