Effect of combined application of CPPU and GA3 on the growth of 'Irwin' mango fruits.
Sasaki K., Utsunomiya N.
Author Affiliation: Experimental Farm of Kinki University, Yuasa, Wakayama 643-0004, Japan.
Japanese Journal of Tropical Agriculture 46 : 224-229
Abstract : The effect of the combined application of solutions of CPPU [forchlorfenuron] and GA3 on the fruit growth of 'Irwin' mangoes was investigated during 1996 and 1997, in Wakayama, Japan. Two applications of 10 or 20 ppm CPPU plus 100 ppm GA3 to whole panicles from the full bloom stage caused abnormal fruit growth, and no fruit set could be obtained. When the same treatments were applied from the end of the flowering time, fruit growth was not appreciably affected and the total soluble solids of the fruits decreased. Spraying of 10 ppm CPPU plus 100 ppm GA3 to panicles twice and 4 times from the end of the physiological fruit drop stage promoted fruit growth. The effect was more pronounced with 4 applications than with 2 applications. Total yield per tree increased because of the increase in the average weight of both seeded and seedless fruits, and the number of harvested seedless fruits increased with 4 applications. The ratio of bigger-seeded fruits weighing more than 400 g was approximately 60% of that of the total number of harvested fruits with 4 applications, followed by nearly 45% with 2 applications and approximately 25% in the control. Spraying the solution 4 times increased the ratio of seedless fruits weighing more than 200 g but did not produce any seedless fruits weighing more than 400 g. More frequent applications of the solution to panicles delayed the fruit maturity and decreased the sugar content in ripened fruits. These results indicate that the combined application of 10 ppm CPPU and 100 ppm GA3 from the early stage of fruit growth, which promoted fruit enlargement, has a potential to increase the commercial value of 'Irwin' mango fruits, but at the same time the treatment may decrease the quality of ripened fruit.