Study On Residues Of Gibberellic Acid In Cucumber

In recent years, the media hype the "hormone cucumber" such as "cucumber with flower and spines", "the pill cucumber", causing public panic to plant growth regulator, gibberellic acid as plant growth regulator is commonly used in cucumber, but previous research has not been reported its residue in cucumber, in addition, still can use NAA, paclobutrazol, thidiazuron and forchlorfenuron on cucumber.In order to master the residual pollution condition and degradation rule of plant growth regulator, reduce unnecessary panic of the public to plant growth regulator.This paper validated the influence of gibberellic acid on cucumber quality and growth, established the multi-residue determination method of gibberellin, NAA, paclobutrazol, forchlorfenuron and thidiazuron and optimization of gibberellic acid residues detection method, detect the residue of gibberellic acid in cucumber, the goal is to proven residual conditions and the degradation rule of gibberellic acid on cucumber, provide data support for the development of domestic residue limits standard, guarantees the public food safety.,the main contents and results are as follows:(1) Studied the effects of gibberellic acid on cucumber quality and growth.In the cucumber fiied which used plastic green house, choose 25 mg/kg and 50 mg/kg of gibberellic acid spraying cucumber female flowers, compared with the CK contrast treatment, all can highly significantly reduce the total acid content in the mature period of cucumber fruit;has no impact on the soluble solids content in fruit;can significantly increased the weight of the cucumber fruits;can highly significantly increased the length of the cucumber fruits;using 25 mg/kg gibberellin spraying cucumber female flowers can significantly improve the vitamin C content in cucumber fruits, but when using 50 mg/kg gibberellin spraying cucumber female flowers compared with the CK contrast treatment, vitamin C content in fruit was very significant decline.In cucumber storage link, between 0-15 days after using 10 mg/kg gibberellic acid solution soaking the cucumber, the soluble solids content tend to rise, increased the total acid content, but was reduce the content of vitamin C.(2) Established the multi-residue determination method of gibberellic acid, NAA,paclobutrazol, forchlorfenuron and thidiazuron.Detection limits were 0.002mg/kg, 0.05mg/kg,0.00005mg/kg,0.00001 mg/kg,0.0002mg/kg, respectively.Good line relationship were shown for gibberellic acid and NAA in the range of 0.002-0.5mg/kg, and good linear relationship were shown for paclobutrazol, forchlorfenuron and thidiazuron in the range of 0.0004-0.1 mg/kg, both of the correlation coefficients were bigger than 0.99. At 0.05 mg/kg and 0.1 mg/kg added level,the recovery of gibberellic acid was 99.53%～116.35%,the recovery of NAA was 88.48%-112.63%. At 0.01 mg/kg and 0.02 mg/kg added level,the recovery of paclobutrazol, forchlorfenuron and thidiazuron were 69.07%～76.05%,73.41%-81.41%,73.67%-82.89%, respectively. All of these five plant growth regulators, the relative standard deviation were from 0.96%-8.25%.(3) Improvement the residue determination method of gibberellic acid on the cucumber.Nice linear relationship was shown for gibberellic acid in the range of 0.0002～0.1mg/kg,the correlation coefficients equal 1.At 0.01 mg/kg,0.02 mg/kg and 0.1 mg/kg added level,the recovery was in the range of 85.72%～114.67%, relative standard deviation (RSD) is between 1.43% to 8.38%.(4) Studied the residue degradation dynamics of gibberellic acid on cucumber. Experiment in the field which used plastic green house show that, when using gibberellic acid which concentration was 25 mg/kg and 50 mg/kg spraying flowers on cucumber, the original deposit amount were 2.70 mg/kg and 4.83 mg/kg,the half-life of gibberellic acid residue on cucumber was 1.37 days and 1.54 days,respectively., and after 9 days were 0.02 mg/kg and 0.07 mg/kg,it’s lower to the maximum residue limits of gibberellic acid on cucumber in Japan(0.2 mg/kg).Experimental in storage period, when using gibberellic acid which concentration was 10 mg/kg and 100 mg/kg after soaking cucumber,the original deposit amount were 0.06 mg/kg and 0.32 mg/kg, the half-life of gibberellic acid residue on cucumber was 8.71 days and 29.05 days, respectively, the residual values of 10 mg/kg treatment always lower than MRLs in Japan,after 15 days the residual values of 100 mg/kg treatment was still higher than MRLs in Japan.