Study of Agronomic Traits, Yield Performance and Economical Indices in Intercropping of Spinach with Chickpea

 Due to the limits of the conventional agricultural system, intercropping is important in terms of production sustainability. Intercropping plays an important role in increasing production and performance stability to improve the use of resources and environmental factors. Spinach (Spinacia oleracea L.) is an important leafy vegetable, of which the leaves and tender shoots are consumed fresh or processed. Spinach is native to Iran. Spinach contains different flavonoids that function as antioxidants and anticancer agents. Also, spinach may be used in the prevention of Alzheimer's disease. It is an annual plant and as well as chickpea, spinach is grown as both an early spring and late fall crop in order to have growth at the coolest parts of the season. Spinach seed yield varies based on the climatic conditions, optimum sowing date and chose of the best planting pattern. Considering that the intercropping of this plant has not been studied with legumes such as chickpe, this experiment was designed to determine the possibility of intercropping spinach with chickpea using agronomical and economical indices, as well as determining the best planting pattern.

 In order to investigate agronomic traits, yield and economical indices in spinach intercropping with chickpea, an experiment was carried out as a randomized complete block design with four treatments and three replications in 2017-18 growing season in Tuyserkan city, Hamedan province. In this city, spinach is mainly cultivated for seed production. Experimental treatments included additive intercropping of 20% chickpea with spinach, replacement intercropping of 60% spinach + 40% chickpea and pure stand of spinach and chickpea. Plant height, number of branches per plant, number of seeds per plant, 1000 seed weight, grain yield and biological yield in spinach, as well as plant height, number of branches per plant, number of pods per plant, number of seeds per pod, 1000 seed weight, grain yield and biological yield in chickpea were measured. To compare the advantages of intercropping of spinach with chickpea, the land equivalent ratio (LER), dry matter equivalent ratio (DMER), system productivity index (SPI), competitive ratio (CR), aggressivity (AG), actual yield loss (AYL ), relative value total (RVT), monetary advantage index (MAI) and intercropping advantage (IA) were calculated and evaluated. SAS 9.1 software were used for analysis of variance (ANOVA) calculations. The difference between the means was evaluated by the least significant difference (LSD) method at the level of 5% probability.

Plant height, number of branches per plant, 1000 grain weight and grain and biological yields of spinach were significantly affected by intercropping. The highest plant height and the lowest number of branches per spinach plant were obtained from the replacement intercropping. Additive intercropping and pure stand of spinach without significant difference had the lowest plant height and the highest number of branches per plant. The highest 1000 grain weight and grain yield of spinach were associated with the additive intercropping method. However, in terms of biological yield, the pure stand of spinach showed the highest results. Notably, there were no significant differences between the treatments of additive intercropping and pure stand of spinach concerning grain and biological yield of spinach. On the other hand, in chickpeas plants, intercropping had a notable impact on various parameters. Specifically, plant height, number of branches per plant, number of pods per plant, 1000 grain weight, and both grain and biological yields were affected by the intercropping method. Among these, the additive intercropping treatment resulted in the highest plant height, while it had the lowest number of branches and number of pods per chickpeas plant.The highest 1000 grain weight and grain yield of spinach were related to the additive intercropping. Pure stand of spinach had the maximum biological yield. Treatments of additive intercropping and pure stand of spinach were not significantly different in terms of grain and biological yield of spinach. In chickpeas plant, plant height, number of branches per plant, number of pods per plant, 1000 grain weight, grain and biological yields were affected by intercropping. The highest plant height and the lowest number of branches and number of pods per chickpeas plant were obtained at the treatment of additive intercropping. Maximum grain and biological yields of chickpea were belonged to the pure stand of chickpea. Spinach and chickpea were dominant and recessive plants, respectively. Evaluation of the economical indices also showed the advantages of spinach intercropping with chickpea at both intercropping design (replacemet and additive intercropping). So that the highest values for land equivalent ratio, dry matter equivalent ratio, system productivity index, actual yield loss, relative value total and monetary advantage index were achieved at additive intercropping system. But, the lowest values for these indices (1.13, 1.06, 1.20 and 1321 for LER, DMER, RVT and MAI, respectively) were revealed at replacement intercropping.

 Overall, the results indicate that chickpea is a suitable plant for intercropping with spinach. So that the intercropping of 20% chickpea with spinach improved the yield performance of spinach and land-use efficiency and can lead to the greatest economical profit.