鈣與鍶對爵床植株生長及鐘乳體結晶形成的影響

Abstract

本篇論文以爵床（Justicia procumbens）為材料，水耕栽培方式供應不同濃度鈣及鍶離子，並配合光學與電子顯微鏡技術，探討鈣缺乏與鍶毒害對幼苗與植株生長及子葉與真葉之形態、葉長及各類細胞分佈的影響，另觀察石胞及其內晶體外形變化，計量並分析各組單位面積內晶體的密度與晶體總面積及單一晶體面積之差異。 不同濃度鈣離子實驗結果顯示，植株高度會隨鈣離子濃度供應量增加而提高，葉片長度亦隨鈣離子供應量增加而增長。子葉與真葉對缺鈣（＜0.19mM）的反應相似，皆表現出葉片下垂反捲、新葉顏色較淡綠的現象，嚴重者則頂芽停止生長或壞死，雖然缺鈣不至於影響葉表皮組織各種細胞的產生，但葉肉細胞會排列較緻密，且葉綠體外形變得較圓胖、內囊膜構造較少，石胞細胞壁質地顯得較疏鬆。在許多缺鈣組葉片切片中常可在細胞周圍觀察到含電子緻密性物質之小胞。缺鈣雖不影嚮晶體的外形、密度及單位元葉面積內的晶體總面積，但單個晶體的面積會變小。隨培養液中鈣離子供應量的減少，鐘乳體結晶中的鈣含量亦相對減少，且在較缺鈣條件下，植株葉片及子葉內常觀察到碎結晶。 綜合不同濃度鍶離子對真葉的影嚮，在有1/4Ca（0.19mM=7.6ppm）之基本鈣離子供應條件下，鍶離子濃度（＞0.75mM）過高會造成葉緣明顯有黃色斑點出現，而過多的鍶離子雖然不影響表皮組織各種細胞的產生，亦不影響晶體產生的數目，但是會使單個晶體面積及單位葉面積內晶體總面積變小，過量的鍶離子濃度亦使結晶外形產生變化，向葉基產生突起構造；此外石胞及其鄰近區域的細胞變形。經EDX測定，在定性方面，各組皆具有鈣及鎂的波峰。在鈣的含量比較上，晶體內鈣含量隨鈣離子供應量增加而提高。經拉曼光譜測定之結果，得知爵床鐘乳體碳酸鈣結晶乃為方解石。 經先鈣後鍶培養之真葉結晶，經WDX測定，鍶離子在晶體中央部位及邊緣部位皆有分佈，且邊緣部位會比中央部位高，由晶體之外形為長條眉形且其內部為層狀構造，推測晶體堆積的方式是由晶體外部堆積上去，及其生長的方向應是向長軸兩端生長。

Effects of different levels of calcium and strontium supply on the seedlings and plants growth of Justicia procumbens and on the formation of lithocysts and cystoliths, were morphologically and X-ray microanalytically studied. The results showed that the height of seedlings and plants and the length of leaves were declined with decreasing the concentrations of calcium in culture solutions. The symptons of calcium deficiency (< 0.19mM) on seedlings and plants were similar: smaller, pale green and twisted leaves; necrosis or death of shoot apex; narrow intercellular space within mesophyll. There were also fewer thylakoid membranes in chloroplast and looseness of cell wall of lithocyst. Besides, there were electron-densed cytoplasmic strands and vesicles between cystolith and cell wall in lithocyst. Calcium deficiency decreased the size of single cystolith and the total area of cystoliths per mm2 leaf area. The amount of calcium in cystolith also decreased from high calcium to low calcium supply. The symptons of excess strontium (>0.75mM) on leaves were yellowrish spots on leaf margin, and necrosis of lithocysts and neighboring cells, cystoliths with branches. Excess strontium decreased the size of single lithocyst and total area of cystolithes per mm2 leaf area, but the density of cystolithes was not obviously affected. The results of X-ray microanalysis on the cystoliths from all the tested groups showing that calcium and magnesium were detected in the cystolith, and their amounts were higher at core than at edge. Strontium was only detected on the groups with strontium in the culture solutions. The amount of strontium was a little higher at core than at edge. Nevertheless, in the transplanting experiments, plants were trasnsplanted from the 1Ca to the 1Sr solutions. The amount of strontium was higher at the edge of cystolith. The crystal habit of lithocyst was calcite revealed by Raman spectroscopy.