The Evaluation of Intercropping System of Indigo (Indigofera tinctoria L.) and Roselle (Hibiscus sabdariffa L.) on Yield, Weed Biodiversity and Changes of Weeds Community

Application of intercropping systems is one of the ecological methods for controlling weeds due to maximization of soil cover and plant diversity. In order to study the effect of intercropping system of indigo (Indigofera tinctoria L.) and roselle (Hibiscus sabdariffa L.) on biodiversity, weeds population changes and plant yield an experiment was conducted based on randomized complete block design with three replications in the Research Farm of South Kerman Agricultural and Natural Resources Research and Education Center, Jiroft, Iran, during 2014-2015 growing season. Treatments were additive and replacement series of intercropping including: I100:H100, I100:H50, I50:H100, I50:H50 and monoculture of indigo and roselle. The results showed that the density and biomass of Amaranth, Cyprus and other weeds (Heliotropium europaeum L., Heliotropium europaeum L. and Portulaca oleracea L.) were significant by intercropping of indigo and roselle. Amaranth weed density in I100:H100, I50:H100 and I100:H50 were 57.44, 81.5 and 70.38%, respectively, lower than roselle monoculture. The highest of Cyprus weed density was in indigo and roselle monoculture and I50:H50 intercropping ratio. The density of other weeds in I50:H50, I50:H100, I100:H50 and I100:H100 ratio were 44.4, 48.2, 51.8 and 77.7 % lower than monoculture. Weed biomass in I100:H100, I10:H50 and I50:H100 ratio were decreased by 25.44, 23.38 and 15.98 % in comparison to monoculture, respectively. The highest yield of roselle (1114.2 kg/ha) and leaf dry weight (3016.7 kg/ha) of indigo was observed in I100: H100 ratio. The values of the land equivalent ratio (LER) in all of intercropping treatments were greater than unit and the highest LER belonged to H100: I100 treatment, indicating that intercropping system outperforms the monoculture in terms of crop productivity and hence weed control.