Effect of replacement and additive intercropping on the yield of maize (Zea mays L.) and potatoes (Solanuum tuberosum L.) in the region of Nikshahr

  Increasing agricultural production to match increasing demand of food sources is inevitable (FAO, 2006). It causes too much pressure on the agricultural resource base and threaten the sustainability of these systems. Crop mixture is an important method of high production in agriculture. This technique can affect the environmental conditions of the soil. Sustainable Agriculture, said to be the proper management of agricultural resources which in addition to changing human needs, maintaining environmental quality and capacity of soil and water resources. In order to study the effect of intercropping on the yield of maize and potatoes an experiment as 14 treatment in a randomized complete block design with three replications as replacement and additive approach has been conducted in the region of Nikshahr in 2013. The experimental treatment consisted of sole corn (T1), sole potato (T2), two-row corn + one-row potato (T3), two-row corn + two-row potato (T4), one-row corn + one-row potato (T5), one-row corn + two-row potato (T6), two-row corn + two-row potato (T7), (The difference T7 and T4 is that in T4, for each product optimal plant population density is 50%, while in T7 for both products 100% high density will be used), three-row corn + one-row potato (T8), one-row corn + three-row potato (T9), three-row corn + two-row potato (T10), two-row corn + three-row potatoes (T11), two-row corn + four-row potatoes (T12), four-row corn + two-row potato (T13), two-row corn + two-row potato (T14), (The difference of this treatment with T4 and T7, is that in this treatment optimal plant density was 100% for corn and 50% favorable for potato was used). Traits for corn included plant height, number of ears per plant, number of grains per ear, number of grains per row, number of rows per ear, grain yield and 1000 grains weight and for potatoes, including plant height, tuber weight and the number of tubers per plant. The results showed that, different planting systems on the number of grains per ear, number of grains per row and grain yield and plant height and size of potato tubers were significantly affected and improved the characteristics of plants have been mentioned. The highest biological yield (12.61 t.ha-1) of sole corn cropping (T1), respectively. Reduced biological function of monoculture corn compared to intercropping in this experiment can be attributed to inter-species competition of peanuts and corn. The highest grain yield (8957.3 kg.ha-1) was observed in treatment (T3). Production due to reduce competition between species, compared to the competition within the species increased. Most weight tubers of potato (73.54 g) treatment (T2), respectively. Potato tuber weight loss in the intercropping to monoculture in this experiment can due to inter-species competition potatoes and corn. The highest land equivalent ratio in one- row potato + three-row corn (T8) was obtained which shows the superiority of intercropping to monoculture. The results of variance analysis showed that:Intercropping of maize and potatoes with increasing plant density, increased the grain yield of both crops in monoculture and mixed culture which could be due to increased vegetation and it's closer to optimum density in mixed culture and better use of environmental resources.
Reduced grain weight with increased density often is the result of intensified competition intra-species over the use of existing resources. Corn in different densities is able to take advantages of photosynthetic material and grains of similar weight at different densities produce.
In monoculture of potatoes because the only governing competition is intra-species so the plant is not affected in much higher density. Reducing the height of potato plants in intercropping to monoculture in these experiments can be attributed to intr-species competition of potatoes with corns.
In monoculture because only intra-species competition is dominant so the tuber weight is not affected in higher densities. Due to fact that the monoculture system has been threated, the benefits of providing better distribution of light in the canopy, Suitable spatial distribution of shrubs and reducing competition between plants to use environmental factors to provide an appropriate manner, as a result significantly increase economic yield.
The LER in most intercropping was more than one which indicates the superiority of intercropping to monoculture.