Effects of water deficit combined with soil texture, soil bulk density and tomato variety on tomato fruit quality: A meta-analysis

Abstract

Tomato is a popular healthy fruit worldwide because it is rich in secondary metabolites such as vitamin C. Deficit irrigation (DI) can be applied to improve tomato fruit quality to a certain degree and save water consumption. However, the effects of DI on tomato quality are complex and affected by factors such as tomato variety and soil bulk density and texture. The objective of this paper is to use meta-analysis to 1) investigate the effects of DI on tomato quality variables and 2) study how soil texture, soil bulk density and three tomato varieties affect quality variables under DI compared to those under full irrigation. We collected 83 research papers from around the world and analyzed 2369 data pairs. Overall, DI increased the total soluble solids (12.44%), soluble sugar (11.23%), organic acids (6.58%), sugar/acid content ratio (14.56%), vitamin C (13.84%), lycopene (10.46%), color index (8.42%), red-green value (11.89%), shape index (3.25%) and firmness (12.09%) while decreasing β-carotene, lightness, hue angle and yellow-blue value by 11.11%, 1.77%, 3.42% and 4.26%, respectively. In addition, DI had no significant effects on tomato chroma (0.89% on average; 95% CI: -0.96% to 2.79%) or pH (0.13% on average; 95% CI: -0.26% to 0.52%). The results indicated that it would be better to apply deficit irrigation in fine and coarse soil, because most of the quality variables improved more in these soil textures than in medium soil. Soil with a bulk density of 1.2∼1.4 g cm-3 benefited taste quality, vitamin C and shape index. The quality of the three tomato varieties responded differently to water deficit conditions. Moreover, cherry tomato responded better to water deficit conditions than the other two tomato varieties; four quality variables improved the most in cherry tomato and two other variables were also improved. Our findings could help to obtain a better understanding of how fruit quality responds to DI in different soil textures, soil bulk densities and tomato varieties and to produce higher-quality tomatoes.