Foliar application of animal based-protein hydrolysates enhances growth performance, yield, and fruit quality of tomato under deficit irrigation in greenhouse

Appropriate deficit irrigation is a water-saving irrigation strategy that can improve tomato fruit quality, but excessive water deficit always leads to yield reduction. It is an urgent task to seek an appropriate strategy that can address the negative impact of deficit irrigation on tomato yields while maintaining high fruit quality. A pot experiment was conducted on drip-irrigated greenhouse tomato to explore the roles of foliar pig blood-derived protein hydrolysates (PP) on the yield, water use efficiency, and fruit quality of tomatoes under normal irrigation (70–75 % field capacity) and deficit irrigation (45–50 % field capacity). The results revealed that PP application strengthened the beneficial effects of deficit irrigation on tomato quality by increasing the levels of soluble solids, sugars, protein, carotenoids, total phenols, and anthocyanins in fruits as well as fruit color and firmness. The negative effects of deficit irrigation on tomato yield were alleviated after PP application, which increased tomato yield by 18.2 % and water use efficiency by 18.8 %, alongside improvements in chlorophyll content, carotenoid content, and photosynthetic parameters. PP also increased the ascorbic acid, glutathione, total phenolic, and flavonoid contents and thereby significantly reduced the malondialdehyde content in tomato leaves caused by deficit irrigation. Therefore, the combined management of protein hydrolysates and deficit irrigation is a win win method to increase tomato quality and maintain yield in modern sustainable agriculture. • Pig blood-derived protein hydrolysates improved water use efficiency in tomato under deficit irrigation. • Pig blood-derived protein hydrolysates reduced oxidative stress and improved tomato growth under deficit irrigation. • Pig blood-derived protein hydrolysates attenuated the tomato yield reduction caused by deficit irrigation. • Pig blood-derived protein hydrolysates increased tomato fruit quality under deficit irrigation.