Effects of Exogenous GA3 on Cold Resistance of Korla Fragrant Pear

In this experiment, the Korla Pear plant with strong tree vigor, and normal fruit was used as test materials to survey the freezing resistance. In leaf stage (May 6, 2013 ), different concentrations of exogenous GA3 (50, 75, 100 mg/L ) were sprayed once every 20 days, for three times. In the period of dormancy, the Korla Pear plant branches were collected. And the hardiness index, such as conductivity, MDA, proline, soluble protein, soluble sugar and starch content were surveyed and the degree of membership of each composite indicator was evaluated under artificial low temperature conditions. The results show that: with 100 mg/L GA3 once processed, the average membership is more than 0.7, which is high resistance; the average membership of the treatments of 50 mg/L GA3 once, 75 mg/L GA3 once, 50 mg/L GA3 twice, 75 mg/L GA3 twice, 100 mg/L GA3 twice and 100 mg/L GA3 for three times are all more than 0.4, which are middle resistance; the average membership of the treatments of both 50 and 75 mg/L GA3 for three times are more than 0.3, which are lower resistance. This result shows that the best spraying GA3 concentration is 100 mg/L, treatment time is once, and it can resist low temperature at −24˚C. But to determine the optimal spraying time and concentrations of exogenous hormone needs further study.