兩性株性型表現在番木瓜品種間之差異

Hermaphroditic Sexual Expression on Papaya Cultivars

從1995年到1998年在屏東產地的網室內栽種'S19-13'、‘日陞’、‘泰國’及‘菲律賓’等番木瓜品種，一樣的環境條件下施行兩回相同的試驗以比較兩性花性型表現的差異。‘泰國’及‘菲律賓’的正常兩性花表現率約20%到50%，'S19-13'及‘日陞’平均約有70%的正常兩性花，此結果在統計上是呈極顯著差異。番木瓜剛開花階段，正常兩性花漸增加到高峰，是時雄蕊心皮化型兩性花則漸增加，隨後正常兩性花漸增達到高峰，此時雌蕊退化型兩性花則漸增加，如此規律變化可見於四番木瓜品種。此種規律在‘泰國’及‘菲律賓’兩性株性型表現變化激烈，'S19-13'及‘日陞’兩性株性型表現雖有此變動趨勢，但幅度較少。植株生理年齡抑或溫度變動皆可影響兩性株的性型表現，但品種的表現才是主要的影響因子。

Four papaya cultivars including 'S19-13' (a former breeding line of 'Tainung No. 5'), 'Sunrise', 'Thailand', and 'Philippine', were grown under similar environmental conditions in net house cultivation to determine differences on hermaphroditic sex expression. Two separate experiments at the same location were practiced in Ping-tung field from 1995 to 1997. Nearly 70% flowers were elongata produced on 'S19-13', and 'Sunrise', compared to 'Thailand', and 'Philippine' that was varying from 20% to 50% in experiments. At dehiscence, elongata flower ratio was increased graduate then decreased; carpelloid was increased at that time; more elongata flowers were increased again then following by pistilloid increasing steadily at one year cycle. Fluctuation was varied among papaya cultivars at patterns of hermaphroditic expression. Apparently, 'Thailand', and 'Philippine' had a considerable larger amount of sexual differentiation to carpelloid or pistilloid forms. Hermaphroditic flower sexual differentiation on 'S19-13', 'Sunrise' did not vary much, but the pattern was similar. Temperature and/or mature stage influenced hermaphroditic sexual expression. Cultivars with significantly higher rate of elongata would have less fluctuation no matter at different environment or at plant stages of physiology.