Effect Of Plant Growth Regulators On Sweet Cherry Fruit Setting And Fruit Quality In Shanghai

Sweet cherry production was rapidly increasing during the past 10years since the huge market demand in the world.The regions of sweet cherry production has spread to west and south china,including Shanghai.However,the low fruit set limited the production of sweet cherry in south china,since the inadequate low chilling requirement in warm regions.To improve fruit production,plant growth regulators（PGRs）were selected to investigate effects on fruit set and fruit quality.PGRs can regulate the physiological processes such as flowering,dormancy,growth and germination.PGRs are often used to increase the fruit set,yield and quality of the crop.The object of this research is to investigate the effect of PGRs on fruit set,fruit quality and postharvest quality of two sweet cherries cv.’Royal Lee’and’U810’.Research results obtained are as follows:1.Effect of different PGRs on fruit set of cv.Royal Lee and U810.The PGRs treatments can significantly improve fruit set.Among the 7treatments,fruit set of group GA₄₊₇+NAA+6-BA is the highest,which is up to 23.4%and 52.8%of Royal Lee and U810 in separate;fruit set of group GA₄₊₇+NAA,GA₄₊₇+6-BA and NAA+6-BA are 8.3%,5.5%,3.6%and 36.8%,10.2%,8.1%of Royal Lee and U810 in separate;fruit set of group GA₄₊₇,NAA and 6-BA are 4.7%,3.1%,0.6%and 9.8%,7.7%,2.4%of Royal Lee and U810 in separate.In contrast,the fruit set of the control group is only 0.6%and 2.5%.2.Effect of different PGRs on fruit development of cv.Royal Lee and U810.PGRs can promote cell division of fruit in the early stage of fruit growth,among these treatments,the impact of group GA₄₊₇+NAA+6-BA and GA₄₊₇+6-BA are the most apparent.Some treatments,such as GA₄₊₇+NAA+6-BA and GA₄₊₇+NAA also have effective on cell expansion at the late stage of fruit development in sweet cherries.Cell division of fruit is closely to 6-BA and fruit cell expansion is significant effected by GA_4+7.The growth rate of fruit longitudinal and transverse diameters in the control group is faster than that in the treatment groups during the early stage of fruit growth,since the treatment groups are in a state of rapid cell division,and this division have negative effect on cell expansion.However when it comes to late fruit growth stage,the growth rate of treatment groups exceed the control group.3.Effect of different PGRs on fruit quality and postharvest quality of cv.Royal Lee and U810.The combination of GA₄₊₇+7 and 6-BA or separated treatments increase the fruit firmness and delay the decline of fruit hardness.The PGRs treatments,such as GA₄₊₇+NAA+6-BA and GA₄₊₇+NAA,can delay the fruit ripening time,and decrease soluble solids content of cherry fruits slightly.The application of PGRs in sweet cherries can improve fruit set,promote cell division and fruit enlargement,increase fruit firmness,delay fruit maturation and increase fruit shelf life after harvest.The combination of GA₄₊₇+NAA+6-BA treatment resulted in the highest fruit setting rate and larger size fruit in comparison with other treatments.In addition,GA₄₊₇+6-BA has a significant effect on improving fruit firmness.