愛文檬果花期與無子果生成之關係研究

The Relation between Flowering Period and Seedless Fruit Formation of Irwin Mango (Mangifera indica L.)

愛文檬果（Mangifera indica L.）所發生的無子果體積與重量均較正常果為小，但其果肉與種殼的比小為正常果的3.14倍。在玉井檬果專業區同一果園不同坡向會影響無子果的產生，在北坡向無子果的發生率為南坡向的7.23倍，依開花期間兩坡向之溫度比較，北坡向溫度較低可能是造成此一差異的主要原因。在開花始、中期（12月～3月）氣溫偏低（18.7℃以下）且多雨，完全花與雄花之機能雄蕊花紛生成率很低，此一期間著果的花序無子果發生率高；而開花終期（4月）溫度升高（高於20℃），花粉生成率高，石果枝條之無子果發生率變低。完全花經人工除雄控制授粉，包括除雄套袋不授粉、同品種及不同品種間之混合授粉，採得成熟果實皆為無子果，人工授粉並不能確保正常果的產生，足見溫度在無子檬果之形成上較授粉更具影響作用。

The volumn and weight of seedless Irwin mango were less than those of normal fruits, but the pulp/atone ratio of the former wan 3.14 times of the latter. Study at one orchard at Yu-Ching of Tainan indicated that different slope direction influenced the formation of seedless fruits. The number of seedless fruit formed on northern slope direction were 7.23 times more than that of the southern one. From the study of temperature record, the formation of more seedless fruits on the northern slopeland seemed to be correlated to the generally lower temperature than the southern slope during period. In early and middle part of the flowering period (from December to March), the lower temperature (＜18.7℃) and more rainy days resulted in very low percentage of functional stamen in both perfect and staminate flowers, which panicles set fruits with very high proportion of seedless fruits. In the late part of flowering period (April), when temperature rose (＞20℃), functional pollen formed, with very few seedless fruits produced Perfect flowers were emasculated and, followed either by no pollination or pollination with bulk pollen collected from same variety or from different varieties. Whether pollinated or not, all fruits harvested were seedless. This indicates that artificial pollination does not quaran-tee the formation of normal fruits. The temperature effect seems to be more responsible than pollination for the formation of seedless mango fruit.