为了探究冀西北坝上地区白榆的光合生理特性,明确影响白榆光合作用的主要生理生态因子,以白榆(Ulmus pumila)人工纯林为研究对象,利用Li-6400XT便携式光合分析仪测定自然光照条件下白榆叶片的光合生理指标,同时测定气象因子、土壤体积...为了探究冀西北坝上地区白榆的光合生理特性,明确影响白榆光合作用的主要生理生态因子,以白榆(Ulmus pumila)人工纯林为研究对象,利用Li-6400XT便携式光合分析仪测定自然光照条件下白榆叶片的光合生理指标,同时测定气象因子、土壤体积含水率(SWC)及白榆根系的分布,分析各生理生态因子对白榆光合生理指标的影响。结果表明:(1)6:00~18:00,白榆净光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))和气孔限制值(L_(s))日变化趋势呈先上升后下降的“单峰”曲线,胞间CO_(2)浓度(C_(i))日变化趋势呈先下降后上升的“谷型”曲线,水分利用效率(WUE)日变化呈下降趋势。(2)白榆P_(n)的日变化受气孔限制和非气孔限制的共同作用,在8:00~14:00受非气孔限制,其他时段则受气孔限制。(3)白榆P_(n)与G_(ms)、空气湿度(RH)呈极显著正相关关系(P<0.01),与叶片饱和水汽压差(VPD)、100~150 cm SWC呈极显著负相关关系,与0~20 cm SWC呈极显著正相关关系(P<0.05),与40~70 cm SWC呈显著负相关关系。(4)白榆根系在0~200 cm均有分布,但出现浅层化现象,其细根生物量主要集中在0~20 cm土层,粗根主要分布在20~40 cm土层。综上,冀西北坝上地区白榆光合作用日变化主要受G_(s)、RH、SWC的影响,随表层土壤水分变化一致。展开更多
Through Ulmus pumila cv.’Jinye’ container-growing seedling cultivation experiment with 4 types of media or 9 media formulas,the seedling height,the stem and crown diameter indexes of U.pumila cv.jinye were measured....Through Ulmus pumila cv.’Jinye’ container-growing seedling cultivation experiment with 4 types of media or 9 media formulas,the seedling height,the stem and crown diameter indexes of U.pumila cv.jinye were measured.These indexes were significantly or extreme significantly different among various media.The growth of seedling root system varied with different media.The rooting and root number in soft media were much better than that in dense media.According to the growth traits of above-ground and underground parts of U.pumila cv.jinye seedlings,the medium suitable for U.pumila cv.jinye seedling growth was defined as media type I,whose ratio of C/N was 17.7—18.1,the density was higher than 0.26 g·cm-3.Grown on this medium,the height,stem diameter and crown diameter of U.pumila cv.jiny were 1.34—1.57 m,1.36—1.50 cm and 59.6—73.9 cm,respectively.The results of experiment showed also that the physical property played an active role in cultural media,so a good initial medium could provide great assistance of fertilization and water management in seedling culture.展开更多
文摘为了探究冀西北坝上地区白榆的光合生理特性,明确影响白榆光合作用的主要生理生态因子,以白榆(Ulmus pumila)人工纯林为研究对象,利用Li-6400XT便携式光合分析仪测定自然光照条件下白榆叶片的光合生理指标,同时测定气象因子、土壤体积含水率(SWC)及白榆根系的分布,分析各生理生态因子对白榆光合生理指标的影响。结果表明:(1)6:00~18:00,白榆净光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))和气孔限制值(L_(s))日变化趋势呈先上升后下降的“单峰”曲线,胞间CO_(2)浓度(C_(i))日变化趋势呈先下降后上升的“谷型”曲线,水分利用效率(WUE)日变化呈下降趋势。(2)白榆P_(n)的日变化受气孔限制和非气孔限制的共同作用,在8:00~14:00受非气孔限制,其他时段则受气孔限制。(3)白榆P_(n)与G_(ms)、空气湿度(RH)呈极显著正相关关系(P<0.01),与叶片饱和水汽压差(VPD)、100~150 cm SWC呈极显著负相关关系,与0~20 cm SWC呈极显著正相关关系(P<0.05),与40~70 cm SWC呈显著负相关关系。(4)白榆根系在0~200 cm均有分布,但出现浅层化现象,其细根生物量主要集中在0~20 cm土层,粗根主要分布在20~40 cm土层。综上,冀西北坝上地区白榆光合作用日变化主要受G_(s)、RH、SWC的影响,随表层土壤水分变化一致。
文摘Through Ulmus pumila cv.’Jinye’ container-growing seedling cultivation experiment with 4 types of media or 9 media formulas,the seedling height,the stem and crown diameter indexes of U.pumila cv.jinye were measured.These indexes were significantly or extreme significantly different among various media.The growth of seedling root system varied with different media.The rooting and root number in soft media were much better than that in dense media.According to the growth traits of above-ground and underground parts of U.pumila cv.jinye seedlings,the medium suitable for U.pumila cv.jinye seedling growth was defined as media type I,whose ratio of C/N was 17.7—18.1,the density was higher than 0.26 g·cm-3.Grown on this medium,the height,stem diameter and crown diameter of U.pumila cv.jiny were 1.34—1.57 m,1.36—1.50 cm and 59.6—73.9 cm,respectively.The results of experiment showed also that the physical property played an active role in cultural media,so a good initial medium could provide great assistance of fertilization and water management in seedling culture.
