Effects Of Cyanamide On Physiological Characteristics Of Dormancy Release And Comprehensive Quality Of Different Grape

Dormancy is an insurmountable stage for the growth and development of deciduous fruit trees,such as grapes.It needs a certain amount of cold to achieve normal growth and development.Therefore,lifting the natural dormancy and promoting early germination has become a key technology to be solved in the grape cultivation in greenhouse.In this experiment,three grape cultivars ’Zaoheibao’,’Zaoxia Meigui’ and’Shaoxing No.1’ were selected as test materials and treated with sleeping breaking agent（H₂CN₂）and water as control（CK）.The changes of climate factors,phenological periods and the growth of new buds,leaves and fruits were recorded during the dormancy breaking period.The microstructure of winter buds was observed by paraffin section technology,and the related physiological and biochemical indexes such as agronomic traits,bud enzyme activity,photosynthetic pigment content in leaves and fruit appearance and internal quality were determined Combined with the principal component analysis and comprehensive evaluation index,the comprehensive analysis was carried out to explore the effect of monocyandiamide treatment on the growth and development of different grapes and reveal the main influencing factors of breaking dormancy of grapes.The main results as follows:1.The germination and fruit ripening stages of all grapes were significantly advanced by the treatment of H₂CN₂.The grape ’Zaoxia Meigui’ sprouted the earliest,followed by ’Shaoxing No.1’,and finally ’Zaoheibao’,which were 34,37 and 32 days earlier than the control,respectively.The grapes grew rapidly to about 20 days,completed the germination period,and appeared 3～4 new leaves,which showed a trend of slow first and then fast,and the germination uniformity was similar to that of the control The germination rate increased significantly.2.After dormancy breaking treatment,the internal structure of each grape bud developed rapidly,the growth point gradually increased and elongated,the main axis differentiated and filled with buds,the number of cells increased,the leaf primordium formed continuously,the inflorescence primordium developed continuously,and the flower meristem morphology was complete;but after water treatment,the internal growth of bud was slow,the structures developed but did not take shape,and a small amount of leaf primordium and inflorescence could be seen There was no significant change in the whole primordium.3.The content of H₂O₂ and POD activity of all grape buds were significantly higher than those of the control,while the activity of cat was significantly decreased;the content of chlorophyll b,total chlorophyll and carotenoid in leaves were significantly increased at maturity stage;there was no significant difference in fruit external quality between the two treatments,and the internal quality indexes such as soluble sugar,soluble protein,Vc and titratable acid were higher in ’Zaoheibao’ and ’Shaoxing No.1’.However,there was no significant difference in ’Zaoxia Meigui’.4.Principal component analysis（PCA）of 33 physiological and biochemical indexes showed that germination uniformity,germination rate,H2O2 Content,POD activity and CAT activity were the main factors affecting the release of grape dormancy.5.The results showed that the comprehensive quality of grape was classified as ’Zaoheibao’（H₂CN₂）>’Shaoxing No.1’（H₂CN₂）>’Zaoheibao’（CK）>’Zaoxia Meigui’（H₂CN₂）>’Shaoxing No.1’（CK）>’Zaoxia Meigui’（CK）.