Effect Of Sucrose On Affinity Reaction Of Cucumber/Pumpkin Grafting

Cucumber(Cucumis sativus L.)is one of the most important vegetable crops cultivated in China.Its root system is weak,salt tolerance is weak,cold resistance is poor,and grafting technique is often used to achieve high quality cucumber cultivation.The premise of realizing the goal of cucumber grafting is the affinity between stock and scion.If the grafting is not compatible or weak,the grafted seedling will fail to survive or the survival rate is very low.Even if the grafting survives,it will show the phenomenon of poor growth or failure to grow,which will cause great losses to production.At present,the studies on grafting affinity at home and abroad are mostly focused on fruit trees,and there are few reports on vegetables.Differences in this study two affinity of pumpkin(Cucurbita moschata Duch)varieties ‘Heizi Pumpkin(affinity)’ and ‘Dongyangshenli(no affinity)’,in three different growth of cucumber varieties ‘Shenluschunsi(growing)’,‘Cuilv Cucumber(weak)’ and ‘Liangyoulvjian 102(medium)’ as a scion,analysis the root stock/scion grafting affinity,By measuring the root stock and scion stem cut surface exudates soluble sugar,sucrose content and the grafting healing surface resistance,graft survival rate and key enzyme activity,sucrose synthesis research rootstock and scion stem cut surface oozy liquefaction learn composition and the relationship between the grafting affinity,further explore the effects of exogenous sugar on grafting affinity,trying to seek a method to improve cucumber/pumpkin grafting affinity.The main research results are as follows:1.Rootstock variety is the decisive factor of grafting affinity of cucumber/pumpkin.With two affinity of pumpkin varieties ‘Heizi Pumpkin(affinity)’ and ‘Dongyangshenli(no affinity)’,in three different growth of cucumber varieties ‘Shenluschunsi(growing)’,‘Cuilv Cucumber(weak)’ and ‘Liangyoulvjian 102(medium)’ as a scion,composed of six kinds of grafting combination,by analyzing the survival rate of grafting,healing the surface resistivity,It was found that the effect of stock/scion combination on grafting affinity mainly depended on stock variety,but had little relationship with scion variety.2.There was a negative correlation between sucrose content difference and affinity in the exudate of cut surface between anvil and ear.Anvil correlation between soluble sugar content is the most important the influence of difference of grafting affinity,grafting affinity between the anvil spike and stem cut surface exudates soluble sugar content in the difference between absolute value was significantly negative relationship,when the anvil correlation between the closer the sucrose content in the stem cut surface exudate,the grafting survival rate is higher,the stronger the affinity,or conversely;However,there was no significant correlation between p H value,EC value,free amino acid content,soluble protein content,organic acid content and grafting survival rate.3.Sucrose synthesis ability of pumpkin rootstock stems determines grafting compatibility by influencing sucrose content in exudate.To explore causes two pumpkin root stock varieties of sucrose content in the stem cut surface exudate significant difference,the pumpkin root stock stem of sucrose phosphate synthase(SPS),sucrose synthase(SS),acid invertase(AI)and neutral invertase(NI)four key sucrose metabolism enzyme activity and its coding gene expression level were analyzed.The results showed that the activities of SPS,SS and NI of the incompatible rootstock ‘Dongyangshenli’ were significantly higher than those of the compatible rootstock ‘Heizi Pumpkin’,but the activities of AI were significantly lower than the latter.Similarly,the relative transcription level of SPS encoding gene CP4.1LG04G09100,SS encoding gene CP4.1LG04G11350 and NI encoding gene CP4.1LG04G05130 in rootstock ‘Dongyangshenli’ was also significantly higher than that in rootstock ‘Heizi Pumpkin’,while the relative transcription level of SS encoding gene CP4.1LG18G02810 in rootstock ‘Dongyangshenli’ was significantly lower than that in rootstock ‘Heizi Pumpkin’.These results indicated that the sucrose synthesis ability of the incompatible rootstock ‘Dongyangshenli’ was significantly higher than that of the compatible rootstock ‘Heizi Pumpkin’,leading to the accumulation of sucrose content in the stem,which further resulted in a large difference in sucrose content between the rootstock and the scion in the exudate on the cut surface of the stem,and finally resulted in grafting incompatibility.4.Exogenous sucrose treatment could significantly improve the grafting affinity of cucumber/pumpkin.In order to confirm the conclusion that the difference of sucrose content in the exudate between rootstock and scion stem cut surface was negatively correlated with the affinity,the sucrose content in the exudate between rootstock and scion stem cut surface was significantly increased,the difference of sucrose content between rootstock and scion was decreased,and the grafting survival rate was significantly increased by spraying scion plants with exogenous sucrose.Through continuous measurement of the resistance of grafted grafts healing surface,it was found that the resistance changes of grafted healing surface after exogenous spraying of sucrose at 5 ‰and 10 ‰ concentrations were the same as those of grafted affinity plants.These results indicate that treating scion plants with exogenous sucrose to reduce the difference of sucrose content between rootstock and scion in the exuviate is an effective method to improve the affinity of cucumber/pumpkin grafted seedlings.In conclusion,this study found that the effect of stock/scion combination on grafting affinity mainly depended on stock variety,but had little relationship with scion variety.The results revealed the role of sucrose in the grafting affinity reaction of cucumber/pumpkin,that is,the closer the sucrose content in the exude of the cut surface between the anvil and ear,the higher the grafting survival rate and the stronger the grafting affinity.The application of 5 ‰ and 10 ‰ sucrose solution on scion could significantly increase the sucrose content in the exuvial solution on the cut surface of scion stem,reduce the sucrose content difference between the anvil and ear,and significantly improve the survival rate and compatibility of grafting.This study provided an effective method to improve the grafting affinity of cucumber/pumpkin.