ROOT COLONIZATION AND PERSISTENCE· OF Purpureocillium lilacinum IN RBIZOSPHERE AS INFLUENCED BY SOME CROP SPECIES AND Meloidogyne incognita

Abstract

The 'effect of ten crop species along with two different rooting media viz" coco dust and soil on the root colonization ability of the fungal BCA Purpureocillium lilacinum and its persistence in rhizosphere of the ten crop species along with the presence or absence of nematode were evaluated through a test tube experiment in laboratory and, a pot experiment in shade house. P. lilacinum resulted, in root colonization in all of the crop species in varying percentage depending on the rooting media and the crop species themselves. A constant 100% and an average of 45.30% root colonization were obtained in coco dust and in soil, respectively. In soil, a maximum and a minimum root colonization was observed in cucumber (67.17%) and chickpea (30.55%), respectively; whereas maize (55.50%), potato (50%), brinjal (48.14%), cabbage (44.28%), rice (44.26%) and tomato (43.45%); wheat (37%), soybean (32.07%) gave statistically similar result to cucumber and chickpea, respectively. Population dynamics of the fungus showed no significant difference between soil without crop species and soil from the root zone of majority of the test crop species. Overall, 8 out of 10 crop species showed higher densities compared to soil. Of them, 3 (maize, brinjal, soybean) showed significantly higher CFU/g of soil whereas the-rest 5 (rice; wheat, potato; cucumber, chickpea) showed insignificantly higher CFU/g of soil and conversely, 2 (tomato and cabbage) showed significantly lower CFU/g of-soil in the rhizospbere compared to soil. Both the crop species (in most cases) and the nematode population did not exert significant effect whereas time was the factor to have an obvious effect on the population densities of P. lilacinum. The reduction in CFU/g of soil compared to initial densities ranged from 6.5% in brinjal to 14.'6% in cabbage, 9.8% in brinjal to 21.8% in cabbage, and 17.3% in maize to 32% intomato at 10, 20 and 30 DAI.