Investigation of Marigold Interference Effect on Weed Composition and Diversity of Tomato in an Intercropping System

In order to investigate the role of marigold (Tagetes erecta) interference effects on weed composition and diversity of tomato (Solanum lycopersicum), an experiment was conducted as split plot based on complete randomized block design with 3 replications at Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during 2010 to2011. Treatments included three tomato varieties (Jina, Flat and strain hitack Tork) and five cropping patterns (tomato monoculture and marigold- tomato intercropping with 1:1, 1:2, 1:3 and 1:4 ratio). Results indicated that in the first sampling, the highest weed density was observed in tomato monoculture (78.96 plants per m2). The lowest weed density was obtained in marigold and tomato intercropping with 1:3 ratio (37.62). In the second sampling, the lowest weed density was in marigold and tomato intercropping with 1:3 ratio. In the first sampling, total dry weight of weed was more than that in the second sampling. In two sampling, the highest total dry weight of weed was observed in the marigold and tomato intercropping with 1:3 ratio. By altering the cropping pattern, Shannon, Margalof and Simpson diversity indices of weed were changed. The lowest weed diversity indices were observed in the marigold and tomato intercropping with 1:1 ratio. Also, significant positive regressions were obtained between insect diversity indices (Shannon, Margalof and Simpson) and weed diversity indices.