番石榴(Guava)具特殊風味，為本省鮮食及加工之重要熱帶果樹。近年來由國外引進新品種，使品質不斷提升，栽種面積更有與日俱增之趨勢，其 在果樹產業之重要性亦因而提高。但本省有關番石榴營養狀及施肥需求之基本資料仍屬闕如。本試驗利用養液栽培方法，誘發番石榴個別要素缺乏症狀，拍照記錄，以供果農目視診斷之參考。結果如下：\ud (一)缺氮：植株生長不良，由下位葉開始全株黃化。\ud (二)缺磷：成熟葉片，葉脈之間組織產生紫紅色色素，植株生長減少。\ud (三)缺鉀：成熟葉片葉緣產生暗棕色壞疽斑點漸向脈間蔓延。\ud (四)缺鈣：頂梢新葉扭曲變形，並發生葉肉褐化乾枯現象，生長受到抑制。\ud (五)缺鎂：葉脈間黃化，但主脈附近組織仍維持綠色，嚴重時葉脈間出現壞疽斑點。\ud (六)缺鐵：新葉黃白化，下位葉葉色正常。\ud (七)缺硼：生長點停止生長，新葉有不規則褐色壞疽斑點，植株矮化。嚴重時芽體發生壞死。\ud 其他缺鋅、缺錳植株，在試驗期間並未出現明顯之病徵，生長量亦未受影響。葉片分析顯示錳及銅含量仍較對照組為低，缺鋅處理，鋅含量與對照組無顯著差異。Guava, with its unique taste, is an important tropic fruit widely consumed both fresh and processed by people on Taiwan. In recent years, new cultivars were continuously introduced from foreign countries, the jqualities of the fruit were hence vastly improved, which not only brought about a trend of constant expansion of cultivting areas but also elevated its importance among the fruit plants. Despite the promising prospects, our knowledge about the basic needs of the plant, are quite limited. In this study, endeavors are made to induce symptoms of essential element deficiency in guava via water culture. The results are photographed to serve as a convenient aid for farmers in case of visual diagnosis. Yhe data obtained from our investigation are as follows:\ud A.Nitrogen deficiency-Growth of the plant was adversely affected. Yellowing of the leaves began from the lower portion of the seedling and than spreaded to the entire plant.\ud B.Phophorus deficiency-Tissues between the veins of the mature leaves developed purplish red pigments. Growth of the plant was hampered.\ud C.Potassium deficiency-The edges of the leaves in the middle of the plant showed dark brown cankerous spots which graduately invading the area between the veins.\ud D.Calcium deficiency-Distortion and disfiguring of the new leaves at the top of the plant with concurrent browning and wilting of leave tissues were observed. Growth of the plant was retarded.\ud E.Magnesium deficiency-Yellowing in the areas between veins was evident. However, the tissues near the main veins were still quite green. In serious cases, necrosis were also found between veins.\ud F.Iron deficiency-New leaves turned yellowish white in otherwise normal-looking plants.\ud G.Boron deficiency-Fail to generate growth points. New leaves were found dotted with irregular brown cankerous spots. The plant was also dwarfed. Death of the buds would occure when situation worsened.\ud No perceptible symptoms of any sort were detectable in plants subjected to low zinc and manganese treatments. The growth of those plants were normal, leave element analysis indicated that Mn- and Cu- deficient plants contained less amounts of the specified metal ions than the control. On the other hand, the Zn content of the deficient plants and that of the control was about the same
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