Investigating the effect of combination vermicompost and superabsorbent on quantitative and qualitative yield of cowpea (Vigna unguiculata L.) under drought stress conditions

Introduction The cowpea (vigna unguiculata L.) as a grain, grown in tropical and sub-tropical countries, especially in the countries of Asia, Africa and South America, is considered an important source of nutrition. Among beans, in terms of cultivars and economic value, the first place belongs to beans. Good climate (warm to moderate summer) and adequate water in the areas under beans, high quality soils and high depth of clay are the main reasons for increasing its cultivation area. Water is a key factor in the production of crops. The yield of crops in many areas is limited by living or non-living environmental stresses, and therefore, there is a significant difference between actual yield and yield potential of crops. Low moisture content in each of the different stages of growth reduces water absorption, nutrients, decreases the transfer of elements within the plant, and ultimately reduces the yield of the grain or the final product. Optimal use of water is of great importance, especially in areas where dry climatic conditions and Semi-dry is dominant. Therefore, the present study aimed to investigate the effects of vermicompost and superabsorbent on the quantitative and qualitative yield of bean under drought stress in Khorramshahr area. Materials and methods This research was carried out in 2017 in a farm located in Khorramshahr with a longitude of 48 degrees and 12 minutes east and 30 degrees and 22 degrees north latitude and 3 meters above sea level. This study was carried out as split split plot in a randomized complete block design with four replications. Experimental treatments consisted of drought stress in two levels (65 and 130) mm evaporation from class A evaporation pan in main plots and the combined effect of biological fertilizer of vermicompost and superabsorbent at four levels (non-application of fertilizer (control), 5 t/ha vermicompost Compost + 75 kg/ha superabsorbent, 5t/ha vermicompost + 100 kg/ha superabsorbent, 5 t/ha vermicompost) in sub plots. Results The results showed that drought stress had a significant effect on grain yield, number of pods per plant, number of seeds per pod and protein yield. Also, the combined effect of biological fertilizer of vermicompost and superabsorbent had a significant effect on grain yield and protein yield. The highest grain yield (202.22 g/m2) was obtained from treatment with 5 tons per hectare of vermicompost + 100 kg/ha superabsorbent (which did not have a significant difference with 5 tons per hectare of vermicompost + 75 kg/ha superabsorbent) and lowest with mean 174.26 g/m2 was obtained from non-application of fertilizer treatment. The interaction of drought stress and combined effect of biological fertilizer on vermicompost had a significant effect on grain yield. The highest grain yield was obtained with an average of 29.225 kg/ha of irrigation after 65 mm evaporation from the pan and 5 tons per hectare of vermicompost + 75 kg/ha superabsorbent. Conclusion Due to the fact that in the field of crop production, the true value depends on the quality of the crop, in this research it was determined that the use of vermicompost manure plays an important role in the development of the bean plant, Also, considering that the highest amounts of grain and protein yield were obtained as a quantitative and qualitative yield of vermicompost and superabsorbent fertilizer, it can be concluded that using these treatments without the slightest environmental damage and maintaining sustainability and health the agricultural system can meet the nutritional needs of the plant to a large extent. In order to achieve maximum yield and quality, in terms of humidity planting cowpea consumption of 5 tons per hectare and 75 kg ha super vermicompost fertilizer to increase the yield of cowpea is recommended for plants.