염생식물 나문재의 염농도에 따른 생장 및 생리적 특성

Growth and Physiological Characteristics in a Halophyte Suaeda glauca under Different NaCl Concentrations

Abstract

본 연구는 염 농도 별 나문재의 생장과 식물체 내의 무기 이온과 아미노산 함량, 광합성 효율 등을 조사하여 염농도에 따른 나문재의 생리적 특성을 구명하고자 실시하였다. 나문재의 초장, 분지수, 건물중을 조사하였을 때, 50 mM에서 최적의 생육 상태를 보였고 50~100 mM의 염농도 범위에서 생육이 양호하였다. 식물체 내 무기이온의 함량은 염농도가 높을수록 Na 이온의 함량은 증가하였고, K, Ca, Mg 이온의 함량은 감소하였다. 식물체 부위별 무기이온의 함량은 Na 이온의 함량은 지하부보다 지상부에서 더 높게 나타났다. 염농도에 따른 식물체의 유리아미노산 함량을 보면, proline을 제외한 glycine 등의 16종의 아미노산은 공통적으로 생육에 최적 염농도인 50 mM에서 함량이 가장 낮게 나타났으며, proline은 정반대로 50 mM에서 현저히 높은 함량을 보였다. 염농도에 따른 광합성 효율은 50 mM에서 가장 높았으나 400 mM의 높은 염농도에서도 광합성효율의 저하는 크지 않았다. 결론적으로, 나문재의 생육에 최적 염농도는 50 mM이었지만, 염농도 변화에 따른 식물체 내의 무기이온, proline 등의 아미노산 함량의 변화, 그리고 고염조건에서도 광합성 효율을 유지할 수 있는 생리적 특성으로 0~400 mM의 넓은 범위의 염농도에서도 생육이 가능하여, 염농도의 변이가 큰 신간척지에 적합한 염생식물로 판단된다.

This research was carried out to investigate the plant growth, inorganic ion and amino acid content characteristics in a halophyte, Suaeda glauca, under different NaCl concentrations for cultivating in the reclaimed land. S. glauca was hydroponically cultivated under 0, 50, 100, 200, 300 and 400 mM NaCl concentrations with Hogland's nutrient solution. To evaluate growth response under different NaCl concentrations, plant height and number of branches, dry weight, Fv/Fm value, and photosynthetic efficiency were investigated. To find out physiological characteristic, inorganic ion contents and amino acids in the plant were evaluated. The optimum concentration of NaCl for plant growth were 50 mM. The plant growth were gradually decreased in the concentration ranged from 100 to 400 mM. As increasing of NaCl concentration, Na ion was increased, but K, Ca, Mg ions were decreased in the plant. The amino acid contents were varied due to NaCl concentrations, but most of amino acids content in total plant was the lowest at 50 mM. Conversely, proline was exceptionally high at 50 mM of NaCl concentration. The Fv/Fm value was the highest at 50 mM of NaCl concentration. From these results, the optimum salt concentration for the growth of S. glauca was 50 mM, but the plant seems to adapt in a variety of salt environments in view of the change of ions and amino acids depending on salt concentration and the maintenance of photosynthetic efficiency even under high salt condition.

Fig. 1. Number of branches (A), Plant height (B), and Dry weight (C) of Suaeda glauca under different NaCl concentrations (mM). Within the same column, means followed by the same small letter are not significantly different, as determined by DMRT at α = 0.05. Vertical bars indicate standard deviations.

Fig. 2. Ion content of Suaeda glauca under different NaCl concentrations.

Fig. 3. Proline contents in root, stem and leaves of Suaeda glauca depending on NaCl concentrations (mM). Within each plant part, vertical bars with same letters are not significantly different by DMRT at α = 0.05. Vertical bars indicate standard deviations.

Table 1. Ingredients of Hogland’s solution.

Table 2. Ion contents in leaves, stem, and root of Suaeda glauca depending on NaCl concentration. Within the same column in each plant part, means followed by the same small letter are not significantly different by DMRT at α = 0.05.

Table 3. Amino acid content (μg/g) of Suaeda glauca under different NaCl concentrations. Within the same raw, means followed by the same letter are not significantly different, as determined by DMRT at α = 0.05.

Table 4. Photosynthesis efficency (Fv/Fm value) of Suaeda glauca under different NaCl conditions.