为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨...为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨树为对照,研究不同强度修枝对10年生毛白杨生长和生理特性的影响。结果表明:对于10年生中高龄杨树,修枝对树高、胸径、材积增长率无显著影响,但重度修枝能提高剩余叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s)),增强单叶水平上物质合成的能力,而修枝对瞬时水分利用效率(WUE)影响不显著。从生长和光合角度综合分析,修去树冠下部1/2枝条能够改善10年生毛白杨生理状况,但对林木生长无明显促进作用。展开更多
In Hebei Province of North China, forest was recovered with natural recruitment in plantations with large area of clear-cutting Chinese pine（Pinus tabuliformis）. This study was aimed to demonstrate the dynamic chara...In Hebei Province of North China, forest was recovered with natural recruitment in plantations with large area of clear-cutting Chinese pine（Pinus tabuliformis）. This study was aimed to demonstrate the dynamic characteristics of recruits during the natural recruitment. Both plot survey and the spatial point-pattern analysis were performed. Five developmental stages of natural recruitment were selected and studied, including 1 year before and 2, 5, 8, and 11 years after clear-cutting. Different slope aspects were also included. Natural recruitment was always dominated by Chinese pine with a proportion of higher than 90%. For plots of 1 year before clear-cutting on east-and north-facing slopes, recruit densities were 7886 and 5036 stems/hm2, the average heights were 0.78（±0.85） and 1.06（±1.15） m, and the average diameters at breast height（DBH） were 3.21（±1.38） and 2.91（±1.38） cm, respectively. After clear-cutting, recruit density was initially increased, then it was gradually declined with time; however, the variation of average DBH was contrary to that of recruit density. Both of them were no longer varied between 8 and 11 years after clear-cutting. The average height of recruits continued to increase after clear-cutting. For the plots of 11 years after clear-cutting on east-and north-facing slopes, average heights of recruits reached 2.00（±1.14） and 2.24（±1.20） m, respectively. The statuses of recruits on north-facing slopes were better than those on east-facing slopes after clear-cutting. Meanwhile, recruits on east-facing slopes were always aggregated at small scales, while spatial pattern of recruits varied with time on north-facing slopes. Moreover, forest was recovered more quickly by natural recruitment than by artificial afforestation after clear-cutting. The structural diversity was higher in naturally regenerated forests than in plantations of the same age. Our results demonstrated that clear-cutting of Chinese pine plantations recovered by natural recruitment has the potential to be an effective approach for establishing multifunctional forest.展开更多
In order to select a suitable genotype for the studies on genetic transformation, the difference among three genotypes (DN04-18, DN04-25 and DN04-26) of Populus × euramericana (Populus deltoides × P. nigra) ...In order to select a suitable genotype for the studies on genetic transformation, the difference among three genotypes (DN04-18, DN04-25 and DN04-26) of Populus × euramericana (Populus deltoides × P. nigra) in terms of shoot regeneration was investigated in this paper. An efficient in vitro micropropagation method was successfully established for genotype DN04-18. The high frequency shoot regeneration (90.0%) from leaf discs was obtained in genotype DN04-18 on the modified Murashige and Skoog (mMS) medium with 30 g/L sucrose and 5.5 g/L agar (pH: 5.8) which was supplemented with 0.8 mg/L 6-benzyladenine (6-BA), while the shoot regeneration rates of DN04-25 and DN04-26 were below 40.0% even on the same medium. The optimum rooting medium was 1/2 mMS medium supplemented with 0.3-0.4 mg/L indole-3-butyric acid (IBA) for three genotypes. The results showed that genotype is a key factor for restricting shoot regeneration in establishing regeneration system of P. × euramerican hybrids. This micropropagation system of DN04-18 is expected to be suitable for the studies on gene transformation to improve drought tolerance of P. × euramerican.展开更多
