Studies on the influence of foliar application of chemicals on the microflora and certain enzyme activities in the rhizosphere of Eleusine coracana Gaertn

Abstract

The studies on the activities of the enzymes hydrolysing sucrose and starch in the rhizosphere of finger millet plant (Eleusine coracana Gaertn.) showed significantly greater activity of both the enzymes in the rhizosphere than in the soil away from the influence of plant roots. The activity of the enzyme hydrolysing sucrose was always greater than that hydrolysing starch and a constant ratio in the activity of these two enzyme systems was maintained all through plant growth. A highly positive correlation between the bacterial and fungal populations of the rhizosphere and the enzyme activities was also observed. Foliar application of N as ammonium sulphate, P as disodium phosphate and K as potassium chloride, seemed to increase the activities of the enzymes in the rhizosphere from the 45th to 75th day of plant growth, such an effect being relatively more with K than N or P. Application of Dimecron 100, a systemic insecticide and Blastin, a systemic fungicide, on the foliage significantly altered the populations of bacteria and fungi as well as the enzyme activities at various stages of plant growth. Although the enzyme activities were reduced initially due to the first spray treatment, a subsequent significant increase in the enzyme activities was recorded. The increase in the enzyme activities due to the foliar treatments appeared to have been retained in the rhizosphere even 15 days after the last spray.