Abstract: [Objective] Chinese jujube (Ziziphus jujuba) fruit is easy to crack at ripening stage during rainy season, which brings huge economic loss to the production. This study aimed to clarify the main ways of water absorption leading to jujube fruit cracking, and provide a basis for further exploring the mechanism of fruit cracking and its prevention and control.[Method] The experiment was carried out from 2013 to 2015. Fruits of Z. jujuba ‘Huping’ with higher cracking susceptibility were used as test materials. The water absorption distribution of different parts of the jujube fruit was observed with dye tracer and stereoscope. The possible ways of water absorption of jujube fruits were determined, and the differences of water absorption per unit time in different parts of jujube fruits were determined by sealing the different parts of the fruit with wax and then incubating them in water. The surface structure characteristics of jujube fruit were observed with stereoscope and scanning electron microscope, and the relationship between surface structure characteristics and water absorption and fruit cracking of jujube fruit was analyzed as well.[Result] 1) The surface, stem and stalk cavity of ‘Huping’ jujube fruits were able to absorb water, and during the fruit coloring period, their relative water absorption accounted for 51%-54%, 31%-40% and 9%-18% of the total relative water absorption of the fruits, respectively. 2) In the process of fruit development and maturation, the fruit surface stomata were corked to form lenticels and some of the lenticels formed microcracks. At that time, water absorption on the fruit surface doubled and water could enter the fruit through open lenticels and microcracks by both symplastic and apoplastic pathways. 3) It was generally observed in both natural rainfall and water-incubation experiment that macroscopic cracks were connected in a line by more than two fruit points, and the cross point of cross cracks was the location of the fruit spot. The above results proved that jujube fruit surface stomata were the inducement of microcracks.[Conclusion] During the fruit maturation process, the lenticels and microcracks formed from stomata on jujube fruit surface were the main ways for the fruit to absorb water, and they were also the main causes of water absorption and cracking of jujube fruit. On the jujube fruit surface, there existed both symplastic and apoplastic pathways by which water entered the fruit.

Key words: Chinese jujube(Ziziphus jujuba), water absorbing pathway, lenticels, microcracks, fruit cracking