Author : Maria Viva Rini

Summary : A pot experiment was conducted to study the effectiveness of two vesicular-arbuscalore mycorrhiza (VAM) species in enhancing growth of cocoa seedlings. Cocoa seedlings of hybrid UIT1xNa32 inoculated with Glomus mosseae and Scutellospora calospora either as a single inoculum or as mixed inoculum and uninoculated control were grown in 2 kg sterilized Tai Tak series soil. The study used a single factor experiment arranged in a completely ramdomized design, with the type of inoculum as a factor with four applications. The experience was conducted in greenhouse No.11C of Universiti Pertanian Malaysia. Of the four treatments used, plants inoculated with mixed inoculum gave more pronounced and significant vegetative growth (as measured by plant height, total leaf area, root dry weight, and nutrient content in leaf tissue) compared to the other treatments. The effect of mixed inoculum G. mosseae and S. calospora was further evaluated in the field using a split-plot design, with VAM treatment as the main plot and cocoa clone as the subplot. Five selected cocoa clones (KKM3, KKM4, KKM5, PBC137, and PBC 178) were grafted onto nine year old cocoa trees from hybrid UITIxNa32. Data were collected at three, five, and seven months after VAM inoculation. Inoculated clones showed better and significant plant growth, with longer scion lengths and larger leaf area index than the inoculated ones. Crop physiology was also significantly affected by VAM, with higher relative water and chlorophyll content in the leaf and lower stomatal resistance. Results obtained also indicated that the mixed inoculum significantly improved VAM development in the soil, subsequently enhancing phosphorus, potassium, and magnesium uptake by the plants. This subsequently shortened the PBC clones' vegetative phase, enabling them to flower earlier. Between the two clones tested, the PBC clones especially PBC 137, prove to be move superior than the KKM clones. Soil physical properties such as soil moisture, percent aggregate and aggregate, stability...