EFFECT OF COVER CROPS ON WEED DENSITY AND WEED BIOMASS IN TOMATO

Cover crops are an effective tool in the nonchemical weed management in sustainable agriculture. In order to evaluate the effect of type and time planting of cover crops on weed control in tomato, a factorial experiment was established using a randomized complete block design with three replications at 2013 on personal farm located about 65 kilometers from Shiraz province. The factors were included the type of cover crop at four levels (rye, red clover, rapeseed and control (no mulch)) and time of planting in three levels (one month before tomato transplanting, at the same time and one month after transplanting).The results showed that the type and time of planting of cover crops had a significant effect on the weed density and weed dry weight and tomato yield. Planting cover crops decreased weed density up to 35% and the weed dry weight of 67% compared with control. Also, cover crops reduced density of Convolvulus arvensis, Portulaca oleraceae and Echinochloa crus-galli as 8, 4 and 6 times compared with control. Tomato yield increased 60/42% with cover crop. The results showed that cover crops are appropriate tool for weed management in sustainable agricultural systems and can be used in integrated weed management.