Natural Occurring Weed's Interference in Melon Quantity and Quality

Weed's behaviors differ in a multiweed-crop competition system compare to a mono weed-crop competition system. The present investigation was carried out in Mashhad, Iran, to study the effect of weeds, which emerged naturally in a multi species community along side with melon, on quantitative and qualitative characteristics of the crop during 2007. Thirty five plots were selected randomly in a girded filed. Weeds were allowed to compete freely with melon by the harvest time in 32 plots. The other 3 plots were weeded during crop development. Weed sampling was conducted prior to melon harvesting. Density, frequency and dry mater were recorded species-wise. Maximum melon plant growth and yield indices were also recorded. Stepwise multivariate regression equations were established to determine the competitive relation between population and dry matter of each weed species and melon characteristics. Results revealed that dry matter had more significant relation with characteristics under study compare to weed density. Weeds showed two adverse competitive responses. According to their effects on melon traits, weeds were divided in antagonistic and synergistic groups. Lesger burdock, redroot amaranth, and black nightshade were antagonistic while fat hen and common porcelains were synergetic. Nut grass had a null effect. Results also showed that yield was more affected by weeds than other melon yield components.