Application of Box-Behnken Design in Optimization of the Okra (Abelmoschus esculentus L.) Plant Growth in Loamy Sand Soil

Abstract

Seedling emergence and its vigor index are the decisive steps for increasing vegetable crop yield performance using a sustainable approach. Response surface methodology (RSM) is an effective statistical method used to determine the significance of independent variables and the range of optimum conditions to maximize seedling growth in large-scale plant production. In this study, the RSM method was used to predict the maximum germination percentage and seed vigor index of an okra (Abelmoschus esculentus L.) plant in loamy sand soil. A Box-Behnken design of RSM having 15 triplicated runs was designed for okra seed germination experiments. A second-order polynomial model having three levels of biochar (10, 5.5, and 1%), cow dung (10, 5.5, and 1%), and water content (100, 70, and 40%) was used to optimize okra seed germination and seed vigor index. We evaluated the individual effect of biochar and cow dung manure on β-glucosidase and alkaline phosphatase activity in the soil. The results showed that the water content had a significant influence on the selected response variables. Based on the plant growth studies, the use of 5.5% of both biochar and cow dung concentration and 70% of water content in the soil resulted in the highest germination percentage and seed vigor index of 93% and 2479. The ANOVA studies revealed good agreement between the experimental data and the proposed model, indicating the suitability of the employed model in optimizing germination conditions. Enzyme activity analysis revealed that the amendment of 10% cow dung enhanced 55% β-glucosidase activity compared to control, while the application of 5.5% biochar along with cow dung improved 29% of alkaline phosphatase activity. The current study found that applying biochar and cow dung manure while maintaining water content can improve okra seedling emergence and growth in loamy sand soil. Future research includes long-term field experiments and studies on various biochar and their suitability for other soil types. Moreover, the RSM method can be used to study the effect of parameters like oxygen content, salt, heavy metals, and humus substance in soil on plant growth. © 2023, The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo.