Abstract
The nitrogen fixation activity and environmental factors of Lespedeza bicli!oy Turcz, forming annual root nodules by symbiotic Rhizobium sp. were analyzed in the field conditions during the growing period. Seasunal changes of $N_2-fixation$ activity showed the maximum value of $120\;\mu\textrm{M}\;C_2_H4{\cdot}noduie\;g\;fw^{-1}{\cdot}hr^{-1}$ during the active growing period (June) and varied significantly depending on the growth phase and environmental factors. The maximum activities were attained at the conditions of pH 7, $30^{\circ}C$ of temperature, 18 Kpa of oxygen partial pressure and inhibited by water stress and nitrogen sources. The habitat soil was weak acidic and poor in nitrogen, phosphorus and organic matter contents. The leaf area ratios and chlorophyll contents were ranged from 442 to $48;\textrm{cm}^2{\cdot}g\;dw^{-1}$ and from 33 to $38\;\mu\textrm{g}\;chI{\cdot}\textrm{cm}^2$. Nitrogen contents in each organ showed the maximum of 46, 19 and $11\;mg{\cdot}g\;dw^{-1}, respectively for leaf, rool and stem in the early period. The highest phosphorus contents were 4.2, 1.2 and $0.6\;mg{\cdot}g\;dw^{-1}$, respectively for leaf. root and stem in early growing period. The allocation ratios of nitrogen quantity showed 60% for leaves and 73% for roots during the active and late growth period, and 22% [or stems in average. The allocalion ralios o[ phosphorus quantity showed 58% for leaves during the most productive period, 70% for roots in the pre-growth stage and 26% for stems in average.verage.
형제봉 서쪽 사면에 소나무와 혼생하는 싸리군집의 생육기간중 공생근류의 질소고정활성의 계절변화와 환경요인의 특성을 분석하였다. 근류는 1년생으로서 그 활성은 최대생장기인 6월중에 최대치 $120\;\mu\textrm{M}\;C_2H_2{\cdot}nodule\;g\;fw^{-1}{\cdot}hr^{-1}$이었고, 생육휴지기에는 활성이 소실되었다. 질소고정활성에 대한 최적의 pH, 온도 및 산소농도는 각각 중성, $30^{\circ}C$ 및 18 Kpa $O_2$의 호기상태였으며, 토양수분의 stress는 1.5 Mpa에서 56%의 활성감소를 보였으며, ${NO_3}^{-}와\;{NH_4}^{+}$ 1 mM 처리는 각각 85%와 12%의 활성저해를 보였다. 토양환경은 약산성으로 질소, 인 및 유기물함량이 빈약하였고 잎의 엽면적과 엽록소함량은 각각 $440-483\;\textrm{cm}^2{\cdot}g^{-1}와\;33-32\;$\mu\textrm{g}\;chl{\cdot}g^{-1}$이었다. 잎, 뿌리 및 줄기의 질소함량은 각각 46, 19 및 $11\;mgN{\cdot}g\;dw^{-1}$, 인은 4.2, 1.2 및 $0.6\;mg{\cdot}g\;dw^{-1}$이었고, 각 기관별 질소와 인의 분배율은 잎에서 60, 59%, 뿌리에 73, 70% 그리고 줄기에 22, 26%이었다.