The Relationship Between The Metabolism And Fruit Cracking During The Developmental Stages Of Zizyphus Jujuba Mill

In this study, the cracking-resistant’Yuanling’jujube (Zizyphus jujuba Mill.cv Yuanlingzao) and the susceptible’Jun’jujube were used as materials (Zizyphus jujuba Mill.cv Junzao). The anatomical structure of fruit was observed and the mineral contents and different calcium forms in pericarp were determined. Ca2+in the pericarp and flesh cells were deposited simultaneously using potassium antimonite in ’Yuanling’ and ’Jun’ jujube fruit. Endogenous hormones content in pericarp, pulp, seed were deposited using HPLC, and the activities of enzymes related to cell-wall metabolism in pericarp, pulp were determined.The observation of anatomical structure showed that the epidermal thickness of’Yuanling’variety was significantly higher than’Jun’variety at the whole developmental stages, so did for the cuticle thickness of the two varieties80and90days after full bloom. The size of epidermal cell of’Yuanling’ was significantly smaller than’Jun’jujube during70-90days after full bloom, and the size of flesh cell showed no difference between the two varieties. The contents of N, P, Mg in the pericarp of fruit were no significantly difference between this two cultivars, but the contents of K was higher during the late period of fruit development, and the Ca contents in the pericarp of ’Yuanling’ was significantly higher than’Jun’jujube during the90and100days after full bloom, especially for the content of NaCl-Ca.The distribution of Ca precipitate particles in the pericarp and flesh cell of’Yuanling’variety was massive and homogeneous40days after full bloom compared to less particles specifically distributed along the cell wall of pericarp and flesh cells in’Jun’variety. Ca2+precipitate particles in the pericarp and flesh cells90days after full bloom declined in the two varieties. Ca2+precipitate particles in pericarp cells were only distributed along the cell wall of flesh cells, while distributed unevenly in flesh cells. Almost no Ca2+precipitate particles distributed in pericarp cells of ’Jun’ jujube100days after full bloom.The GA3content in the pericarp and IAA content in the pulp of’Jun’was evidently higher than ’Yuanling’during70to100days after full bloom. The content of ABA in the pulp and seed of ’Jun’ was significantly higher than ’Yuanling’ variety, but the ABA content in the pericarp was lower than ’Jun’ The ratio of (GA3+1AA+ZT)/ABA in the pulp and seed of’Jun’was higher than ’Yuanling’ variety, the difference between them was markedly. The pectinase activity in the pericarp of ’Jun’ was clearly higher than’Yuanling’when80days after full bloom. During60to100days after full bloom, the cellulase activity in the pericarp of ’Jun’ was markedly higher than’Yuanling’variety. The POD activity in the pulp of’Jun’was significantly higher than’Yuanling’during50to100days after full bloom. PPO activity in the pericarp and pulp of Jun’were obviously higher than’Yuanling’variety.Those results above provide that the epidermal thickness and the content of Ca in the pericarp of jujube fruit was closely related to fruit cracking and NaCl-Ca was the important form of Ca in pericarp.’Yuanling’jujube has the strong enrichment of calcium during the early and late developmental stages, and the amount and distribution of Ca2+precipitate particles were closely related to fruit cracking. Accumulation of GA3promoting the generation of IAA, IAA accumulate in the pulp of fruit during the late developmental stage and ABA content in the pericarp of fruit during the high incidence cracking stage were positively correlated with the fruit cracking. The vareity which has the high ratio of (GA3+IAA+ZT)/ABA were more prone to cracking. The pectinase and cellulase activity in the pericarp of fruit during the late developmental stage affect the occurrence of the cracking. POD activity in the pulp is one of the important factors affecting fruit cracking; the PPO activity in the susceptible variety was higher than cracking-resistant variety.