不同氮素型態對菊花生長開花之影響

Effect of Various N-form on Growth and Flowering of Chrysanthemum morifolium Ramat.

扦插發根之菊花（Chrysanthemum morifolium, Ramat）冬王與東亞品種，施以硝酸態氮，銨態氮、尿素態氮肥行水耕或砂耕；於春、秋季間分別進行試驗，測量植株生長勢，開花，介質之pH變化與K之吸收；並取葉片分析其無機養分。菊花之根部及大小部生長均以NO3-N最佳，U-N次之，NH4-N最差。NH4-N處理之花鮮重及大小也不及NO8-N與U-N處理者；且根部木栓狀，冬王品種在葉部有壞疽現象，而東亞品種葉對銨害反應較冬王為輕，水耕者有節間變知，葉變小且向上捲曲變形等銨毒害症狀發生。施NO8-N者，介質pH會上昇到6,24，NH4-N處理者會下降到3.38，而U-N處理之變化則居二者之間；在介質中加入CaCo8或調pH後，NH4-N處理之植株，生長勢可獲改善，但仍不及其他二處理者。東亞品種水耕試驗中，菊葉片中之K，Ca與Mg含量，以NO3-N者為基準，NH4-N處理，未調pH者，相對地各減少51，67，及52%；調pH後，三陽維子含量均顯著增加，但U-N處理之表現不明顯；該品種之砂耕試驗亦得相同結果。未調pH時，NH4-N處理之K離子吸收率遠低於NO3-N處理者，U-N處理居二者之間，調pH後，由於根之生長勢改善，NH4-N處理之K吸收率大增。本研究顯示，NH4-N與U-N處理生長勢與開花均不及NO3-N者，而施用CaCO3或調整pH可提高其肥效。

Rooted cuttings of chrysanthemum (Chrysanthemum morifolium Ramat.) cv. Tung Ya(東亞), Tung Wang(冬玉) were grown with NO3-N, Urea-N(U-N), NH4-N or NH4-N+CaCO3 under sand or water culture The experiments were conducted in the spring and in the autumum through winter season. During the growing period, quantitative measurements of growth vigor, flowering, pH of medium and K(superscript +) uptake were taken. Leaves were analyzed for mineral composition. Fresh and dry weight of shoot, root and flowers; number of leaves; flower size and number of floret in chrysanthemum were superior under NO3-N. Roots and leaver in chrysanthemum cv. Tung Wang under sand culture had shown ”NH4 toxicity” symptoms, such as darken corky and stubby roots; necrosis and chlorosis in leaves. For cv. Tung Ya under water culture, there was no visual symptom of such ”NH4 toxictity” on leaves, However, leaves were smaller and curled upward and internodes were shortened. Addition of CaCO3 or pH to the medium with NH4-N nutrition markedly alleviated the toxicity symptoms, increased cation contents in the leaves and improved growth of plants. However, growth didn't equal that on exclusively NO3-N or U-N. Since NH4 and urea nutrition significantly reduced root growth and decreased the pH in the medium, the potassium uptake at the end of the experiment by intact plant with NO3-N, Urea, and NH4-N were 190.0, 68.3, 18.3 ųM/day/plant respectively. The K uptake was improved by pH adjustment under NH4 nutrition. The results had been shown that NH4-N nutrition decreased cations content in the chrysanthemum. In comparison with NO3-N, chrysanthemum grown on NH4-N relatively decreased K, Ca and Mg content were 51, 67, 52% respectively.