Effectiveness of Ethephon for Inducing Deblossoming of Mango cv. Nam Dok Mai

Abstract

Hand deblossoming can be a time consuming process for farmers who grow mangoes for commerce.  In order to save on the labor used in hand deblossoming, ethephon, a plant growth regulator releasing agents of ethylene, has become another option to induce deblossoming in mangoes today. This study aimed to evaluate the effectiveness of ethephon in various concentration levels on the deblossoming of mangoes and the effect of ethephon on the mango’s inflorescences reproduction. This experiment was conducted at a farmer’s orchard in Mae Taeng, Chiang Mai on mango trees cv. Nam Dok Mai that were 6 years old. The trial was laid out in completely randomized design with 4 treatments: hand deblossoming and spraying 3 various levels of ethephon at a concentration of 400, 600 and 800 ppm respectively during full bloom. Deblossoming of the inflorescences and reproduction of the mangoes inflorescences were observed from December 2006 until June 2007. 

The average number of the growing tips in the field trial was 347.5 shoots per tree. According to the number of apical meristems being experimented in the field, the tree could produce inflorescences at a percentage of 74.08. The result showed that after ethephon sprays were applied at a concentration level of 600 ppm on the inflorescences, the deblossoming of inflorescences was the highest at 99.1  percent, similar to hand deblossoming. The whole inflorescences were shed naturally from the shoot within 19.7 days after the ethephon sprays were applied and it took the shortest time. After the first flower set was removed, the tree reproduced a second flower set in the same site as well as in new sites.  It took 41.8, 21.3, 27.4 and 35.9 days for the tree to reproduce a second flower set in the same sites by hand deblossoming and spraying 3 various levels of  ethephon respectively. However, the total number of inflorescences from the second flower set was less than the first flower set at the percentage of 52.5, 61.3, 45.9 and 40.3 respectively. The panicle size of the second flower set was smaller than the first flower set. The total number of floret per inflorescence also showed no differences statistically among treatments which accounted for 565.7, 373.0, 372.0 and 442.3 respectively. The number of perfect flowers was at percentages of 65.5, 70.3, 73.5 and 47.5 respectively. From the result, ethephon sprays applied during full bloom at a concentration of 600 ppm can be used effectively on mangoes instead of hand deblossoming.