Effects Of Abscisic Acid And Ethylene On Ripening Of ’Taishan Zaoxia’ Apple

’ Taishan Zaoxia ’ is a new precocious apple cultivar with early maturity，beautifulappearance and excellent quality characteristics．When Taishan Zaoxia was deposited at roomtemperature for3-5days after harvesting、with the fruit coloring2/3and reaching maturitynine and ten，it became softeningor even bursting.’ Taishan Zaoxia ’ has unique characteristics.The coloring and anthocyanin both are important indicator of ’ Taishan Zaoxia ’ fruit maturity.In recent years， the results show that the texture，flavor and appearance quality of ’ TaishanZaoxia ’ apple fruit were subject to the ethylene control，belonging a very ethylene sensitivetype. Therefore，to further explore the upstream endogenous regulatory factors of the ethylenein fruit ripening is important for comprehensive understanding of ’ Taishan Zaoxia ’ applequality regulation mechanism. we selected the later stage of development Taishan Zaoxiaapple as the test material to discuss the effects of the exogenons ABA，fluridone (ABAbiosynthesis inhibitor) and ethephon on fruit ripening.The results showed that:1. Under different treatments in the late stage of development of Taishan Zaoxia apple，anthocyanins，soluble sugar and titratable acid content were determined. The results showedthat the anthocyanins and soluble sugar content showed an ascending trend，the titratable acidcontent showed a downward trend in the late stage of development of fruit；ABA biosynthesisinhibitor fluridone treatment effectively inhibited the soluble sugar and anthocyanin content，but increased the organic acid content，and there are obvious differences among differenttreatments；Ethephon significantly increased the soluble sugar and anthocyanin content，butinhibited the increase of organic acid concentration.2. The changes of the endogenous hormone contents were determined inthe late stage of development of Taishan Zaoxia apple. The results showed that the content ofABA，GA and IAA were increased firstly and then decreased，the peak of GA and IAAcontent appeared in June21st，ABA reached the peak3days later than the former two，but3days earlier than the peak of ethylene release；The rise of ABA content resulted in thedecreasing of GA and IAA content，while caused the synchronous increasing of ETH production，suggesting that ABA had an earlier effect on fruit ripening than ETH.3. The changes of the endogenous hormone contents under different treatments weredetermined in the late stage of development of Taishan Zaoxia apple. The results showed thatthe ABA treatment increased ethylene release and the ethylene release peak appeared threedays early，the changing trends of the endogenous hormone contents under other treatmentsare consistent with the control；Of all treatments，the GA and IAA content of fluridone，treatment were the maximum，while ABA content and ETH production were the minimum，however，the contents of GA，IAA are significantly lower than the control under the ethyleneand ABA treatments，and the content of ABA and ETH release are higher than the control.4. The relationship between endogenous hormone and anthocyanin，total soluble sugarand titratable acid were determined. The results showed that there is no significant correlationbetween GA，IAA and anthocyanin，total soluble sugar，titratable acid content；there aresignificantly or very significantly positive correlation between ABA content，ethylene releaseand the changes of congtents of soluble sugar，anthocyanin，while significantly negativecorrelation with titration acid before the ethylene release peak；there are significantly negativecorrelation between ABA content and the contents of soluble sugar and anthocyanin，whilesignificantly positive correlation with titration acid after the ethylene release peak.Based on the above results，the fluridone application decreased the level of ABA，soluble sugar and anthocyanin content， increased the organic acid content inthe late stage of development of Taishan Zaoxia apple，affecting the fruit color formation andripening；the rise of ABA content resulted in the decreasing of GA and IAA content，whilecaused the synchronous increasing of ETH production，suggesting that ABA had an earliereffect on fruit ripening than ETH；Of all treatments，the GA and IAA content of fluridonetreatment were the maximum，while ABA content and ETH production were the minimum，suggesting that ABA influenced fruit ripening by regulating the biosynthesis of endogenoushormones，such as GA.IAA and EHT；Further correlation analysis found that ABA played animportant role in regulating the ripening of apple fruits upstream of ethylene.