Development of farming systems models integrating Jatropha curcas in various production systems: component 4.3: Development of farming systems models integrating Jatropha curcas in various agricultural systems

Based on ocular observation of the results, jatropha can be integrated with agricultural crops. Sweet potato can yield as high as 14 t/ha as intercrop with jatropha. Other crops like arrowroot, turmeric showed good standing but the yield performance remains to be seen. Papaya may not be a good intercrop with jatropha as it has common pest with jatropha. The distance of planting of jatropha that will give high income still remains to be determined. Statistical analysis of the initial data showed no significant difference on the growth of the jatropha under different configuration. Likewise, the distance of planting of coconut can be modified to allow the planting of upland crops including jatropha, the distance of planting that give high income still have to be determined. Majority of data on microbial density comparisons and presence of root colonization indicates that Jatropha curcas is not detrimental to most of the microorganisms examined. In fact some results even exhibited a higher number of bacteria, other functional groups and fungi in Jatropha planted soil than in control. It even stimulates VAM [vesicular arbuscular mycorrhizae] fungi sporulation and root colonization under field conditions. This suggests the lack of fungicidal compounds that adversely affect fungal densities in soil. Ability of J. curcas to survive in poor conditions and at the same time promote mycorrhizal proliferation and other beneficial microbes in soil are characteristics that could be given consideration with regards crop rotations, inter-cropping methods or land restoration. The Jatropha plantations examined, however,are still in their early or infancy stage and their adverse effect could not be established yet. A follow-ups monitoring activities of the population and diversity changes must be done for at least five years under Jatropha plantations. In the further investigation of possible fungicidal and bacterial compounds from Jatropha curcas, the researchers propose studies under green house or laboratory conditions. Extracts from the different parts of the plant (leaf, seeds, roots, or bark) could be tested for antimicrobial activities. In field studies, it would be more beneficial if population density of soil could be monitored over a period of time. This would give a trend and better view on the effects Jatropha curcas has on VAM spore density of soil. The researchers also propose the use of MPN [most probable numbers] method to measure the total infective propagules of VAM fungi. This would account not only spore but also hyphal propagules, both used to form mycorrhiza. Aside from measuring infective propagules, biodiversity of the fungi in Jatropha curcas plantations is also worth studying as it may provide insight on the effects that large scale Jatropha curcas plantations may have on the diversity of VAM fungi. Also, it would be preferable if microbial densities could be monitored periodically in order to obtain information based on their changes rather than on comparisons.