关键词: 梨(Pyrus spp.), 裂果, 干物质含量, 钙含量, 水分变化

Abstract: Fruit cracking is a common physiological disorder in pear production, closely related to peel mechanical strength and water fluctuations. In this study, the cracking susceptible pear germplasm ‘4-5-73' and its non-cracking parents ‘Jinshui No.1' and ‘Hosui' were used as materials. From the 4th week after full bloom until fruit maturity, fruit growth dynamics, dry matter content and calcium content in peel and flesh were determined. The results showed that the cracking susceptible variety ‘4-5-73' exhibited higher growth rates than its two parents during the young fruit stage and early fruit expansion stage, and its fruit transverse diameter was larger than that of the parents throughout the developmental period. This variety started cracking from the 9th week after full bloom, and the cracking rate increased rapidly from the 12th to the 13th week. Dry matter analysis revealed that the lowest peel dry matter content of non-cracking parents occurred at week 13, whereas that of ‘4-5-73' occurred at week 14, about one week later than that of the non-cracking parents. Lower dry matter content indicated higher water content. The peel dry matter of the cracking variety declined from peak to trough within 3 weeks, which was shorter than that of the non-cracking parents (4 weeks), suggesting a more drastic water fluctuation per unit time. Calcium content analysis indicated that peel calcium content was higher than flesh calcium content, and calcium content in all varieties decreased during fruit development. During the rapid increase of cracking, the cracking samples of the susceptible variety had lower peel and flesh calcium contents than the non-cracking samples at the same stage. Pear fruit cracking may result from the combined effects of low calcium in the peel and water fluctuations during fruit expansion: low calcium weakened the mechanical strength of the cell wall, while rapid water accumulation generated high pressure, eventually leading to peel rupture. This study provided a theoretical basis for applying exogenous calcium fertilizer to alleviate pear fruit cracking.

Key words: pear(Pyrus spp.), fruit cracking, dry matter content, calcium content, water dynamics