龍眼樹之開花結果習性

On the Flowering and Fruiting Habits of Longan (Euphoria longana, Lam.) Tree

觀察龍眼樹之開花結果習性，以供育種調節結果及栽培改進之參考，於1963-64在臺中近郊以福眼、十葉、南洋、青殼、晚生及扭子眼等品種觀察，結果摘要於次：（1）龍眼平均每穗結數約800-1500其中雌花佔4.4%至27.7%不等，花穗70%-82%為向外著生，內生者佔12%~19%腋生者僅5%•結果率以內生者為高。（2）花期年稍有差，開花日數約19-26天，盛花期多在花後第10天至17天，雄花較雌花雎放稍早，每日開花以午後為盛，雄花開放約41小時，雌花約72小時，開花以溫度為23°-24°C相對濕度70%-80%時為盛。（3）落花落果及結果率因品種而異，結果率高者達37%，低者不足11%，落果有三期，以第一期及第三期為盛。（4）果實大小與重量之發育，均自花後第七週起始迅速增加，果實各部分之發育，以果殼居先種子次之，果肉至後期始迅速成長，含糖量至果實接近成熟階段始劇速增加。

The flowering and fruiting habits of Longan tree have been investigated by the author during 1963 and 1964 in the vicinity orchards of Taichung City, Taiwan, China, for·the purpose of serving breeding, fruit set regulation, and culture improvement of Longan in Taiwan. The cultivated varieties used are Fu-yen (Lucky eye), Shi-yeh (Ten leaves), Nan-yong (South ocean), Chin-ker(Green peel), Wan-sen (Late), and Nu-tsz-yen (Button eye). The results obtained are as follows: 1. The flowercluster of Longan tree has an average of about 800-1500 flowers, only 4.42-27.73 among them are female. 2. About 70% of flowers are found located on the middle and lower branches of the flower cluster, and the male-female flower ratio are similar for branches at all locations. 3. On the same tree, 70-82% of the flower clusters are born outwardly, 12-19% inwardly, only 5% or a little more are axillarily born. The percentage of fruit obtained is the highest for inwardly born ones. 4. The blooming date varies with year, generally it lays between late March and middle April, 19-26 days in all. 5. Male flowers usually bloom earlier than female flowers, that is about 3-5 days. 6. Longan tree blooms most abundantly in the afternoon. 70-83% of the flowers are blooming between 3p.m.-llp.m. 7. The blooming peak period varies with varieties, it is observed 12-16 days after first bloom for Shi-yeh, 10-17 days for Fu-yen. 8. On the same tree, the southward clusters bloom first. The flowers on each cluster are blooming successively upwards from the bottom. 9. The flower life found are 41 hours for male flowers, 72 hours for female flowers. 10. Longen tree blooms most luxuriantly at 23 °-24 °C, and Relative Humidity 70-80%. 11. The flower drop, fruit set, fruit drop and fruit obtained percentages vary with varieties. It is found that about 37% of female flowers can grow into fruits for Wan-sen, and less than 1196 for Nan-yong. 12. Three fruit drop stages are found for Longan tree. The first stage is one week after blooming, with fruits dropped amounts to about 50% of those\for the three stages, the second stage is 3-5 weeks after blooming, with little fruits dropped, and the third stage is 9··10 weeks, the dropped fruits blooms most luxuriantly at 23 ° -24° C, and Relative increase, but the amounts vary with varieties. 13. Both the increment of fruit size and weight begin increasing rapidly at the seventh weeks after blooming, a lag is found existed at the tenth and eleventh weeks, and then grown rapidly till harvest. 14. As for the growth and development of Longan fruit, the peel grows first, then the seed, and the endocarp begins to grow at the later stage of development rather rapidly till ripe. 15. The sugar content of Longan fruit begins to increase quickly at the later stage of development till full ripe.