팔당호와 북한강, 남한강 및 경안천의 3개 지류에서 식물플랑크톤에 의한 일차생산력과 광합성 parameter의 계절적 변화를 조사하기 위하여 92년 4월, 8월과 10 월 그리고 93년 5월에 걸쳐 4회의 조사를 행하였다. 정점과 계절에 따른 secchi-depth는 0.8 (92년 10월, 경안천 정점 3)에서 2.0 m (92년 4월, 팔당댐 정점 4)까지, chl. a값은 1.7 (93년 5월, 남한강 정점 2)에서 32.8 mg m-3 (92년 8월, 팔당댐 정점 4)까지 변화하였다. 단위체 적당 일차생산력은 92년 8월(605~672 mgC m-3 hr-1)에 가장 높았으며, 정점 사이에서는 경안천 정점 3 (75~ 111 mgC m-3 hr-1)에서 가장 높은 값을 보였고, 이외의 정점에서는 16~68 mgC m-3 hr-1의 값을 보였다. 단위면 적당 일일 일차생산력은 역시 92년 8월에 가장 높았으며(8,195~9,341 mgC m-2 day-1), 92년 4월과 10월 그리 고 93년 5월에는 유사한 값을 보였다. 단위면적당 일일 일차생산력은 광도, 유광층의 깊이와 온도에 의해 영향 을 받는 것으로 밝혀졌다. Pmax와 α값은 8월에 가장 높았고, 정점간의 비교에서는 북한강 정점 1에서 가장 높았으며, 팔당댐 정점 4에서 가장 낮았다. 8월(하계)의 식물플랑크톤 군집은 4, 5월(춘계)과 10월(추계)에 비해 강한 빛에 적응되었다. Pmax와 α값은 밀접한 상관관계를 보였으나, Pmax와 Ik 그리고 Ik와 α 사이에는 상관관계를 발견하지 못하였다.

Background: This study aimed to investigate out the influence of drought stress on the physiological responses of Dendropanax morbifera seedlings. Methods and Results: Drought stress was induced by discontinuing water supply for 30 days. Under drought stress, photosynthetic activity was significantly reduced with decreasing soil water content (SWC), as revealed by the parameters such as Fv/Fm, maximum photosynthetic rate (PN max), stomatal conductance (gs), stomatal transpiration rate (E), and intercellular CO2 concentration (Ci). However, water use efficiency (WUE) was increased by 2.5 times because of the decrease in gs to reduce transpiration. Particularly, E and gs were remarkably decreased when water was withheld for 21 days at 6.2% of SWC. Dendropanax morbifera leaves showed osmotic adjustment of −0.30MPa at full turgor and −0.13 MPa at zero turgor. In contrast, the maximum bulk modulus of elasticity (Emax) did not change significantly. Thus, Dendropanax morbifera seedlings could tolerate drought stress via osmotic adjustment. Conclusions: Drought avoidance mechanisms of D. morbifera involve reduction in water loss from plants, through the control of stomatal transpiration, and reduction in cellular osmotic potential. Notably photosynthetic activity was remarkably reduced, to approximately 6% of the SWC.

Changing climate, especially water content(WC) and CO2 (CD) concentration could be effect on the growth of soybean and seed yield. So we evaluated the effects of WC and CD on the physiological characteristics of newly developed soy cultivars in growth chamber. Ten soy cultivars evaluated in three [CO2] levels (CD1, 350; CD2, 500; CD3, 700ppm) and three water content (WC1: 30%, WC2: 40, WC3: 50%) in the pot in growth chamber. Increased [CO2] from 350 to 500 and 500 to 700ppm enhanced crop growth parameters greatly and grain yield, however, grown in CD3 enhanced plant height increasing speed, and shortened growing duration, however, they were grow very weakly and it resulted in lodging problem. High soil water content (WC3) hampered growth and yield of soybean in three CD treatments and the degree was lower in CD1 and CD2 than CD3. In this results we can conclude increasing [CO2] in Korean peninsular might be decrease lodging resistance, especially high moisture content, so, plant breeders and physiologists need to develop improved lodging resistance cultivars under high water content and high CO2 content.