Influence of Different Fertilizers and Water Stress on Sorghum Yield and its Components

Abstract

Sorghum is a vital forage crop in the cereal family, known for its resilience in dry conditions and high water use efficiency, leading to desirable yields even under drought stress. In order to further understand the dynamics of grain sorghum production, this study was conducted over two agricultural years (2019 and 2020) in Khorramabad. The experiment utilized a split-plot factorial design with four replications, employing a randomized complete block design. The study investigated the impact of drought stress and fertilization management on grain sorghum production. Drought stress was imposed by cutting off irrigation at three levels, including normal irrigation and irrigation at the vegetative and reproductive stages. The secondary factor involved a factorial design incorporating three levels of organic fertilizer, namely vermicompost, chemical fertilizer based on soil test, and combined use of vermicompost and chemical fertilizer. Two cultivars of Sepideh and Kimia were used in subplots. Data collected included yield per hectare, plant height, stem diameter, and number of days to maturity. A combined analysis of variance was initially performed to analyze the impact of stress, cultivar, and fertilizer on the quantitative, qualitative, and phenological indices of grain sorghum. Due to non-significant effects of year and year interaction in different factors, the analysis was based on the mean of two years. The results demonstrated significant effects of stress, cultivar by stress interaction, and fertilization on the measured traits. Particularly limited irrigation during the reproductive stage, stress had a negative influence on the crop's quality and yield. Conversely, the application of vermicompost fertilizer significantly improved the studied traits. Additionally, the Sepideh cultivar outperformed the Kimia cultivar in all parameters except protein ratio. Under imitated irrigation during the vegetative stage, the yield of Sepideh cultivar was 8 tons per hectare, while Kimia cultivar yield was 4.36 tons per hectare. Similarly, under drought stress during the reproductive stage, the yield of Sepideh cultivar was 7.67 tons per hectare, and Kimia cultivar yield was 4.54 tons per hectare. Overall, this research highlights the importance of effective crop management practices for moderating the adverse effects of stress on grain sorghum production.