The Impacts of Controlled Irrigation on Water Consumption, Yield and Fruit Quality of Substrate-cultivated Pepper (Capsicum annuum) in Gobi Desert

Abstract

【Background】 Water scarcity is a bottleneck hindering vegetable production in Gobi Desert. While previous studies have shown implementing water-saving irrigation is one solution, most existing studies on crops in this region focused on soil-cultivation. In contrast, water consumption of substrate-cultivated vegetable production in greenhouse has received limited attention despite its increased use. 【Objective】 Taking pepper (Capsicum annuum) as an example, the purpose of this paper is to fill this knowledge gap by systematically studying the impact of matrix saturation combined with controlled irrigation implemented at different growing stages on yield, fruit quality and water consumption of the crop. 【Method】 The experiment was conducted from autumn to winter in a solar greenhouse at Hexi corridor, with the cultivar Longjiao No.11 used as the model plant. We compared three irrigation treatments by keeping the matrix saturation at 50%～60%, 60%～70% and 70%～80% respectively at different growth stages, with matrix saturation kept at 70%~80% in the whole season taken as the control. Controlled deficit irrigation was implemented at seedling, initial flowering, initial fruiting and full fruiting stages. In each treatment, we measured water consumption, yield, fruit quality and water use efficiency of the peppers. 【Result】 The total water consumption and daily water consumption of the peppers both increased with the matrix saturation, and the water consumption modulus at each growth stage increased as time elapsed The shoot height, stem thickness, soluble sugar and protein content, vitamin C (Vc), nitrate and fruit yield were most sensitive to irrigation regulation at the seedling and fruiting stage. Compared with the treatment maintaining matrix saturation at 70%～80% in the whole season, temporally keeping matric saturation at seedling and fruiting stage at 70%～80%, with deficit irrigations conducted at the initial flowering and early fruiting stage, can increase the contents of soluble protein and Vc, yield, and water use efficiency of the crop by 5.59%, 5.82%, 6.43% and 18.77%, respectively, while reducing nitrate content by 0.89%. 【Conclusion】 Keeping the matrix saturation at 70%～80% during the seedling and fruiting stages, and thirsting the crop at initial flowering and fruiting stages by keeping the matrix saturation at 50%～60% and 60% to 70%, respectively, was most effective in saving water and improving yield and fruit quality, as well as the water use efficiency. It can be used as an optimal cultivation for solar greenhouse production of matrix-cultivated peppers from autumn to winter in the Hexi corridor.

Keywords

• gobi desert
• capsicum annuum
• substrate culture
• water regulation
• high quality and efficiency
• irrigation mode