Preliminary Study On Regulating Mechanism Of Boron And Calcium To Apple Fruit Development

Mains pumila cv Fuji of apple fruit was used as the materials in the experiment. The treatment of experiment was spraying leaves with 0.2% H3BO3 at different developing stage of 'Fuji' fruit. The content of calcium and boron could be improved by treatment, which indicated that boron could freely transport by phloem and improved the content of calcium. By the short effect of treatment on the fruit absorbing boron, the treatment order was the young fruit stage > the rapid growing phase of the fruit > ripening phase. But the effect of treatment on the ripening phase of fruit, the order was the rapid growing phase of the fruit > ripening phase>.the young fruit stage. The content of boron and calcium of cell wall in the fruit could be improved by treatment. At the same time the content of Mg, Fe and Mn could be enhanced by treatment ,on the contrary, the content of K could be inhibited.The absolute contents of different boron forms in fruit were enhanced by spraying leaves with H3BO3.The three boron forms were water soluble boron, semi-bound boron and bound boron. With the development of fruit proportion of water soluble boron and semi-bound boron was higher, on the contrary, proportion of bound boron is lower.Polar diameter was longer than control at the earlier stage of developing fruit by treatment, but eguatorial diameter was longer at the later stage of developing fruit. Spraying H3BO3 increase the content of soluble sugar and the soluble solid, decrease the tartaric acid content of fruit. The best stage for spraying was the stage of fruit ripening.In the different developing stage of 'Fuji' fruit, activities of soluble acid invertase (SAI) and soluble neutral invertase (SNI) and contents of Calmodulin ( CaM) were analyzed in order to find out the changes in apple fruit development .The results showed that activities of SAI and SNI had dominant changes in the fast growth phase, but that of content of CaM have not; The experiment of excised tissue discs showed that cellular Ca2+ regulated the activities of SAI and SNI by CDPK (calcium binding protein kinase) at the rapid growing phase of fruit, but not during the fruit ripening. The activities of SAI and SNI were significantly increased by CaCI2 and A23187, and significantly inhibited by EGTA. Moreover, The activities of SAI and SNI were not enhanced by PS and CaM, but that were significantly inhibited by W7 and K252a. So, the results showed that Calcium regulates the activities of SAI and SNI by CDPK.