Description

Abstract: Tree-crop interactions in agroforestry systems involving vegetable crops have not been studied extensively, for previous research in agroforestry focused on agronomic arable field crops. A vegetable agroforestry system was established at the World Vegetable Center (AVRDC) to study tree-crop interactions in alley cropping vegetables with tropical fruit trees in terms of competition and/or complementarity; to investigate the influence of tree crops on natural habitat and insect pest population in vegetable alley cropping systems; and to evaluate total productivity and economic return from high-value horticultural crops in an agroforestry system. In December 2005, seedlings of 12 tropical fruit tree species were planted: Anona reticulata, Artocarpus heterohyllus, Chrysophyllum caimito, Coffea arabica, Eugenia brasiliensis, Eugenia uniflora, Pouteria caimito, Pouteria campechiana, Psydium littorale, Rollinia mucosa, Syzygium samarangense and Tamarindus indica. The trees were on raised beds 50 cm high and 1 m wide with hedgerow spacing of 8.0 m. Tree spacing within beds varied from 1.5 to 3.0 m. Vegetable crops were sequentially grown in alley beds between tree hedgerows starting in October 2006, 10 months after tree establishment, until April 2007. Three sources of organic fertilizer (compost) were compared and evaluated for effects on growth and yield of vegetable crops. The trial used a randomized complete block design with four replications.

Establishment and initial growth of trees varied according to species. Outstanding species were A. heterophyllus, C. caimito, T. indicus and A. reticulata. All vegetable crops produced average yields with minimum competition from tree crops. Yield response of vegetable species to compost application varied significantly with planting season. Tree-crop competition for water, nutrients, and light was insignificant as observed during early establishment. Results suggest that integration of high-value vegetable crops can provide quick economic returns in agroforestry systems.