Bud flushing is very important for the survival and growth of trees, a phenomenon matched each year with the annual course of temperature and the timing of bud flushing in the spring. Essentially it represents a serio...Bud flushing is very important for the survival and growth of trees, a phenomenon matched each year with the annual course of temperature and the timing of bud flushing in the spring. Essentially it represents a serious ecological and evolutionary tradeoff between survival and growth. The most suitable timing of bud burst permits trees to begin growth sufficiently early to take advantage of favorable spring conditions, but late enough to decrease the risks of tissue damage from late frost. In the present study bud burst spring phenology of poplar （Populus tremula and P. tremuloides） from eight different provenances, originating from Eu- rope and the USA, was observed during March and April, 2009. The experimental plot was located at Solling, Germany （51~44＇0＂ N, 9036＇0＇＇ E）. A six stage subjective scoring system of bud burst phenology was used to identify the phenological stages of the seed- lings, where each plant was observed twice a week. The aim of the study was to predict phenotypic variation in poplar, originating from regions between 42~ and 60~ N latitude, growing in similar environments. Timing of bud flushing of poplar was recorded. It was found that seedlings of provenance 3, which originated from 42.35~ N latitude, started and completed flushing significantly earlier than those of other provenances, while seedlings of provenance 5, originating from 54.29~ N latitude, started flushing very late and only a few plants reached top scoring at the end of the experimental period. Analysis of variance showed statistically highly signifi- cant differences （p 〈 0.05） in bud flushing among the provenances. The correlation between scoring and flushing periods was very strong within provenances although the flushing pattern differed among provenances （origin of the planted seedlings）. Bud flushing showed a negative correlation with the origin of the planted seedlings. Given the field experience gained with this experiment, it is recommended that seedlings from provenances 5 and 8 could be used for future plantations where late frost may be a problem for the young shoots of seedlings.展开更多
High potential productivity together with short rotation periods have made hybrid aspen an interesting option for wood production on former arable land in Nordic countries.In this study,some of the oldest active exper...High potential productivity together with short rotation periods have made hybrid aspen an interesting option for wood production on former arable land in Nordic countries.In this study,some of the oldest active experimental plots with hybrid aspen in Sweden were remeasured at 23–30 years of age.A main aim was to assess age and productivity at the time of maximum mean annual volume increment.In addition,the infl uence of commercial thinning on stand development and diff erences in genetic gain among clones were investigated.Data from fi ve experiments in southern Sweden were used,including three genetic trials,one demonstration stand with a clone mixture and one stand regenerated from root suckers.The three genetic trials were treated as single plot experiments,subject to a standard thinning program.In the remaining experiments,diff erent thinning strategies were tested in a balanced block design.Volume growth had culminated or was close to maximum at age 25–30 years.Mean annual stem volume increment at culmination was 20–22 m 3 ha^−1 a^−1.Dominant height reached 30–35 m at 28–30 years of age.Mean diameter at breast height was 27–29 cm after 29–30 years in the genetic trials.Clonal ranking based on diameter at age 7–9 years was positively correlated with the ranking at the fi nal measurement in the genetic trials,20 years later.This indicates that clones can be selected for superior growth based on results from young trials.More intense thinning programs increased the mean diameter compared to light thinning.The study indicates that one or two early and relatively heavy thinnings can promote the development of crop trees,without jeopardizing total volume production during a rotation of 25–30 years.展开更多
In this study, the vitrificated plants of hybrid aspen (Populus tremula× P.tremuloides) by micropropagation were used as the materials,and ELISA method was adopted to measure the content of endogenous plant hormo...In this study, the vitrificated plants of hybrid aspen (Populus tremula× P.tremuloides) by micropropagation were used as the materials,and ELISA method was adopted to measure the content of endogenous plant hormones in the plants. At the same time, the factors that influenced the vitrification of the plant as well as de-vitrification method were also studied by changing medium’s component, which was to provide useful information for commercial propagation of good hybrid clones of aspen. The results were as follows: 1)The ABA and IAA contents in the vitrificated plants were higher than those in the non-vitrificated plants obviously, and the GA content was little lower than that of the non-vitrificated plants. Therefore, the higher IAA or ABA content in the vitrificated plants was possibly the main reason for the vitrification of the plant.2)The ratios of endogenous plant hormones such as ABA/GA and IAA/GA in the vitrificated plants of hybrid aspen by tissue culture were higher than those in the non-vitrificated plants, which indicated that the equilibrium relationship among different endogenous hormones in vitrificated plants was deviated from the normal, then possibly resulting in the vitrification of the plant.展开更多
