Neem and Gliricidia Hedge Effects on Sweetpotato Production in the Caribbean

Alternatives to the use of agrochemicals in traditional farming practices are needed in order to safeguard the environment of the Caribbean region. Potentially useful plant species for on-farm production of organic inputs include Azadirachta indica A. Juss. (Neem) and Gliricidia sepium(Jacq.) Kunth ex Walp. (Gliricidia). These species are known for pest-repelling and nitrogen-fixing properties, which can result in a decreased use of inorganic pesticides and fertilizers.  Hedges of these species were tested for effects on crop growth and yield of sweetpotato (Ipomoea batatas(L.) Lam.), a potentially important crop for food security in the Caribbean. In this study, the performance of two sweetpotato varieties (Black Vine and Lovers Name) were compared at different distances (1,3,5,7 and 9m) from a 0.5-m tall hedge of alternating Neem and Gliricidia plants. It was conducted without inorganic fertilizer inputs as well as with and without the application of an inorganic pesticide (Actara). Several trends influenced by proximity to the Neem/Gliricidia hedge were: yield, tuber damage, chlorophyll indices and moisture levels.  Yield was reduced by proximity to the hedge for the 'Black Vine' but not for the 'Lovers Name', for which tuberization occurs earlier. The extent of damage caused by white grub with increasing distance from the hedge was higher in both varieties without the use of Actara.  Chlorophyll indices for the 'Lovers Name' increased overall with increased distance from the hedge.  The use of Actara appeared to increase the chlorophyll index for the 'Lovers Name' as distance from the hedge increased.  Soil moisture content was significantly affected by proximity to the hedge- the 'Lovers Name' showing higher percentages of moisture in the soil at 8.1 weeks after planting than the 'Black Vine'.  The use of Actara along with proximity to the hedge also appeared to affect soil moisture, showing a decrease at 14.3 weeks after planting. Yields and damage to tubers were affected by proximity to the hedge with varietal effects and Actara interactions observed for chlorophyll indices and moisture levels. Organic inputs from hedges of Neem and Gliricidia can be beneficial for sweetpotato production in the region.