| According to the problem of producing spot and pesticide residue of muskmelon fruitsurface caused by using insecticides or fungicides improperly, thus affecting the fruitmarket price, taking the way of using pesticides correctly and isolating the pollution mode,take over light color muskmelon “Jiu Hongrui” as test materials, the surface of the youngmelon were sprayed on with mixed liquor of14fungicides or5insecticides separately withadditives "three siloxane". After7d of sprayed, chlorophyll fluorescence parameters weremeasured on the fruit surface, and toxic effects of pesticides were analyzed on melonsurface. At the same time, studies on the effect of materials and bag types on fruit qualityand chlorophyll fluorescence parameters of fruit surface after bagging7kinds of differentmaterials and13kinds of bag types in melon fruit period. The main results are as fellows:1、 Spraying alone with organochlorine pesticides， the effect of chlorophyllfluorescence parameters of melon surface, was not obvious in comparison with control，after spraying2kinds of organochlorine pesticides and additive, it decreased ABS、Fo、Fmand Fv/Fm of fruit surface,while significantly reduced Y(Ⅱ), moreover, significantlyincreased the fruit surface Y (NPQ) and Y(NO).2、 Spraying alone with various fungicides or insecticides, or additives, spotssymptoms did not occur, and the effect of PIS, synthetic poison index of chlorophyllfluorescence parameters of melon surface, was not obvious in comparison with control.But spraying with mixed liquor of various fungicides or insecticides separately withadditives, spot symptom was very obvious with characteristics of scattered non-uniformdistribution, and its PIS also increased significantly in comparison with control. PIS wasobviously higher at the15d after flowering treatment than at the8d after flowering, andPIS of the treatment of2times conventional concentration increased slightly. Also, PIS onspots area is significantly higher than on non-spot area on fruit surface. It shows bycomprehensive analysis above that the fruit surface injury spots occurred primarily inrelationship with the good wetting, spreader and permeability of additives "three siloxane".The poison characteristics on photosystemⅡ (PSⅡ) dynamic activity shows multiple sitesby fungicides and insecticides, such as not only the PIS of light absorption (ABS),absorption (ABS), antenna capture capability (Fm) and primary photochemical capacity(Fv/Fm) of PSⅡincreased significantly; but also the PIS of the actual quantum yield Y (Ⅱ) of PSⅡ also increased significantly, which suggest that activity of carbon absorptionkinetics was also affected; anymore, PIS of Y (NPQ) and Y (NO) increased significantly,which suggest that is excess energy dissipation, that may cause photoinhibition or lightdamage of PSⅡ and even the entire photosynthetic apparatus, and may lead to thermalburn spots of organization on fruit surface.3、Bagging in melon fruit period can reduce the number of spots and fruit scar causedby farm working, can protect from pesticide and pests’ feces, can made the skin clean andglossy,and so improve remarkably the appearance quality. Different materials and typesbags had no obvious effect on pulp thickness and fruit shape index.4、Effect of bagging on temperature and condensation amount. The temperature insidethe bag approached to the control temperature with holes in bag surface, bag materials andtypes played a significant role in condensation amount, among them, the condensationamount of GF and RF was the largest, PF was the least; the condensation amount of thetype of two kinds of bags without holes and pockets was the largest, the type of2pairs ofholes、4pairs of holes and6pairs of holes was larger, the type of top opening、bottomopening and top opening+bottom opening is the least.5、Effect of bagging on fruit growth. Bagging early, fruit grew rapidly, fruit weightand perimeter increased significantly, fruit grew slowly after bagging21and28days. Inharvest time, fruit weight of EF was significantly higher than that of CK15.9%, GFreduced by11.32%compared with CK, other treatments had no significant difference withCK. There was no significant difference on fruit perimeter among each treatment. The fruitperimeter of GF was bigger, and RF was the least in the growth circle. The treatments ofbag type were significantly increased fruit weight and perimeter of harvest time, the typeof doliform with2pairs of holes had biggest fruit weight and perimeter,41.7%and9.9%higher than that of CK respectively.6、Effect of bagging on nutritional quality. The content of VCwas higher than that ofCK after bagging7kinds of materials bags, BF had the highest content of VCin fruit,61.5%higher than that of CK respectively; the content of soluble sugar of PF is the highest,with14.5%higher than that of CK, the content of soluble protein of RF is the highest, with51.6%higher than that of CK. Different bag types had different influence on nutritionalquality. Among them, the type of flat with top opening+bottom opening had the highestcontent of VC,19.4%higher than that of CK, the type of doliform with6pairs of holeswas the least, and VCcontent of the type of flat was higher than that of the type of doliform;the type of bottom opening had the highest content of soluble sugar,23.3%higher thanthat of CK; the type of flat with6pairs of holes had the highest content of soluble protein,content of soluble protein of the type of doliform with6pairs of holes was significantlylower than CK, it reduced31.03%than that of CK. Bag materials and types had nosignificant effect on soluble solids content. 7、Effect of bag materials on the fruit surface chlorophyll fluorescence parameters andthe influence of light energy utilization. Whether bagging or not, as the fruit growth, thelight absorption of fruit surface was gradually reduced, the maximal photochemicalefficiency of PSⅡ in the dark of fruit surface had no significantly change in first21days,quantum yield of regulated energy dissipation and quantum yield of non-regulated energydissipation of fruit surface were gradually reduced, but actual light quantum yield of PSⅡwas gradually increasing, but ABS、Fv/Fm、Y (NPQ) and Y (Ⅱ) suddenly dropped to0atripe time，Y (NO) suddenly rised to1; at the same time, the fruit surface energy utilizationafter bagging with7kinds of material bags was significantly lower than CK.8、Effect of bag materials on the fruit surface chlorophyll fluorescence parameters.Whether bagging or not, as the fruit growth, Fv/Fm gradually reduced, Y (Ⅱ) increasedfirst and then decreased, Y (NPQ) gradually reduced, Y (NO) showed a slow increasingtrend, but Fv/Fm、Y (NPQ) and Y (Ⅱ) suddenly dropped to0at ripe time，Y (NO) suddenlyrised to1. |
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