| kiwifruit is a kind of fruit which is typical climacteric and extremely sensitive to ethylene,chilling injury is prone to occurr in the cultivar of Actinidia chinensis than that of Actinidia deliciosa,kiwifruit treated with 1-MCP are difficult to soften in shelf life.The best indicator of controlled atmosphere storage(CA)of the cultivars 'Huayou' and'Hongyang' of Actinidia chinensis was studied,and the quality and physiological indicators during storage period and shelf life of the two cultivars were investigated.'Huayou' is a natural hybrid of Actinidia chinensis and Actinidia deliciosa.Yellow flesh is the consequences of normal development.Recently,there is a severe problem that the flesh cannot degreen normally after storage,causing its commodity value affected seriously.In this paper,effects of harvest time and storage temperature on flesh color and expression of chlorophyll degradation enzyme gene of 'Huayou' were studied.The results are as follows:1.Firmness and quality of 'Huayou' and 'Hongyang' during storage period were fairly maintained by all the treatments of CA1(2.5%?%O2+3%?3.5%CO2),CA2(2.5%?3%02+3.5%y4%CO2)and CA3(2.5%?3%02+4%?4.5%C02),and effect of CA3(2.5%?3%O2+4%?4.5%CO2)was the best.Firmness and SSC of 'Huayou' treated with CA3 were 5.4 kg/cm2 and 13.8%when stored at 138th day,whereas the figures of CK were 1.6 kg/cm2 and 14.8%,respectively.Firmness and SSC of 'Hongyang' treated with CA3 were 1.6 kg/cm2 and 14.8%when stored at 145th day,while those of CK were 0.9 kg/cm2 and 15.3%,respectively.Hence,the indicator of C.3 was chosen as the optimal parameter for controlled atmosphere of'Huayou' and 'Hongyang' kiwifruit.2.Firmness of 'Huayou' treated with CA3 was dramaticlly higher than that of CK within the shelf life of 5 days after New Year's day and Spring Festival.However,it didn't occurred remarkable difference between CA3 and CK during later shelf life.It indicates that 'Huayou' treated with CA3 could soften fast during shelf life.SSC was significantly inhibited by CA3 during shelf life of New Year's day,but that of Spring Festival was not significant inhibited.3.Firmness of 'Hongyang' during shelf life of early stage of storage(56 days)was significantly inhibited by CA3,however,it didn't occurred remarkable differencebetween CA3 and CK during shelf life of later stage of storage.Firmness of kiwifruit treated with 1-MCP is significantly higher than that of CK,so it indicates that kiwifruit treated with CA3 could soften normally during shelf life compared with that treated with 1-MCP,The SSC of cold storage,1-MCP and CA3 had no significant difference during shelf life of 7 days.Research on the quality of 'Hongyang' during shelf life of one month,New Year's day and Spring Festival shows:firmness of kiwifruit treated with CA3 is higher than that of CK but had no significant difference,However,firmness of kiwifruit treated with 1-MCP is significantly higher than that of control,Further shows that kiwifruit treated with CA3 can soften normally during shelf life;The SSC had no significant difference during shelf life under three kinds of treatment.4.The respiration and ethylene release rate of 'Huayou' and 'Hongyang' were significantly inhibited by CA3 during shelf life of New Year's day and Spring Festival.The ethylene release rate of CA3 was higher than that of 1-MCP during later shelf life of New Year's day in 'Hongyang',consistent with the changes of firmness.5.The decay of 'Huayou' and 'Hongyang' was significantly delayed and the rotting rate was significantly decreased by CA3 during storage period,and the rotting rate was reduced by 6.2%and 37%respectively than CK.The rotting rate of 'Hongyang'during shelf life of New Year's day was also reduced by 8.2%.6.Fesh color turned from green to yellow and hue angle(h*)decreased significantly along with the harvest time and shelf life.Fruit harvested at 134-141 days after full bloom(flesh hue angle range from 110.04° to106.89°,SSC range from 5.9%to 6.9%)could turn yellow(h*<103)during shelf life of 14 days,and kept proper firmness,maintaining a longer shelf life.Fruit firmness and flesh hue angle had no significant correlation along with the harvest life,while SSC and flesh hue angle had extremely significant negative correlation(the correlation coefficient was-0.943,P<0.01).7.The flesh chlorophyll content was reduced significantly along with the harvest and shelf life,whereas content of carotenoids had no significant change.The ratio of carotenoid and chlorophyll content increased significantly and it is negatively related to the changes of hue angle(h*)significantly,flesh could turned yellow only when the ratio is above 0.8.8.The relative expression of SGR2 gene was significantly increased(113DAFB to 148 DAFB)and then declined(155 DAFB)along with the harvest periods.Expression quantities of SGR2 was the highest when picked on 148 DAFB and it occurred significant differences in different harvest time,it had greater range(1?9.14)compared with PPH1,CBR2 and PAO1.The relative expression of PPH1 gene had a increasing trend along with the harvest periods,and it changed in the range of 1-3.79.The expressions of SGR2 and PPH1 were dramaticlly negatively correlated with the hue angle(h*)in different harvest period(the correlation coefficients were-0.819 and-0.810,respectively).The expressions of SGR2 and PPH1 had a highly significant positive correlation(the correlation coefficient=0.883,P<0.01).Therefore,it is likely that SGR2 and PPH1 are the key regulatory factors in chlorophyll degradation of 'Huayou'kiwifruit.9.This research indicated that the relative expression of CBR2 had no significant difference,it had no significant correlation with the change of hue angle(h*)and it changed in the range of 1?.7.The expression of PAO1 was stable,and it also had no significant correlation with hue angle(h*).Therefore,they may not have the key regulatory effect on chlorophyll degradation of 'Huayou' kiwifruit.10.Storage temperature is the key factor of chlorophyll degradation.Chilling injury of 'Huayou'was increased when stored at-0.5±0.3 ?,rate of ethylene and respiration were also increased,SSC is relatively low and flesh cannot degreen normally in shelf life.Chlorophyll content of flesh stored at-0.5±0.3? was significantly higher than that of 0.5±0.3 ?.Therefore,the storage temperature of yellow flesh kiwifruit in the production should be controlled appropriately. |
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