Sweet peppers yield and quality as affected by biochar and compost as soil amendments under partial root irrigation

Abstract

Owing to the arid and hot climate of Saudi Arabia, the use of water saving strategies in regional agriculture is imperative. This study aims to investigate the use of the partial root-zone drying (PRD) method in combination with the application of biochar (BC), compost (comp), and the combined application of both to improve the marketable yield and fruit quality of bell peppers grown in protected agriculture. Pepper plants were grown under full irrigation (FI, 100% ETc) and partial root-zone drying irrigation (PRD, 80% ETc) regimes and seven different levels of organic soil amendment: 2% BC, 2% Comp, 4% BC, 4% Comp, 1% BC + 1% Comp, and 2% BC + 2% Comp (w/w). We found that reduced irrigation (PRD) resulted in significant decreases in the average length, width, and wall thickness of fruit and reduced early, marketable, and total yields. However, several indicators of fruit quality were improved under the PRD irrigation regime, with fruit also having higher dry matter, vitamin C, and TSS content, and increased total acidity and total sugars values. In addition, PRD increased the N and Ca content of the fruit relative to fruit grown under the FI regime. The combined application of BC 2% + Comp 2% had positive effects on fruit length, width, and wall thickness and improved early, marketable, and total yields. The treatment also increased fruit dry matter, vit. C, TSS, TA, and TS, and improved fruit N, P, and Ca concentrations. Thus, the application of BC 2% + Comp 2% in combination with PRD could be used to increase fruit quality and yield in sweet pepper production while reducing the amount of required irrigation water by 20%. We conclude that the application of both BC and comp in combination with PRD is a novel and promising approach to improving fruit quality and yield in sweet pepper protected agriculture.