Abstract: 【Objective】Fruit cracking is the most serious physiological disease in the production of Chinese jujube, the objective of this study was to screen and evaluate the germplasms with high resistance to cracking. These germplasms would provide materials for planting and breeding of Chinese jujube directly.【Method】The cracking resistance of 169 cultivars were evaluated for 5 years by comparison of cracking type, cracking rate and degree of cracking extent. Then, the fruit microstructures of cultivars with different degrees of cracking resistance were compared by using paraffin slice. 【Result】The grading system of jujube fruit cracking was established according to the length and area of fruit cracking. Statistical analysis of four fruit cracking types showed that longitudinal crack was the main type. Some resistant cultivars, such as Huluchangzao, Guantanzao, Hebeilongxuzao, Chahuzao, Xuezao, Jianzao, Chuanlingzao, Chengwudongzao, Zhongyangtuanzao, Hongzhaocuizao, Mianxuzao, Lengzao, Shaizao, Wanniunaizao, Nanjingdamuzao and Mopanzao, were screened out. The fruit structures of cultivars with different cracking resistance degrees were significantly different. The peel epidermis layer of resistance cultivar is of uniform thickness, with cells closely arranged in neat rows. The weaker the resistance to fruit cracking, the unevener of the peel epidermis layer, and the more unordered the cells. 【Conclusion】 Several cultivars with high resistance to fruit cracking were found. The resistance to fruit cracking is positively correlated to the density and uniformity of fruit epidermal cells but not the density of pulp cells.

Key words: jujube , physiological disease , fruit cracking , germplasm screening , evaluation