Gibberellins對柑橘生長與養份吸收的影響

Growth Responses and Nutrient Absorption by Citrus as Influenced by Gibberellins

一、柑橘幼苗經Gibberellic acid 100ppm., 50µg/pt. 一次之處理，或栽培於Gibberellic acid 0.5 ppm 之培養液中，植株均有被刺激生長之現象，而此效力隨所用G. A.濃度之增加而增加。其時效之長短，視濃度及用量多少而不一。二、徒長之幼苗芽端易受日光灼傷而枯凋。但幼芽枯凋後，反促進側芽之叢生與徒長。三、經Gibberellic acid處理後之柑橘植株，其植株隨然徒長甚長，但其乾溼重量，並無顯著之增加。四、將100ppm. 之Gibberellic acid塗布於植株基部之一老葉片上，其對植株之刺激生長作用，與Gibberellic acid用於頂芽及根部有同樣之效果。五、以Gibberellic acid處理後植株，其徒長之葉片顏色變淡黃綠色，葉片變窄長，葉柄延長。六、柑橘葉部可以吸收並利用Urea及Gibberellic acid以1:700之混合液，雖然Gibberellic acid對於植株之生長刺激不明顯，但Urea對於補救因，Gibberellic acid所發生之黃斑病(Chlorosis)確有功效。七、經Gibberellic acid處理後之柑橘葉部，含氮量減少，但可以適量之硫酸銨作肥料補救之，磷素之含量，處理與未處理者無顯著之差異，但鉀素之含量，由於KCl作肥料而使G. A.處理之植株中，含鉀量增加。八、由放射性同位鈣素之應用，顯示Gibberellic acid處理之植株，要比未經處理者對Ca45之吸收量減低。九、當Gibberellic acid加入培養液中，常易誘發兩種Fungus因而使植株根部發育受阻，且使其腐爛，此兩種Fungus經培養鑑定為Pythium及Fusarium, 均為土壤中，常見之真菌，由於經Gibberellic acid處理之植株根部發育受阻，以致影響其對氮素及其他營養元素之吸收，因而使葉部之含氮量及其他元素之含量減少，而使葉色變淺黃綠色。

Since the potentialities of auxin were first recognized some twenty or thirty years ago, no other plant hormones have drown so much attention as the gibberellins to the botanists and horticulturists. Gibberellins are produced by a fungus named Gibberella fujikuroi (Saw.) Wr. These compounds strikingly stimulate the growth of many plants, promote flowering in some cases, and cause various other interesting responses morphologically and physiologically. Different responses of gibberellins were shown in most kinds of plants studied, the most obvious response was stem elongation, and different genera gave different responses. Wittwer and Bukovac have evaluated in detail the implications of this development for agriculture and horticulture, they came to a conclusion that a given species or variety responds to a wide range of various concentrations, and different species and varieties within a species react differently to the same treatment.