文摘为探讨中高林龄杨树(Populus)光合生理特性对不同修枝强度的响应规律,以10年生三倍体毛白杨(triploid Populus tomentosa)无性系B301与S86为研究对象,采用轻度修枝(修去树冠下部1/3枝条)和重度修枝(修去树冠下部1/2枝条),以及未修枝杨树为对照,研究不同强度修枝对10年生毛白杨生长和生理特性的影响。结果表明:对于10年生中高龄杨树,修枝对树高、胸径、材积增长率无显著影响,但重度修枝能提高剩余叶片的净光合速率(P_(n))、蒸腾速率(T_(r))、气孔导度(G_(s)),增强单叶水平上物质合成的能力,而修枝对瞬时水分利用效率(WUE)影响不显著。从生长和光合角度综合分析,修去树冠下部1/2枝条能够改善10年生毛白杨生理状况,但对林木生长无明显促进作用。
基金supported by the National Key R&D Program of China (2017YFD0600501)the Fundamental Research Funds for the Central Universities of China (TD2011-08)
文摘In Hebei Province of North China, forest was recovered with natural recruitment in plantations with large area of clear-cutting Chinese pine（Pinus tabuliformis）. This study was aimed to demonstrate the dynamic characteristics of recruits during the natural recruitment. Both plot survey and the spatial point-pattern analysis were performed. Five developmental stages of natural recruitment were selected and studied, including 1 year before and 2, 5, 8, and 11 years after clear-cutting. Different slope aspects were also included. Natural recruitment was always dominated by Chinese pine with a proportion of higher than 90%. For plots of 1 year before clear-cutting on east-and north-facing slopes, recruit densities were 7886 and 5036 stems/hm2, the average heights were 0.78（±0.85） and 1.06（±1.15） m, and the average diameters at breast height（DBH） were 3.21（±1.38） and 2.91（±1.38） cm, respectively. After clear-cutting, recruit density was initially increased, then it was gradually declined with time; however, the variation of average DBH was contrary to that of recruit density. Both of them were no longer varied between 8 and 11 years after clear-cutting. The average height of recruits continued to increase after clear-cutting. For the plots of 11 years after clear-cutting on east-and north-facing slopes, average heights of recruits reached 2.00（±1.14） and 2.24（±1.20） m, respectively. The statuses of recruits on north-facing slopes were better than those on east-facing slopes after clear-cutting. Meanwhile, recruits on east-facing slopes were always aggregated at small scales, while spatial pattern of recruits varied with time on north-facing slopes. Moreover, forest was recovered more quickly by natural recruitment than by artificial afforestation after clear-cutting. The structural diversity was higher in naturally regenerated forests than in plantations of the same age. Our results demonstrated that clear-cutting of Chinese pine plantations recovered by natural recruitment has the potential to be an effective approach for establishing multifunctional forest.
文摘In order to select a suitable genotype for the studies on genetic transformation, the difference among three genotypes (DN04-18, DN04-25 and DN04-26) of Populus × euramericana (Populus deltoides × P. nigra) in terms of shoot regeneration was investigated in this paper. An efficient in vitro micropropagation method was successfully established for genotype DN04-18. The high frequency shoot regeneration (90.0%) from leaf discs was obtained in genotype DN04-18 on the modified Murashige and Skoog (mMS) medium with 30 g/L sucrose and 5.5 g/L agar (pH: 5.8) which was supplemented with 0.8 mg/L 6-benzyladenine (6-BA), while the shoot regeneration rates of DN04-25 and DN04-26 were below 40.0% even on the same medium. The optimum rooting medium was 1/2 mMS medium supplemented with 0.3-0.4 mg/L indole-3-butyric acid (IBA) for three genotypes. The results showed that genotype is a key factor for restricting shoot regeneration in establishing regeneration system of P. × euramerican hybrids. This micropropagation system of DN04-18 is expected to be suitable for the studies on gene transformation to improve drought tolerance of P. × euramerican.