基金supported by the Institute of Forest Genetics and Forest Tree Breedingthe Institute of Forest Botany, Georg-August-University, Gttingen,Germanyprovided by the university and a scholarship from the European Union
文摘Bud flushing is very important for the survival and growth of trees, a phenomenon matched each year with the annual course of temperature and the timing of bud flushing in the spring. Essentially it represents a serious ecological and evolutionary tradeoff between survival and growth. The most suitable timing of bud burst permits trees to begin growth sufficiently early to take advantage of favorable spring conditions, but late enough to decrease the risks of tissue damage from late frost. In the present study bud burst spring phenology of poplar （Populus tremula and P. tremuloides） from eight different provenances, originating from Eu- rope and the USA, was observed during March and April, 2009. The experimental plot was located at Solling, Germany （51~44＇0＂ N, 9036＇0＇＇ E）. A six stage subjective scoring system of bud burst phenology was used to identify the phenological stages of the seed- lings, where each plant was observed twice a week. The aim of the study was to predict phenotypic variation in poplar, originating from regions between 42~ and 60~ N latitude, growing in similar environments. Timing of bud flushing of poplar was recorded. It was found that seedlings of provenance 3, which originated from 42.35~ N latitude, started and completed flushing significantly earlier than those of other provenances, while seedlings of provenance 5, originating from 54.29~ N latitude, started flushing very late and only a few plants reached top scoring at the end of the experimental period. Analysis of variance showed statistically highly signifi- cant differences （p 〈 0.05） in bud flushing among the provenances. The correlation between scoring and flushing periods was very strong within provenances although the flushing pattern differed among provenances （origin of the planted seedlings）. Bud flushing showed a negative correlation with the origin of the planted seedlings. Given the field experience gained with this experiment, it is recommended that seedlings from provenances 5 and 8 could be used for future plantations where late frost may be a problem for the young shoots of seedlings.
文摘High potential productivity together with short rotation periods have made hybrid aspen an interesting option for wood production on former arable land in Nordic countries.In this study,some of the oldest active experimental plots with hybrid aspen in Sweden were remeasured at 23–30 years of age.A main aim was to assess age and productivity at the time of maximum mean annual volume increment.In addition,the infl uence of commercial thinning on stand development and diff erences in genetic gain among clones were investigated.Data from fi ve experiments in southern Sweden were used,including three genetic trials,one demonstration stand with a clone mixture and one stand regenerated from root suckers.The three genetic trials were treated as single plot experiments,subject to a standard thinning program.In the remaining experiments,diff erent thinning strategies were tested in a balanced block design.Volume growth had culminated or was close to maximum at age 25–30 years.Mean annual stem volume increment at culmination was 20–22 m 3 ha^−1 a^−1.Dominant height reached 30–35 m at 28–30 years of age.Mean diameter at breast height was 27–29 cm after 29–30 years in the genetic trials.Clonal ranking based on diameter at age 7–9 years was positively correlated with the ranking at the fi nal measurement in the genetic trials,20 years later.This indicates that clones can be selected for superior growth based on results from young trials.More intense thinning programs increased the mean diameter compared to light thinning.The study indicates that one or two early and relatively heavy thinnings can promote the development of crop trees,without jeopardizing total volume production during a rotation of 25–30 years.
文摘In this study, the vitrificated plants of hybrid aspen (Populus tremula× P.tremuloides) by micropropagation were used as the materials,and ELISA method was adopted to measure the content of endogenous plant hormones in the plants. At the same time, the factors that influenced the vitrification of the plant as well as de-vitrification method were also studied by changing medium’s component, which was to provide useful information for commercial propagation of good hybrid clones of aspen. The results were as follows: 1)The ABA and IAA contents in the vitrificated plants were higher than those in the non-vitrificated plants obviously, and the GA content was little lower than that of the non-vitrificated plants. Therefore, the higher IAA or ABA content in the vitrificated plants was possibly the main reason for the vitrification of the plant.2)The ratios of endogenous plant hormones such as ABA/GA and IAA/GA in the vitrificated plants of hybrid aspen by tissue culture were higher than those in the non-vitrificated plants, which indicated that the equilibrium relationship among different endogenous hormones in vitrificated plants was deviated from the normal, then possibly resulting in the vitrification of the plant.
