Effects Of Chemical Regulation On Flowering And Fruit Drop, Cracking And Quality In Litchi

Lychee(Litchi chinensis Sonn.) is an evergreen subtropical fruit trees of southern origin of China. In litchi production, some cultivars like ‘Feizixiao' are difficult for fruit setting due to the defects of flowering habits such as a short period for female flowering, some cultivars like ‘Nuomici' and ‘Wuheli' have very low yield due to serious preharvest fruit abscission and cracking. In this study, the effects of uniconazole and ethephon spraying on flowering, fruit set and fruit quality of ‘Qinzhouhongli' and‘Feizixiao' litchi were evaluated. In addition, we also use ‘Baitangying', ‘Nuomici' and‘Jizuili' as materials to evaluate chemical control and its impact on litchi fruit drop,cracking and fruit quality. The results are as follows:1. Uniconazole plus ethephon treatments could prolong the first female flowers and the second male flowers open time of ‘Qinzhouhongli' and ‘Feizixiao' to a certain extent.40 ppm and 50 ppm uniconazole + ethephon treatments are better than the control, these two treatments extended the first female flowers open time by 15.6% and 13.7% compared to the control respectively, and they also extended the second male flowers open time by15.1% and 23.3%. This phenomenon is conducive to pollination and fertilization effect of these two varieties of litchi, and it can improve fruit set and yields of these two varieties.2. Three concentrations of uniconazole + ethephon treatments were able to effectively reduce fruit drop of ‘Qinzhouhongli' litchi. Among them, 50 ppm uniconazole + ethephon is the best treatment. The cumulative rate of this treatment was reduced by 20.3%, the other two treatments were also lower by 18.4% and 15.5% compared with the control. Once spray of uniconazole + ethephon can improve the fruit quality of ‘Qinzhouhongli' to certain extent. But for ‘Feizixiao', it have little effect on fruit inherent quality.3. Chemical Regulation treatment by spraying ‘Baoguofangliesu' can effectively reduce the preharvest fruit drop and cracking rate of ‘Nuomici' and ‘Baitangying' to someextent. In the meanwhile, spraying ‘Baoguofangliesu' also significantly improved the fruit quality for 'Baitangying' litchi, but had little influence on ‘Nuomici' litchi fruit inherent quality. But the treatment increased the average fruit weight for ‘Nuomici” litchi by 9.6%.Moreover, ‘Baoguofangliesu' spraying did not affect the fruit drop, cracking and fruit quality for 'Jizuili' litchi.