Responses Of Apple And Red Peeled Pear To Different Chemical Thinners In Kunming Area

In order to knew the effect of different chemical agents on fruit-setting, theproportion of single inflorescence, fruit quality, pollen germination and tube growth andembryo sac development. Using16-year-old Red Fuji apple and8-year-old Red peeledpear as the test material, experiments used cyanamide, urea, thiourea, lime sulfur, TMN-6,CFA and NAA&Eth as the chemical thinning agents for Red Fuji apple and Red Peeledpear. Randomized block design method was used during the blooming stage. According tostudied on the response mechanism of different chemical agents to apple and pear, chosenthe suitable the best concentration of the chemical agent which was obvious, economic,and safe for the apple, pear flower and fruit thinning in Kunming area. The main resultsdemonstrated that:(1) TMN-6’s practicable concentration was0.4%, the dosage and the liquid dosage foreach plant of the16-year-old Red Fuji apple tree were6.69g and1.67L separately. Fruitdropped intensively within2weeks after spraying. The fruit-setting of inflorescence was22.8%investing after physiological fruit drop in2012, the proportion of singleinflorescence was81.02%, and improved the longitudinal, transverse fruit diameter andfruit weight to some extent. It made an effect though burning the petals, anthers and stigma,and killing some part of pollen and restraining the pollen tube growth. And it had noinfluence on the embryo sac development process before pollination.(2) CFA’s efficient spraying time and fruit drop dynamics were the same as TMN-6,its practicable concentration was10g/L. The dosage and the liquid dosage of it for eachplant of the16-year-old Red Fuji apple tree were16.67g and1.67L, respectively. Thefruit-setting of inflorescence was33.8%, the flower-setting of inflorescence was9.57%andthe proportion of single inflorescence was83%. Spraying it, the fruit weight improved, theaverage transverse of fruit increased. There was a certain impact on the internal quality offruit. CFA thinned flower by injuring pollen tube and stigma, but had no effect on thepollen tube which extended into in the lower part of the stigma.(3) Thiourea had an efficient result in Red peeled pear, the effect of thinningdecreased when the concentration of thiourea increasing, and the suitable concentrationwas0.25%, and spraying time was4-5days of central flower in full bloom. The dosage and the liquid dosage for each plant of the8-year-old Red peeled pear tree were1.76g and0.70L separately. The mechanism of it was based on restraining the pollen tube growthwhich was in the upper part of stigma.(4) Spraying lime sulfur, pollen germinated normally on stigma, but it had visiblerestraint to the growth of pollen tube. The effect of thinning was good in Red Fuji applewhen the concentration of lime sulfur was low, but there were two different results indifferent years in Red peeled pear: The effect of thinning was better in high concentrationcompared to low concentration in2011, more obvious than the control. However the effectof thinning was better in low concentration compared to high concentration in2012, andby compared with the fruit-setting rate after treatment by the low concentration lime sulfur,it had no effect of thinning. That means the effect of thinning was varied from differentyears, and the effect was instable too.(5) The varieties of chemical agents used in Red Fuji and Red peeled pear had noinfluence on the embryo sac development process before pollination.(6) From the micrographs of pollen tube growth and embryo observation of the fruitdrop of Red Fuji, it could be observed that there were few pollen tubes in few bottom ofthe stigma in the dropped-fruit of four kind chemical agents. In the embryo in the sameperiod, there existed endosperm nucleus in few ovules, overwhelming majority of theembryos were died early, most embryos stopped growing began from eight-nuclear embryodegradation, only few embryos were belong to embryo abortion.(7) Influenced by florescence disease, the thinning mechanism of urea and NAA&Eth could not show the conclusion from the embryology and the pollen tube growth of Redpear in2012. Its fruit-setting rate had no difference to the control.