Response of soybean (Glycine max) to physalis (Physalis alkekengi) competition

In order to assess the competitive ability of soybean with P. alkekengi, a test was conducted at sari Agricultural Sciences and Natural Resources University. This research was carried out in two greenhouse and field condition. The treatments consisted of five planting ratios of soybean and P. alkekengi including: 25:75 (soybean - weed), 50:50 (soybean - weed), 75:25 (soybean - weed) and pure (100% soybean and weed species). According to the results the maximum yield of soybean in pot (39.60 g plant-1) and field conditions the maximum yield of soybean (141.44 g m-2) were obtained in weed-free conditions (soybean monoculture) and increasing soybean density reduce P. alkekengi biomass than the monoculture of this weeds. In pot and field conditions, the highest pod number per plant (171.66 and 201, respectively) and 100- seed weight (18.45 and 17.85 g, respectively) were observed in pure soybean (weed-free) cultivation. Also soybean tolerance to different densities of P. alkekengi showed that soybean can tolerate low density (25 percent) of P. alkekengi. Also study the competitiveness index (CI) showed that soybean at low density of physalis was higher and inhibit the weed biomass increment. The results showed that soybeans had a higher tolerance index and competitiveness index than the P. alkekengi. In general, increasing the density of P. alkekengi reduced the yield and yield components of soybeans in both potted and field conditions. In general, soybeans in low densities of P. alkekengi had a higher competitive ability than this species and inhibit the increase of weed biomass.