遮光、溫度與無機養分對擎天鳳梨‘Cherry’生長之影響

Abstract

擎天鳳梨之花苞片顏色鮮豔且觀賞期可長達半年，為優良之景觀擺設或室內觀賞盆栽，然而目前仍缺乏光度、溫度及養分供應相關科學性研究，因此本試驗主要目的為了解光度、溫度及肥培管理等栽培條件對擎天鳳梨‘Cherry’營養生長之影響。 巨量元素於擎天鳳梨葉片中分布有差異，K及Ca濃度呈現梯度分佈，葉基K濃度顯著向葉尖逐漸減少，Ca濃度則由葉基向葉尖逐漸增加。 當遮陰程度增加至77 %(中午平均光度214 μmol•m-2•s-1)，植株總葉面積、新生長葉片數量、地上部乾重及根部生長明顯降低。葉片綠色組織厚度隨光度提高而增厚，放射狀細胞內的葉綠體顯著較多。在20 %遮陰下生長之葉片K濃度顯著較高。 以25/20℃配合施用100 %強生氏營養液較有利於擎天鳳梨營養生長，具較高地上部、根部乾重、總葉面積及新生長葉片數。當養液濃度由50 %提高至200 %強生氏營養液，葉片長度增加。與25/20℃和20/15℃處理相比，以30/25℃處理之葉片顯著較薄且較長。較高溫度(35/30℃、30/25℃)下加速葉片水分散失，葉尖焦枯及內捲葉片數目顯著增加。 施用P濃度15-131 mg•L-1範圍內，擎天鳳梨葉片P濃度由1.2 g•kg-1提高至5.4 g•kg-1，兩者呈高度直線正相關。以10N-13.1P-16.6K處理之葉片P濃度明顯已超過適當濃度，植株葉片數、株高、根部乾重、葉綠素計讀值、葉片寬度等生長受到抑制，大量葉片黃化或焦枯。 施用15 mM完全銨態氮處理者之新生長葉片數、株高、葉面積、地上部乾重及根部乾重皆明顯較低，植株葉尖或葉緣出現大量淡黃及褐色壞疽。硝酸態氮及尿素處理之植株外觀形態不同，尿素處理之株高及幅寬皆比硝酸態氮處理小，葉片形狀短胖，長寬比明顯較小，且尿素態氮較有利於葉片及葉面積的增加。 擎天鳳梨對氮需求低且利用效率高，氮濃度由0 mM增加為施用4 mM時，葉片綠色組織厚度、葉綠素計讀值與生長量顯著增加，其植株淨光合作用能力亦較其他處理者高。然而施用16 mM N較有利於營養生長，其總葉面積、地上部乾重及根部乾重較高。施用N濃度0-32 mM範圍內，葉片N濃度由6.0 g•kg-1提高至27.5 g•kg-1，兩者呈直線正相關。地上部乾重與根部乾重為直線正相關。 施用0 mM K時，葉片寬度顯著減小。隨施用K濃度提高至6 mM，老葉(第15片葉)之K濃度顯著增加，葉片總厚度、上表皮及儲水組織厚度顯著增加，植株老葉出現黃斑及黃化葉片數亦減少。較高氮鉀比例(N16K2)處理下，葉片寬度顯著減少，黃斑及黃化葉片數則顯著增加。

Plants of Guzmania lingulata have colorful bracts, making them widely used for landscape decoration or indoor potted flowers. Information on shading, temperature and nutrient supply is presently limited. The objectives of this thesis were to determine the effects of light intensity, temperature and nutrition on growth of G. lingulata ‘Cherry’. The distribution of K and Ca concentration was gradient in the G. lingulata ‘Cherry’ leaf blade. Leaf K concentration decreased, while Ca concentration increased, from leaf base to tip. Under 77 % shading (average noon PPF 214 μmol•m-2•s-1), the total leaf area, leaf number, shoot and root dry weights decreased. Mesophyll layer thickness increased with increasing irradiance. More and smaller chloroplasts were also observed in the mesophyll stellate cells under higher irradiances. Leaves grown under 20 % shade had a higher leaf K concentration. At 25/20℃, applying 100 % Johnson’s solution resulted in the highest shoot dry weight, root dry weight, total leaf area and new grown leaves of G. lingulata ‘Cherry’. Leaf length increased with increasing Johnson’s solution concentration from 50 % to 200 %. Leaves were thinner and slighter at 30/25℃ than those at 25/20℃ or 20/15℃. Number of the incurved and necrotic leaves increased as temperature increased. Applying P concentration from 15 to 131 mg•L-1 increased leaf P concentration linearly. Application of 10N-13.1P-16.6K decreased the leaf number, plant height, root dry weight, SPAD-502 value and blade width, and exceeded in leaf P concentration.