蕹菜種子生產改進技術之研究(I.)開花習性與栽培方式對不同品種蕹菜種子生產力之影響

Abstract

蕹菜是一種耐熱與耐濕性很強之半水生蔬菜，在位於亞熱帶地區之本省，屏東尖葉青骨蕹菜或白骨大葉蕹菜每年均從9月至翌年之4月陸續開花，花序是腋生之聚繖花序，每一花序由3-7朵花組成，是一種兩性整齊之合瓣花，形狀與甘藷花相似，蕹菜開花之順序為由下面節位之花穗漸次往上開，在同一花穗上亦由下面之花朵順次往上開花，開花受精後約1.5-2個月蒴果與種子成熟，每一蒴果含有種子2-6粒，但以4粒居多。 兩品種蕹菜除開花時間外，各園藝性狀均無顯著之差異，白骨蕹菜比青骨蕹菜較早開花，栽培環境（水田或旱田）對蕹菜之開花時間、分蘗能力、落花率、結實率、蒴果種子數、種子百粒重及種子＼藁比均無顯著影響，旱田栽培之情況下，白骨與青骨兩品種蕹菜均能產生較多之花數與蒴果，藁重與種子產量也有顯著之差異存在。 旱田栽培之種子產量為每公頃1,172 kg，幾乎為水田產量562 kg之二倍，青骨蕹菜旱田栽培之種子產量也比白骨蕹菜高，水田栽培者，兩品種蕹菜之種子產量雖無顯著差異，但白骨蕹菜之種子產量似乎較高，由此獲知白骨蕹菜較適合水田採種栽培，而青骨蕹菜更適合於旱田採種哉培，此種資料可提供農民蕹菜採種之應用與學術研究之參考。 Water convolvulus (I pomoea aquatica Forsk.) is a semi-aquatic vegetable tolerant toward heat and flooding. Two popular cultivars, cv. Pingtung Green Stem (pointed leaf) and cv. White Stem (broad leaf) flower continuously from September through April in the subtropical area of Taiwan. The inflorescence is axillary cyme consisting of 3-7 sympetalous flower same as that of sweet potato. The flowering sequence is generally from the lower node continuously to upper node. Flowers of the same inflorescence also start flowering in the lower part and proceed to the upper part. The capsule and seed mature within 1-2 months after fertilization. Each capsule contains 2 to 6 seeds with an average of 4. Among all the characters studied, no significant difference was found between the two cultivars except flowering time. Cultivar White Stem flowered earlier than cultivar Green Stem. The planting condition (lowland or upland) had no significant influence on the time of flowering, tillering potential, flower-drop percentage, fruit-set percentage, No. of seed per capsule, 100 seed weight and grain straw ratio. Both of these two cultivars are able to produce more flowers and capsules under upland condition. A significant higher straw weight and seed yield were also observed under upland condition. The seed yield under upland condition is 1,172 kg/ha which is about twice the amount of seed yield under lowland cultural condition (562 kg/ha). Cultivar Green Stem can produce more seed than cultivar White Stem under upland cultural condition. There is no significant difference on seed yield between these two cultivars under lowland cultural condition. Cultivar White Stem seems to be a better cultivar for seed production under lowland cultural condition and Green Stem is more favorable for upland cultural condition. This information may be valuable to farmers who are interested in water convolvulus seed production.