Water Relations Parameters of Rhododendron micranthum Turcz. from P-V Curves

Determining plant moisture characteristics is an essential study not only for cultivation, but also for ex-situ conservation. In this study, employing pressure-volume curve we examined moisture characteristics of Rhododendron micranthum, known as rare plant, with the aim of its ex-situ conservation. Several individuals growing in Mt. Worak, Youngwol-gun Yeonha-ri and Bongwa-gun Seokpo-ri were selected for this study, from which we collected leaves. The original bulk osmotic pressure at maximum turgor(${{\Psi}_o}^{sat}$)was -1.5 MPa in those of Mt. Worak and Seokpo-ri, which is somewhat lower than that of Yeonha-ri(-1.2 MPa). It appeared that the osmotic pressure at incipient plasmolysis(${{\Psi}_o}^{tlp}$) of leaves collected in both Mt. Worak and Seokpo-ri were -1.29 MPa, and -1.26 MPa, respectively, which are lower than that of Yeonha-ri(-1.02MPa). Maximum bulk modulus of elasticity($E_{max}$) was 14.0 MPa, 8.67 MPa in leaves collected from both Seokpo-ri and Mt. Worak, respectively, those value of which were approximately 3 times higher than that of Yeonha-ri(4.00 MPa). The values of $RWC_{tlp}$(Relative water content at incipient plasmolysis) of leaves collected in three areas, were roughly 83%, suggesting that Rhododendron micranthum has relatively high capability of containing water. Our finding on moisture characteristics of Rhododendron micranthum is similar to those of other Rhododendron spp. We suggest that individuals growing in both Worak and Seokpo-ri, are preferable to those in Yeonha-ri for ex-situ transplantation since those individuals are found to have better drought resistance.

P-V곡선에 의한 꼬리진달래(Rhododendron micranthum Turcz.)의 수분특성

식물 수분 특성을 규명하는 것은 재배뿐만 아니라 현지외 보전에도 필수적인 연구이다. 본 연구에서는 희귀식물로 알려진 꼬리진달래의 현지외 보전을 목적으로 P-V 곡선법을 이용하여 수분특성을 조사하였다. 꼬리진달래 잎의 최대팽압시의 삼투포텐셜은 월악산과 석포리의 개체가 각각 -1.5 MPa 이었고, 연하리의 삼투포텐셜이 -1.2 MPa로 다소 높게 나타났으며, 초기원형질분리점의 삼투포텐셜은 월악산 -1.29 MPa, 연하리 -1.02 MPa, 석포리 -1.26 MPa로 연하리의 초기원형질분리점이 다소 높게 나타났다. 꼬리진달래의 세포막의 최대탄성계수($E_{max}$)값은 석포리 14.0 MPa로 나타냈고, 월악산 8.67 MPa로 다소 낮은 값을 나타냈으며, 연하리 4.00 MPa로 석포리에 비해 3배정도 낮은 값으로 나타났다. 초기원형질분리점의 상대함수율은 월악산 83.2%, 연하리 83.1%, 석포리 83.8%으로 비교적 수분보존 기능이 비교적 좋은 수종이다. 따라서, 꼬리진달래는 수분특성상 다른 진달래와 철쭉, 관목류들과 비슷한 경향을 나타냈으며 현지외 이식시 자생지간 내건성이 상대적으로 좋은 월악산, 석포리의 개체가 좋을 것으로 판단된다.