Abstract: 【Objective】In order to provide a reliable evidence for better understanding the mechanism of fruit cracking, the changes of anatomical structure and the transport efficiency of xylem vessels in stalk during Huping jujube development were studied. 【Method】 The soil water content was measured and the Huping jujube was irrigated by quantitative calculation at white-ripe stage. The soil water content of irrigation treatment and CK were kept of (80%±5)% and (20%±5)% by controlling irrigation. The cracking rates were investigated before and after rainfall, and the crack length more than 5 mm and lost business values was considered as fruit cracking. The sampling was finished at young fruit stage, white-ripe stage, part-red stage and full-red stage, respectively. The changes of transport efficiency of vessels in secondary branches, shedding shoot and stalk were studied by magenta tracer. In order to find out the changes of anatomical structure of vessels in stalk during the fruit development, the stalk were sampled and fixed in FAA fixative, conventional methods of embedding, making slices, fast green and safranin staining. 【Result】 The cracking rate of CK and irrigation treatment were 2.60% and 2.58%, respectively, and there was no significant difference between CK and irrigation treatment before rainfall. The rapid increasing of cracking rate was occurred after rainfall, and the cracking rates of CK and irrigation treatment were 42.9% and 40.80%, respectively, while there was no significant difference between the two treatments. The results of magenta tracer showed that the speed of magenta solution transport depend on fruit developmental periods, while it could be transported to the shedding shoot at any stage of fruit development. During the young fruit stage, magenta solution could be transported into the fruit in 5 minutes, and the quantity and distribution were increased with the soaking time, while it would take 40 minutes at the white stage, and it was nearly couldn’t be seen at part-red stage and full-red stage fruit. The above results indicated that the stalk maybe the main obstacle of magenta solution transport. During the fruit development, the percentage of the normal vessels reduced from 97.22% at young fruit stage to 34.95% at white stage, and the percentage reduced to 13% rapidly at part-red stage and full-red stage. The results of paraffin slice indicated that there were breakage, degeneration and blocking appeared in xylem vessels of stalk at white stage, and it kept getting worse during the fruit development. While the blocking was observed at part-red stage, and they were increased in numbers and extent at full-red stage.【Conclusion】All the results of this study suggested that the breakage, degeneration, malformation, and blocking in xylem vessels of stalk were appeared at the late development stage of Huping jujube, and the transport efficiency of xylem vessels was decreased or lost, which results in the transport blocking of water absorbed by root through “root-stem-secondary branch-shedding-stalk-fruit”. Endogenous water can’t cause a lot of fruit cracking.

Key words: Huping jujube, fruit cracking, stalk, xylem vessel