The Preliminary Screening Of Cryoprotectants And Thinning Reagent

In this paper,with branches and pear trees as experimental materials,we mainly study pollen germination and pollen tube growth situation in different temperatures,cryoprotectants of pear,thinning agent of pear.The main results are as follows:1.'Cui Guan' pollen are used as experimental materials,which are treated 4h at different constant temperatures(15 ??20??25??27??30??35 ?)by the way of in vitro culture in order to study the situation of pollen germination rate and pollen tube growth length at different temperatures.The results show that,when the temperature is between 5? to 27 ?,the 'Cuiguan' pollen germination and pollen tube growth length increases with increasing temperature;when the temperature is 27?,the 'Cuiguan' pollen germination and pollen tube growth length reaches the maximum,respectively 67.5%and 235.46?m;then as the temperature rises,the 'Cuiguan'pollen germination and pollen tube growth length is reduced.2.(1)Young fruit were used as experimental materials,to study the effect of cryoprotectants of pear in different periods.The results show that,spraying ?0.2g/L ALA+0.5%KH2PO4 ?0.5 g/L ALA+0.25%KH2PO4 ?300g/L ETH+50mg/L GA3 ?300g/L ETH+0.5%KH2PO4 after full bloom cannot play a good frost effect.Beside,there is a certain correlation between MDA and cold resistance;but activities of SOD?POD and the content of pro-aa have no relation to cold resistance.(2)Studying the effect of different periods of spraying antifreeze,we can see:at the beginingof flower,all reagents are ineffective.When spraying 250 times PBO+0.5%KH2PO4 and 200 times PBO+0.2g·L-1 L-alanine in full flower blossom,these two reagents can reduce the relative conductivity of young fruit,but only can reduce in 8%compared to the control,so in actual production have little effect.When spraying 150 times PBO + 0.5%KH2PO4,200 times PBO + 0.5%KH2PO4 two weeks after full blossom,these two reagents can reduce the relative conductivity of young fruit,but only reducing 4%compared to the control,so in actual production have little effect.(3)Using different concentrations of ALA(0.01g/L,0.05g/L,0.1g/L)and SA(lmmol/L,3mmol/L,6mmol/L)treate pear flower at the beginning of flower.After the cold treatment,we can see from morphology:after treated by 0.01g/L ALA?0.05g/L ALA and 3mmol/L SA,degree of frost of pear flower is lower than the control.The relative conductivity data shows that the relative conductivity of all treatment were lower than the control,but the obvious effect is still O.Olg/L ALA,0.05g/L ALA and 3mmol/L SA.And their relative conductivity were decreased by 7.64%,6.2%,8.99%,which 3mmol/L SA treatment is the best.3.(1)12-year-old trees were used to study the effects of thinning agent of pear in different periods.The results show that,spaying 450 mg·L-1 ETH +5g·L-1 CFA in full bloom,fruit thinning rate is 91.21%,and it does not affect fruit weight,and significantly improves the content of soluble solids and soluble sugar.Besides,it can reduce the total acid content.So it is good for spaying 450 mg·L-1 ETH +5g·L-1 CFA in full bloom.Two weeks after full bloom,only spaying 10g·L-1 CFA+ 7.0 mg·L-1 NAA has effect of thinning fruit,fruit thinning rate is 63.68%.And it has no effect on fruit weight?size?soluble solids and total acid,and the content of soluble sugar of fruit is higher than the contral.So it is more suitable for spraying 10g·L-1 CFA+ 7.0 mg·L-1 NAA two weeks after full bloom.(2)Spraying fruit thinning agents two weeks after full blossom,then placing pear tree in climate chamber of different temperature(25 ? and 30?)to investigate fruit thinning rate.The results show that:the natural fruit thinning rate under 30 ? increases by 22%than 25 ?.As the temperature rises,the fruit thinning rate of 450mg·L-1 ETH+1.5%urea?300mg L-1 ETH+10g · L-1CFA?450mg · L-1 ETH+5g · L-1CFA?450mg·L-1 ETH +25mg·L-1 GA3 are increasing.And compared to 25 ?,the thinning rate were increased by 35%?35%?13%and 25%respectively.But fruit thinning effect of 300mg · L-1 ETH?450mg·L-1 ETH?300mg·L-1 ETH+2%urea?300mg·L-1 ETH + 50mg·L-1 GA3 under 30?are lower than 25?.Fruit thinning rate is reduced by 16%?1%?22%and 16%respectively.And the specific reason remains to be further research.(3)'Beijing White'?'Feng Shui'and 'Huang Jin' were used to screen out more stable thinning agent.The results show that,spaying 400 mg/L ETH+ 50 mg/L GA3 two weeks after full bloom is the most stable.Its fruit thinning rate is more than 50%,and more for single and double fruit inflorescence fruit setting.Besides,it has little effect on fruit quality.So 400 mg/L ETH+ 50 mg/L GA3 meet the requirements of the production of artificial fruit thinning.The statistics on the fruit thinning of 'Beijing White' pear every week found that fruit thinning reaches stable in the forth week.