Study On The Induction Of Shrivelled-seed Fruit In Longan

1.Five plant growth regulators(PGRs)were sprayed on a normal-seeded cultivar of longan(Dimorcarpus longana Lour.cv.Wulongling)for inducing shriveled-seed fruits. Results showed that the five plant growth regulators all induced some shriveled-seed fruits in certain extent,of which 6-BA and MH were preferable inducers.2.Results showed that MH could induce shrivelled seeds repeatedly,its optimum concentration was 600 mg/L,and its optimum period to spray was 2 weeks after flowering.The content of total soluble solids(TSS),soluble sugar,titratable acid,index of fruit figure,ratio of TSS to acid and sugar to acid all decreased in different extent.The shrivelled-seed fruits quality was promoted with the combination of spraying CPPU. However,6-BA didn't induce shrivelled seeds repeatedly,which needed further study. Index of fruit figure proved to be good measure to value whether the fruit of longan was seedless.3.To establish a high performance liquid chromatography(HPLC)to determine the content of endogenous hormones,including GA₃,IAA and ABA.Potyvinyl polypyrrolidone(PVPP) and phosphate buffer solution(PBS)were applied successfully to remove the impurities with the sound retention time and repeat.The mobile phase was CH₃CN-H₂O(25:75,V/V)for GA₃,and CH₃CN-H₂O(15:85,V/V)for IAA and ABA. The flow rate was 0.8ml/min.Injection volume was 10μl.The temperature of the column was set at 30℃.And the wavelength was 210nm.It was proved that this procedure was simple,rapid and accurate for efficient determination of endogenous hormones in longan samples.4.Results showed that formation of the seed in longan(Dimorcarpus longana Lour. cv.Wulongling)was about in the late June.Growth curve of the fruit in the control group was double 'S',as a result of the increase of seed and flesh respectively.However, development of the shrivelled seeds induced by MH was restrained so that the curve grew single 'S'.The transformation might be correlated with the changes of their endogenous hormones.5.Results showed that the content of GA₃,IAA and ABA in shrivelled seed decreased clearly in the fruit development.The content of GA₃ reached the bottom in the maturation,while 2 weeks before maturation the content of IAA and ABA rose slightly. The trend of the content of GA₃ and IAA in the control group accorded with the development of the fruit weight,whereas the content of ABA decreased continuously.It was proved that the content of GA₃ was low in shriveled seed,which was adverse for the development of fruit.Treatment with MH was closely correlated with the low content of GA₃ and high content of ABA.Consequently,the seedless fruit weight was low and its quality was poor.6.During the period of seed formation(from June 22 to July 8),ABA/GA₃ and IAA/GA₃ in seedless fruit were remarkably higher than the control,and ABA/IAA was also higher on July 8,which was the main reason why the normal seed of longan became shrivelled.Moreover,high level of ABA/GA₃ was adverse for the fruit development of longan,and low level of ABA/IAA and IAA/GA₃ were favorable for the development.