The effects of biotic interaction between tomato and companion plants on yield

Tomato plants are mainly cultivated as monocrops in Brazil by intensive using of chemical products. Aiming to contribute for the reduction of the use of pesticides and enhancing biodiversity on plantation area, we conducted field experiments with tomato plants intercropped with aromatic herbs, in Sergipe state, Brazil, to evaluate the performance of tomato plants grown in monocrop and in two intercrop designs: replacement series and additive designs. The herbs used were basil (Ocimum basilicum), rue (Ruta graveolens), fennel (Foeniculum vulgare) and peppermint (Mentha piperita). Two experiments were carried out under an organic management system and they were designed in a complete randomized blocks design with four replicates. Total height, canopy area, production, yield and land equivalent ratio (LER) were determined. Herbs used different competitive strategies in interactions. Tomato plants had lower yield in intercrop with fennel than using other intercrops. A reduction was observed on tomato yield: from 20.4 t ha-1, in monocrop, to 13.1 t ha-1 in intercrop. Fennel plants had higher height and canopy area than other intercrops used and it caused shadow on tomato plants. However, it was noted that tomato plants had lower percentage of yield loss caused by tomato fruitworm (24%) in intercrop with fennel than others. The tomato relative yield was larger in intercrop with rue (13.6 t ha-1) and lower in intercrop with fennel (6.4 t ha-1). The rue plants supported a significant increase on commercial yield of tomato fruits (about 26%). The greatest losses by tomato fruitworm damage occurred in monocrop and in intercrop with peppermint. The results show the interaction between tomato and rue plants was advantageous for tomato yields. Among herbs, basil had higher yield (96.5 t ha-1) than others. LER results reveal that all intercrops studied allowed for improving use of land.