The effect of cropping pattern and manure rates on competitive indices and yield of spinach (Spinacia oleracea L.) and garlic (Allium sativum L.)

 Intercropping is cultivation of two or more crops in a land in a growing season that the important goal of this is optimal use of growth resources and labors. The most important advanteges of intercropping is higher yield in a certain land by using the various traits such as canopy structure, the ability of root development, height, nutritional needs and efficient use of growth resources. The studies show that the responses of plant species were different in intercropping and monoculture cropping systems. The present research aimed to investigate the planting pattern and different levels of manure on competitive power and agronomic traits of garlic and spinach. This experiment was conducted as split plot based on completely randomized block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, during growing season of 2011-2012. The treatments were manure rates at three levels (0, 10 and 20 ton.ha-1) in main plots and 6 cropping systems (garlic and spinach monocultures and garlic-spinach intercropping with 1:1, 2:2, 3:3 and 4:4 ratio) in sub plots. Studied traits were included in height, fresh and dry weight of spinach and garlic, Land Equivalent Ratio, Aggressivity Coefficient and Competition Ratio. The results indicated that with increasing manure level to 20 ton per hectare, spinach fresh weight increased, significantly but this trend wasn’t observed in spinach dry weight. Also with changing cropping pattern, dry and fresh weight of spinach was affected, significantly. The highest dry and fresh weight of spinach was observed in garlic and spinach intercropping with 4:4 ratio. The investigation of interaction effect of planting pattern and manure showed that the highest fresh and dry weight of spinach were obtained in garlic and spinach intercropping with 1:1 and 4:4 ratio under 20 ton per hectare manure, respectively. The lowest spinach dry weight was in garlic and spinach intercropping with 3:3 ratio under 20 ton per hectare manure. Garlic dry and fresh weight wasn’t affected by manure rates, but cropping pattern affected dry and fresh weight of garlic, significantly. The highest fresh and dry weight of garlic was obtained in garlic monoculture without manure.In studied intercropping systems, land equivalent ratio (LER) was more of one. The highest LER was obtained in intercropping with 3:3 ratio without manure Conclusions In general, the best treatment for Aggressivity Coefficient, Competition Ratio and Land Equivalent Ratio was obtained in garlic and spinach intercropping with 1:1 ratio and 20 ton per hectare manure.