Effects Of Plant Growth Regulators Applied During Growth Period On The Changes Of Volatile Organic Compounds In Huangguan Pear During Storage

Volatile compounds（VCS）,as important evaluation indicators of aroma quality,have a significant impact on the overall flavor of fruits and vegetables,and are also one of the important indicators for the judgment of harvest and storage periods.However,after long-term cold storage,the aroma of the fruit will be significantly weakened,and the problem increases with the extension of the cold storage time.At present,many experts have studied the application of plant growth regulators after harvest,and found that some plant growth regulators have obvious effects on maintaining or improving the aroma components of pear during storage.However,there is no research focus on whether the use of plant growth regulators during the growth of pome fruits affects the formation of volatile substances during fruit storage.Based on the above problems,in this thesis,three plant growth regulators（Gibberellin A4+7,brassinolide,and sodium nitrophenol）commonly used by fruit farmers during the growth period were selected to spray Huang-guan pear in the positive growth period,and the study was carried out as follows:（1）Pear fruits treated with different plant growth regulators during the growth phase were subjected to GC×GC-TOFMS aroma fingerprinting during storage.A total of 140volatile compounds including esters,alkenes,alcohols,aldehydes,ketones,alkanes,aromatic hydrocarbons and sulfides were identified.Among them,esters,alcohols,aldehydes and alkenes were the main volatile aroma components in each treatment group,but their content changes with storage time were different under different phytoregulators.When not stored,the total content of volatile compounds in gibberellin₄₊₇ treatment group was 1.72-4.68 times higher than that in other groups,and the number of volatile matter was also the most.However,after 50 days of storage,the content and quantity of volatile compounds in gibberellin₄₊₇ treatment group decreased rapidly,and the content and quantity of esters in brassinolide treatment group increased,but it was still much lower than that in the control group when it was not stored.With the use of compound nitrophenol sodium,the contents of esters and total volatile compounds in pear fruit were between brassinolide and the control group,and the change trend of total volatile matter content in the storage process was consistent with that of the control.（2）The characteristic fragrance of volatile substances in each treatment group was analyzed.Ester,fruity and grassy aromas were the main aroma types.The aroma types and proportions of pome fruits were different under different storage time and treatment methods.Compared with the control,GA increased the aroma of pome fruits during the picking period,while the brassinolide treatment increased the aroma during the storage period.（3）The volatile substances detected in each treatment group during the storage period were subjected to multivariate statistical analysis.The results showed that storage had the greatest influence on the changes of ester content,and the changes in each treatment group were different:GA 4+7 treatment group and rapin lactone treatment group had opposite trends of ester content,while sodium nitrophenolate treatment group and control group had similar trends.In addition,seven key volatile components affecting aroma quality were obtained:hexyl acetate,（3Z）-hex-3-en-1-yl acetate,ethyl acetate,methyl acetate,ethyl butyrate,hexanol and hexanal.These results comprehensively clarified the effects of plant growth regulators on volatile components of pear during storage,and provided important theoretical support for the determination of storage period and production management of pear.