Application of the 4R nutrient stewardship concept for growing off-season tomatoes in high tunnels

摘要

Abstract: This study aimed to adopt the concept of 4R nutrient stewardship for growing off-season tomatoes in high tunnels. The tomato crop (Hybrid ‘Sahel’), grown in high tunnels, was applied with NPK fertilizer at the rate of 80:80:90 kg ha-1 (after each 15, 30 and 45 days interval) for four months and its effect on tomato yield and quality parameters was investigated. Application of NPK at 15 day intervals resulted in the highest nutritional quality of fruit (NPK uptake 4.32 kg m-2, total soluble solids 5.6°Brix, total acidity 0.43%, protein content 15.31%, β-carotenes 0.86 mg 100 g-1, total phenolics 2.34 mg 100 g-1, total flavonoids 7.14 mg 100 g?1, antioxidant activity 83.77%) and improved shelf-life (~ 10 days). However, NPK application at 15 day intervals was not economical in terms of total fertilizer cost incurred and subsequent yield obtained. Application of NPK at 30 day intervals was the most economical (value-cost ratio 9.0 PKR) among all application intervals. This study suggested that implementation of the concept of 4Rs i.e., right source, right rate, right placement and right timing of fertilizer application is an effective tool for the production of high quality off-season tomatoes in high tunnels.