插穗節位對空心菜生長影響之研究

Growth Responses of Water Spinach (Ipomoea aquatica Forsk) to DifferentAge of Cuttings from Different Portion of Shoots.

由母穗取不同節位扦插繁殖空心菜，高節位（11-12節）插穗繁殖植株形態較趨成熟，其節間較長，容易跑藤，平均開花節位低（第6節），開花數多（7.7朵）：低節位（1-2節）插穗繁殖植株，形態較為幼年，萌生枝梢數較多，節間較短，平均開花節位較高（8.6節），花數較少（4.2朵），插穗節位高低顯現幼年性（juvenility）的位置優勢（topophysis），貼地面採收後，插穗節位顯現之位置效應消失，且萌生的枝梢有回復幼年性之現象。空心菜開花及跑藤，受插穗節位高低與株齡影響。空心菜實生苗在11-14節才能開花，由株齡將近一年的老株取穗扦插，平均在6-8節有花產生，少數於第一節位即能開花。不論在冬天短日或夏天長日下，跑藤現象都會隨著株齡增長而發生，與植株成熟有關，在此試驗中，跑藤現象與開花數為極顯著正相關（0.656***），而與始花節位呈顯著負相關（-0.391***）。

Water spinach was propagated from different portions of shoots by cutting. Plants grew from higher portion of shoot had mature morphology. They have longer internodes, lower initiate-flowering node, more flower and their vine sprawled much easier. On the contrary, juvenile cuttings form lower portions of shoots had shorter internodes, higher initiate-flowering node, less flowers and more sprouts. Cuttings from different portions of shoots showed juvenile which was depends on topophysis. Sprouts re-grew from harvested cuttings near ground level did not show topophysis and appeared to be re-juvenilized. Besides topophysis, water spinach was getting mature with age. Seedlings flowered at the 11- 14th node above ground. Few cuttings even flowered at the first node. Under whether short-daylength winter or long-daylength summer, water spinach vines sprawled much easier as inceased in aging. The correlation coefficient between sprawling vine and flower number was positive significant (0.656***), but the correlation coefficient between sprawling vine and initiate-flowering node was negative significant(-0.391***) in this study. Therefore, the character of sprawling vine was related to the maturity of plant.