Changes Of Physiological And Biochemical Indexes And Secondary Metabolites In Actinidia Kolomikta Fruits During Development And Ripening

Actinidia kolomikta has strong stress resistance,is one of the most cold-resistant kiwifruit varieties,and has nutritional value and health care effects,for this reason it has been paid attention to and recognized by people.In order to master the fruit development law of Actinidia kolomikta,we used wild Actinidia kolomikta as experimental materials,and measured the changes of cell wall components,activities of cell wall degrading enzymes,activities of antioxidant enzymes and contents of secondary metabolites during fruit development,so as to accumulate basic data for standardized cultivation in the future.The experimental results are as follows:(1)The single fruit weight of Actinidia kolomikta showed a fast-slow-fast growth trend;The firmness of fruit increased significantly and decreased significantly after reaching the peak value on 43 d.The fruit shape gradually approaches to a circle.The content of soluble solids increased gradually,and the content of titratable acid increased significantly to the peak on 57 d,and then decreased significantly in the softening stage.The contents of total sugar,soluble sugar and reducing sugar increased rapidly from 43 d to the maximum in softened fruits,while the contents of starch and VC increased in a wave form,and then decreased sharply with the softening of fruits after reaching the maximum on 57 d.(2)The total pectin content of Actinidia kolomikta fruit decreased slowly,but the soluble pectin content increased significantly in the softening stage.The change trend of cellulose and hemicellulose content was opposite from 15 d to 43 d,after the cellulose content did not change significantly,but the hemicellulose content decreased significantly.(3)The activities of PG,Cx,β-Gal and PME in Actinidia kolomikta fruit decreased slowly or remained stable in the middle and early stage of fruit growth and development,and the enzyme activities increased significantly during fruit softening.The activity of β-amylase increased significantly in the softening stage,which played an important role in fruit softening.(4)The activities of SOD and PPO in Actinidia kolomikta fruit increased in waves;POD activity decreased in waves;CAT activity decreased significantly after reaching its peak on 57 d.The content of MDA increased significantly during softening.(5)The polysaccharide content of Actinidia kolomikta fruit increased continuously;The contents of total phenol,total flavonoid and alkaloid decreased slowly,forming a small peak on 57 d,and decreased significantly during fruit softening.