Effect of Plant Growth Regulator GA 3 on Alkaloid Content in Upper Leaf of Flue-cured Tobacco

The effect of GA3(Gibberellic Acid: C19H22O6) on the alkaloid content and composition in upper leaf was investigated with Yunyan 87 as experimental material,the results showed that: 1) the contents of total alkaloid,nicotine,nornicotine,anatabine and anabasine significantly decreased by GA3 spraying at the concentration of 1.5×10-5-3.5×10-5;2) the contents of total alkaloid,nicotine,nornicotine,anatabine and anabasine were significantly negatively correlated with GA3 concentration in the range of 0 to 3.5×10-5,the confidence level for anabasine was P0.05 and for the others was P0.01;3) with the increase of GA3 concentration in the range of 0 to 35×10-5,the percentage of nicotine in total alkaloid increased,while the percentages of nornicotine,anatabine and total microalkaloid decreased,and the percentage of anabasine changed little;4) in the range of 0 to 3.5×10-5,the confidence level of correlation between the percentage of nicotine or total microalkaloid in total alkaloid and GA3 concentration was P0.01,and that of nornicotine or anatabine was P0.05.The irritancy of upper leaf of flue-cured tobacco could be significantly weakened by GA3 spraying at suitable concentration,and it was of benefit to the leaf quality.