红肉脐橙落花落果规律的观察研究

2008年对红肉脐橙生理落果进行观察研究，以揭示其落花落果规律，为制定保花保果技术措施提供依据。结果表明：红肉脐橙落蕾落花时间集中在4月上中旬，4月12日出现明显的落蕾落花高峰，4月21日开始第1次生理落果，持续35d，于5月26日结束，其中5月4日和5月9日分别出现2次落果高峰；落花后18d，即5月11日开始第2次生理落果，至6月27日结束，持续47d，其中5月17～18日和6月9日分别出现2次落果高峰；红肉脐橙落花、第1次、第2次生理落果分别占总落花落果数的80．7％、16．8％和2．5％，坐果率为0．89％。生理落果以第1次生理落果为主，建议在谢花期、第10：生理落果高峰前的4月底或5月初，各喷施1次50×10^-6 GA3溶液保果，5月中旬第2次生理落果高峰前再喷施1次；红肉脐橙脐黄率为8．8％、裂果率为15．2％，裂果率偏高乃久旱骤雨所致。

Elucidation of mechanism for flower and fruit dropping in Cara Cara navel oranges

An experiment has been conducted to elucidate the physiological mechanism of flower and fruit dropping in Cara Cara navel oranges in 2008. The results showed that flower bud and flower dropping in Cara Cara navel oranges starts in the early April and reached at the peak till 12~ April. The first physiological fruit dropping was observed from 21^sh April to 26^th May with the peak times between 4^th and 9^th May, and lasted 35 days. The second physiological fruit dropping was from 11^th May to 26^th June, and lasted 47 days with the peak times between 17-18^th May and 9^th June, respectively. The flower dropping rate at flower dropping stage and fruit dropping rate at the first and second physiological fruit dropping stage of Cara Cara navel oranges was 80.7%, 16.8% and 2.5%, respectively, and fruit setting rate was 0.89%. Fruit dropping mainly occurred at the first physiological fruit dropping stage, therefore, for its prevention, 50×10^-6 GA3 solution may be sprayed initially in late April or early of May at flowering stage or before the peak time of the first physiological fruit dropping. The second spray should be applied in mid May, before the peak of the second physiological fruit dropping. It was found that navel yellow rate of oranges was 8.8% and fruit cracking rate was 15.2% which was caused by rain after a long periods of drought.