Heterosis is a quicker,cheaper and easier method for increasing plantation production,and heterosis studies can provide the basis for exploitation of valuable hybrid combinations in breeding programs.Growth traits,woo...Heterosis is a quicker,cheaper and easier method for increasing plantation production,and heterosis studies can provide the basis for exploitation of valuable hybrid combinations in breeding programs.Growth traits,wood properties,and bark percentage were assessed for 6×6 full diallel progenies of E.urophylla in southern China measured at age 4 years.Analysis of variance showed that there were significant differences on all studied traits except dynamic modulus of elasticity among combinations.The mean diameter at breast height,wood basic density,and dynamic modulus of elasticity were 9.40 to 12.20 cm,0.45 to 0.47 g cm-3,and 5.04 to 5.72 GPa,respectively.The coefficients of variation ranged from 18.18%to 50.43%for growth traits,9.07%to 55.24%for wood properties and 22.26%to 23.93%for bark percentage.The heterosis estimation on diameter at breast height,wood basic density,and dynamic modulus of elasticity were-24.07%to 18.74%,-14.23%to 9.17%and-25.53%to 16.28%.U22×U56 generally had higher heterosis of growth traits and wood properties through three sites.Same combinations had different original and reciprocal heterosis estimation at two sites even on same traits.The combinations of same parents always had similar original and reciprocal heterosis estimation.展开更多
Breeding is the major procedure in forest research.The basic goal in all of breeding program is to expand the frequency of favorable alleles or the frequency of specific combinations of favorable alleles in the breedi...Breeding is the major procedure in forest research.The basic goal in all of breeding program is to expand the frequency of favorable alleles or the frequency of specific combinations of favorable alleles in the breeding populations through recurrent selection in order to improve the performance of individual plants.During the past three decades,an increase in research on breeding has improved Eucalyptus productivity,and to some extent our standing of their effects on tree growth and on wood properties.Unfortunately,very little information about breeding on the review of Eucalyptus grown in China has been published even though this species was introduced some 120 years ago.This paper reviews the available information regarding research status and prospect of breeding under Chinese ecological conditions and to outline some suggestions to them.According to the present research situation of breeding,we would recommend that:generalizing empirical and useful practices;developing highvalue products;creating more clones for demand;carrying out intensively research over different species and clones for different cultivation goals at different sites over time;above all,applying breeding strategy,especially for multiple generations and interspecific hybrid breeding.展开更多
Growth traits and wood properties were assessed for DH32-29,a clone of Eucalyptus urophylla×E.grandis,at the age of two to six in Guangdong,China.Analysis of variance of studied traits showed that there were sign...Growth traits and wood properties were assessed for DH32-29,a clone of Eucalyptus urophylla×E.grandis,at the age of two to six in Guangdong,China.Analysis of variance of studied traits showed that there were significant differences(1%level)on Fiber Length and Fiber Width among ages,with F value ranging from 12.73 to 18.91,indicating clear differences between ages.The Fiber Length increased from 0.58 mm at 2-year to 0.60 mm at 3-year,061 mm at 4-year,0.72 mm at 5-year and 0.79 mm at 6-year,meanwhile the annual Fiber Length increment among ages increased from 0.02 to 0.01,0.11 and 0.07 mm,respectively.However,Mean Curl,Kink Index and Kink Angle were not found any trend by age.In general,the correlations between same traits were different with different ages.The biggest negative correlations(-0.78)was found between Fiber Length and Fine Percentage at 4-year while the biggest positive correlations(0.98)was found between Kink Index and Kink Angle at 2-year and 4-year.展开更多
文摘Heterosis is a quicker,cheaper and easier method for increasing plantation production,and heterosis studies can provide the basis for exploitation of valuable hybrid combinations in breeding programs.Growth traits,wood properties,and bark percentage were assessed for 6×6 full diallel progenies of E.urophylla in southern China measured at age 4 years.Analysis of variance showed that there were significant differences on all studied traits except dynamic modulus of elasticity among combinations.The mean diameter at breast height,wood basic density,and dynamic modulus of elasticity were 9.40 to 12.20 cm,0.45 to 0.47 g cm-3,and 5.04 to 5.72 GPa,respectively.The coefficients of variation ranged from 18.18%to 50.43%for growth traits,9.07%to 55.24%for wood properties and 22.26%to 23.93%for bark percentage.The heterosis estimation on diameter at breast height,wood basic density,and dynamic modulus of elasticity were-24.07%to 18.74%,-14.23%to 9.17%and-25.53%to 16.28%.U22×U56 generally had higher heterosis of growth traits and wood properties through three sites.Same combinations had different original and reciprocal heterosis estimation at two sites even on same traits.The combinations of same parents always had similar original and reciprocal heterosis estimation.
文摘Breeding is the major procedure in forest research.The basic goal in all of breeding program is to expand the frequency of favorable alleles or the frequency of specific combinations of favorable alleles in the breeding populations through recurrent selection in order to improve the performance of individual plants.During the past three decades,an increase in research on breeding has improved Eucalyptus productivity,and to some extent our standing of their effects on tree growth and on wood properties.Unfortunately,very little information about breeding on the review of Eucalyptus grown in China has been published even though this species was introduced some 120 years ago.This paper reviews the available information regarding research status and prospect of breeding under Chinese ecological conditions and to outline some suggestions to them.According to the present research situation of breeding,we would recommend that:generalizing empirical and useful practices;developing highvalue products;creating more clones for demand;carrying out intensively research over different species and clones for different cultivation goals at different sites over time;above all,applying breeding strategy,especially for multiple generations and interspecific hybrid breeding.
文摘Growth traits and wood properties were assessed for DH32-29,a clone of Eucalyptus urophylla×E.grandis,at the age of two to six in Guangdong,China.Analysis of variance of studied traits showed that there were significant differences(1%level)on Fiber Length and Fiber Width among ages,with F value ranging from 12.73 to 18.91,indicating clear differences between ages.The Fiber Length increased from 0.58 mm at 2-year to 0.60 mm at 3-year,061 mm at 4-year,0.72 mm at 5-year and 0.79 mm at 6-year,meanwhile the annual Fiber Length increment among ages increased from 0.02 to 0.01,0.11 and 0.07 mm,respectively.However,Mean Curl,Kink Index and Kink Angle were not found any trend by age.In general,the correlations between same traits were different with different ages.The biggest negative correlations(-0.78)was found between Fiber Length and Fine Percentage at 4-year while the biggest positive correlations(0.98)was found between Kink Index and Kink Angle at 2-year and 4-year.
