【摘要】 为探究连香树(Cercidiphyllum japonicum)幼苗的需光特性和对光环境变化的适应性，以及确定其最佳生长光照环境，采用1年生连香树为试验材料，设置遮阴度为80%、65%、50%、35%和0%(全光照)的5种光环境，观测5种遮阴度下连香树幼苗生长、叶片形态、生物量和不同器官碳(C)、氮(N)、磷(P)含量及其化学计量特征的变化。结果表明，连香树幼苗生长、生物量、根系发育、元素含量和积累量及化学计量比均受到外界光照强度的显著影响(P<0.05)。随着遮阴度的增加，苗高、叶长、叶宽、单叶叶面积、叶片含水量和根系形态6个指标均呈现先增加后下降的趋势，地径和比叶面积则逐渐增加，而比叶重减少。遮阴处理的叶长、叶宽、单叶叶面积、叶片含水量和比叶面积均高于全光照，而比叶重则低于全光照。总生物量在65%遮阴下最大，在80%遮阴下最小。遮阴处理的根和叶C含量低于全光照，而茎高于全光照，根、茎和叶的N含量均高于全光照，茎和叶的P含量均低于全光照。随着遮阴度的增加，C积累量逐渐降低，在35%遮阴下达到最大值，N积累量则逐渐增加，在80%遮阴下达到最大值，P积累量则呈现先降低后增加的变化，且在全光照下含量最高。连香树幼苗C∶N和C∶P随遮阴度变大均呈现出先增加后减小的变化趋势，遮阴度为50%下均达最大值。连香树各器官N∶P范围在3.1～12.5,均小于14,说明在不同遮阴条件下连香树幼苗的生长主要受N限制。综上所述，遮阴改变连香树幼苗不同器官的C、N、P含量与分配，进而影响其生长、根系发育和生物量分配。连香树苗期培育可适当进行遮阴，遮阴度在50%左右有助于幼苗生长、生物量、养分含量和积累量的增加，而过度遮阴则会抑制幼苗生长发育。更多还原

【Abstract】 To investigate the light demand and adaptability to light environment of Cercidiphyllum japonicum seedlings to determine their optimal growth light environment, 1-year-old Cercidiphyllum japonicum was used as experimental materials, 5 lighting environments with natural light and shade levels of 80%, 65%, 50% and 35% were set, and the changes of growth, leaf morphology, biomass, C, N and P contents of different organs and their stoichiometric characteristics of Cercidiphyllum japonicum seedlings under 5 shading levels were observed. The results showed that the seedling growth, biomass, root development, elemental contents and accumulation, and stoichiometric ratio of Cercidiphyllum japonicum seedling were significantly affected by external light intensity(P<0.05). As the shading levels increased, the 6 indexes of seedling height, leaf length, leaf width, single leaf area, leaf water content and root morphology showed a trend of first increasing and then decreasing. The ground diameter and specific leaf area increased gradually, while the specific leaf weight decreased. The leaf length, leaf width, single leaf area, leaf water content, and specific leaf area with shading treatment were all higher than those with full light, while the specific leaf weight was lower than that with full light. The total biomass was the highest at 65% shading and the lowest at 80% shading. The C content of roots and leaves with shading treatment was lower than that with full light, while stems were higher than that with full light. The N content of roots, stems and leaves was high-er than that with full light, and the P content of stems and leaves was lower than that with full light. As the shading degree increased, the accumulation of C gradually decreased, reaching the maximum value at 35% shading, while the accumulation of N gradually in-creased, reaching the maximum values at 80% shading, and the accumulation of P showed a trend of first decreasing and then increas-ing, with the highest content with full sunlight. The C ∶ N and C ∶ P of Cercidiphyllum japonicum seedlings showed a trend of first in-creasing and then decreasing with the increasing of shading levels, reaching the maximum values at 50% shading levels. The N ∶ P of each organs of Cercidiphyllum japonicum was between 3. 1 and 12. 5, which was less than 14, indicating the growth of Cercidiphyllum japonicum seedlings was mainly limited by N with different shading conditions. In conclusion, shading changed the content and distri-bution of C, N and P in different organs of Cercidiphyllum japonicum seedlings, and then affected their growth, root development, and biomass distribution. During the cultivation of Cercidiphyllum japonicum seeding, appropriate shading could be applied. A shade level of about 50% could help increase of seedling growth, biomass, nutrient content and accumulation, while excessive shading could inhib-it the seedling growth and development.更多还原