و سرزني ذرت بر عملكرد، اجزاي عملكرد، رقابت و اكولوژي توليد در كشت مخلوط )GLYCINE MAYL.( و سويا )ZEA MAYS L.( تاثير تراكم كاشت ذرت

Effects of Plant density and topping on yield, yield components and competition of Corn and soybean grown in mixture

The yield advantage and interspecific competion were studied in corn-soybean mixtures. Species monocultures and all combinations of 3 corn densities (5.5, 7.5 and 9.5 plant/m2) and 3 soybean densities (23, 33 and 43 plant/m^2) were plantes in a complete randomized block design with factorial arrangement and 3 replicates. Topping treatment on corn was conducted at soft dough stage and data analysed as a split plot design where topping were allocated to main plots. Ignoring the soybean density, increase in corn density to 9.5 plant/m2 led to an increased corn grain yield in mixture. The highest grain and biological yield of soybean was obtained in mixture with medium corn and low soybean densities (7.5 and 23 plant/m2, respectively). Corn topping led to a increase in corn grain no.per row and 500 grain weight of sobyean. However, the other yield components of species were not significantly affected by this treatment. Reciprocal yield models showed that in corn interaspecific competition and in soybean interspecific competition were the main determinats of grain and biological yield. That is corn was the dominant species of mixture. When corn topping was conducted the effect of each corn plant on grain and biological yield of soybean was respectively, equivalent to 9.37 and 9.14 soybean plant. However, this equivalency in control treatment was increased to 11 and 13 soybean plant, respectively. That is, corn competitive ability decreased after topping. This result was confirmed according to competiotion indices. Land Equivalent Ratio (LER) of mixtures increased with increasing spices density in mixture. Corn topping was also led to an increase in LER so that the highest LER in topping and non-topping treatments were 1.215 and 1.078, respectively.