除葉處理對番木瓜兩性株花性型表現之影響

Defoliation Affects Flower Sex Expression in Hermaphroditic Papayas

番木瓜兩性株為台灣主要的栽培株型，其性型變異常會導致產生畸形果或無法結果，因而影響產量及品質。為瞭解除葉對番木瓜兩性株花性表現之影響，本試驗以台大選系耐（抗）病品系8、11號番木瓜兩性株為材料於花期進行不同程度之除葉處理。同時亦栽植‘台農2號’以比較田間各品種（系）間及處理間花性表現之差異。‘台農2號’正常花比率在試驗期間逐漸下降；台大選系8號正常花比率則穩定維持在42.9%左右；台大選系11號正常花比率較低，雌蕊完全退化型花比率較高。花序軸頂花芽正常花表現率以台大選系8號最高（29.6%）。除葉處理對台大選二品系花性型表現均有影響，兩品系雌蕊退化型花比率皆隨著除葉片數目的增加逐漸提高，正常花及雄蕊心皮化型花比率則逐漸降低。台大選系8號留32片葉處理正常花比率可達74.6%，為本試驗各處理間最高者。 Inconsistent flower sex expression in hermaphroditic papaya plants often results in poor fruit shape andyield. The effect of partial defoliation on floral sex expression in hermaphroditic papaya plants, ring spottolerantNTU Line No.8 and NTU Line No.11, were studied. A ring spot-sensitive 'Tainung No.2' was alsogrown without defoliation treatment for comparison. Percentage of elongata flowers in 'Tainung No.2decreased along blooming season. NTU Line No.8, on the other hand, showed a consistent floral. typecombination, and had a significantly higher percentage (42.9%) of elongate flowers than other line or cultivarobserved. NTU Line No.11 produced more complete pistilloid flowers and fewer elongate flowers than theother two cultivars. The percentage of elongate flowers on the terminal position was significantly higher inNTU Line No.8 (29.6%) than that of other cultivars. Partial defoliation increased complete pistilloid flowersbut decreased elongate flowers and carpelloid flowers in both NTU Lines. Partial defoliation with 32 leavesremaining in NTU Line No.8 resulted in highest percentage of elongate flowers (74.6%) among alltreatments.