Effects of Irrigation Regime on the Tomato Biomechanics: A Texture Investigation for Fruit Cracking Mechanism

To investigate the effects of irrational irrigation on tomato yield and quality, and the effects of different irrigation regimes on tomato biotexture mechanics, irrigation experiments were carried out in greenhouses, focusing on the two factors of irrigation frequency and irrigation quantity. Results showed that when the irrigation regime was A1 (150% ETc, 1 time/interval 1 day) or E3 (50% ETc, 1 time/interval 13 days), the fruit cracking rate was up to 69.53%; when the irrigation regime was C3 (50% ETc, 1 time/interval 5 days), the cracking rate was as low as 8.75%. Irrigation regime also had significant effects on the mechanical indicators. Meanwhile, the irrigation regime significantly affected the content and status of pectin in the cell wall but had no significant effect on hemicellulose and cellulose. With a short irrigation cycle and large irrigation amount, WSP (Water‐soluble Fraction) increased, CSP (CDTA‐soluble Fraction) and NSP (Na2CO3‐soluble Fraction) decreased, and the fruit was easy to crack. The crystallinity, supporting power, and cracking resistance of pectin polysaccharides in C were strong, while those in A, B, D, and E were opposite. Research showed that the cracking of tomato induced by irrigation was due to the change of the composition and structure of the polysaccharide in the cell wall. This study can provide a reasonable irrigation regime such as C3 treatment for fruit farmers, which has the effect of both saving water and improving quality. The screened mechanical phenotypic indexes are conducive to reverse localization of crack control genes and enhancing tomato crack resistance breeding level.