VESICULAR ARBUSCULAR MYCORRHIZA IN AGRO-FORESTRY SYSTEMS OF COFFEE, CACAO AND PEPPER

Abstract

Kandyan forest gardens are typical examples of mixed cropping systems of Sri Lanka. These areconsidered as the older agro-forestry systems. They contain a wide range of perennial cropspecies, which survive mostly without inorganic fertilizer. The Delpitiya Mixed Cropping Model(DELMIX) was planted in 1978 by using eroded tea land. DELMIX receives all therecommended inputs and cultural practices such as fertilizing, weeding, training and pruning.This study was conducted in the above agro-forestry systems to estimate the mycorrhizalpopulation of coffee, cacao, pepper and to determine the effects and association of mycorrhizaon these plant species

Vesicular arbuscular mycorrhizae (\~) were found to be associated with vigorously growingcoffee, cacao, and pepper plants in he unfertilized agro-forestry systems. Artificially inoculatedcoffee and cacao seedlings had a significantly higher growth rate than that of uninoculatedseedlings. Inoculation of VAM in pepper nursery was found to enhance growth and producehealthy cuttings. There was no significant difference between the growth of artificiallyinoculated coffee plants grown in the field with application of fertilizer. Unhealthy stunted plantswere observed in the uninoculated coffee grown without application of fertilizer.

were observed in the uninoculated coffee grown without application of fertilizer.The population of VAM spores was compared in the rhizosphere of coffee, cacao and pepper inthe DELMIX and other agro-forestry systems. These results indicated that unfertilized agroforestrysystems contain significantly higher number ofVAM spores. Hence, it can be concludedthat VAM association had a better beneficial impact in the agro-forestry systems of coffee, cacaoand pepper.