Abstract:

Aiming at the problems in the production of Shatian pomelo, such as low flower amount and low fruit setting rate, effective methods to increase the amount of flowers and improve the fruit setting rate were summarized. This experiment was carried out in Guilin with a new variety of Shatian pomelo ‘Guiyou No.1’ as the experimental material. Six treatments and a control were set to promote flowering, including treatment 1: spraying 25% PP333 suspension 500 times twice in late September; treatment 2: spraying 25% PP333 suspension 500 times twice in early October; treatment 3: girdling in late September; treatment 4: spraying 25% paclobutrazol suspension 10 g/plant in late September; treatment 5: spraying 25% paclobutrazol suspension 500 times + girdling in late September; treatment 6: ringing in late September; CK: clean water control. Fruit retention tests were conducted by spraying the whole tree or fruits with 80% 2,4-D wettable powder 10 mg/L solution, spraying fruits with 80% 2,4-D wettable powder 12 mg/L solution, and water control during the first physiological fruit drop period. The results of different flowering promotion treatments significantly increased the number of mother branches and flowers. Among them, treatment 1 had 111.00-168.67 mother branches with 866.33-1877.00 flowers, and treatment 4 had 98.67-137.0 mother branches with 723.00-1269.00 flowers. The effects of these two treatments were significant and stable. When the weather was normal, there was no significant difference in the fruit setting rate between the flower-promoting treatments and the control, but when the rainy weather continued, there was a tendency of the fruit setting rate decrease; the larger the flowering amount, the lower the fruit setting rate was. The results of fruit retention showed that in the first physiological fruit drop period, when the whole tree or fruits were sprayed with 80% 2,4-D wettable powder 10 mg/L solution, the fruit retention rate was 16.58%-17.09% or 14.70%-16.06%, respectively; when the whole tree was sprayed with a solution of 80% 2,4-D wettable powder 12 mg/L, the fruit retention rate was 13.89%-14.36%, while the fruit retention rate of the control was only 7.10%-8.40%. From late September, spraying paclobutrazol, conducting main branch girdling, spraying paclobutrazol+ main branch girdling, and main branch ringing could significantly increase the number of mother branches and flowers. During the first physiological fruit drop period, spraying the whole tree or fruits with 80% 2,4-D wettable powder 10 mg/L solution or spraying fruits with 80% 2,4-D wettable powder 12 mg/L solution could increase the fruit retention rate of ‘Guiyou No. 1’.

Key words: Guiyou No. 1, growth regulator, girdling (ringing), flower amount, fruit setting rate