Abstract
Allelopathy refers to the process involving secondary metabolites of plants, microorganisms, viruses and fungi enhancing the development and growth of biological and agricultural systems. Five experimental plots were used and each individual plot was 10×10m and consisted of 5 pairs of Papaya plants spaced with 5 feet. For the first, second, third and fourth experimental plots, the Papaya plants intercropped with 2 rows, 3 rows, 4 rows and 5 rows of marigold seedlings respectively, at one foot/30cm distance within the row and between the rows. The fifth plot was considered as the control without marigold. The study ended 65 days after intercropping of Tagetes erecta. Soil samples were collected from all plots for microbial and nematode analyses before and after intercropping of Tagetes erecta in the experimental plots. T4 sample with 5 rows of T.erecta intercropped plants alone exhibited single gall. M. incognita population of J2 individuals got reduced to 87.5% in T1, 58% in T2, 47% in T3 and 33% in T4. Gall index did not decimate immediately. The population density of papaya parasitic nematode gradually decimated and was gradually increasing of beneficial bacteria while increasing the number of intercropping of T.erecta. Though T4 which had 5pairs of papaya plants intercropped with 5 rows of T.erecta showed higher reduction in nematode population it is not economical. Hence T2 which had 5pairs of papaya plants intercropped with 3 rows of T.erecta is advised to practice for the best and economical one.
