木賊葉木麻黃苗木對水分逆境之反應

Response of Water Stress on Casuarina equisetifolia Seedlings

木賊葉木麻黃迄今仍為海岸防風林的重要先驅造林樹種，近年來在強烈的逆境下，呈現易衰退枯萎之象，然以木麻黃為海岸林之第一線樹種仍具不可替代之地位，而海岸沙丘乾旱環境為林木生長發育的主要障礙因子之一，故本研究以水分生理為主題，探討適合木賊葉木麻黃苗木生長之水分環境。試驗結果顯示，木麻黃苗木對乾旱極具忍耐力，能維持平緩的生長量，且各處理鮮重之含水率相近（在70%左右），而乾物量累積以100%處理者為最多達23.12g，隨著土壤含水率之減少，苗木乾物量累積亦愈少。且受缺水情況之加重，光合作用速率亦隨之下降，但可溶性蛋白則呈逐漸累積，最多為30%處理者達5.6mg g^(-1)，提升其滲透潛勢，以利植物體水分之維持。斷水期間，葉片水勢逐漸下降，缺水處理的苗木藉由關閉氣孔來減少水分喪失，分別在第17、21天達到黎明前最低水勢，並能提高葉黃素循環增加對過多能量的消散，其葉片反射光譜PRI最低降至-0.062，且隨著缺水強度增加對木麻黃苗木之健化效果愈明顯。 Casuarina equisetifolia is the important windbreak species used to planting at the sharp end, it has shown declined because of the foul environment and typhoon stricken continuously. C. equisetifolia had grow hardly. In order to understanding the natural regeneration mechanism of C. equisetifolia, we set various water treatment and observed the responses on phenology and physiology. r C. equisetifolia shown the great tolerant during water stress. C. eqrtisetifolia can keep mild growth and maintained the same water content (around 70%) with control in the drought treatment. C. equisetifolia accumulated soluble proteins during drought situation. C. equisetifolia had 5.6 mg g^(-1) of soluble proteins in. water content 30% treatment, that will probably increase the osmoregulation to absorb water. Seedling in droughty treatment reduced water loss by closing stomata, and enhanced the ability of xanthophyllcycle (minimum PRI≒-0.062), and shown hardened effect by enhanced water stress.

Casuarina equisetifolia is the important windbreak species used to planting at the sharp end, it has shown declined because of the foul environment and typhoon stricken continuously. C. equisetifolia had grow hardly. In order to understanding the natural regeneration mechanism of C. equisetifolia, we set various water treatment and observed the responses on phenology and physiology. r C. equisetifolia shown the great tolerant during water stress. C. eqrtisetifolia can keep mild growth and maintained the same water content (around 70%) with control in the drought treatment. C. equisetifolia accumulated soluble proteins during drought situation. C. equisetifolia had 5.6 mg g^(-1) of soluble proteins in. water content 30% treatment, that will probably increase the osmoregulation to absorb water. Seedling in droughty treatment reduced water loss by closing stomata, and enhanced the ability of xanthophyllcycle (minimum PRI≒-0.062), and shown hardened effect by enhanced water stress.