论文部分内容阅读
Abstract Growth traits of semisib families of Pinus elliottii were studied. The results showed that there were extremely significant differences between the P. elliottii families in terms of tree height， DBH and volume （P<0.01）， and the families could be selected effectively. Both family heritability and single plant heritability of growth traits of P. elliottii were high. The family heritability of tree height， DBH and volume was 0.799， 0.779 and 0.770 respectively， and their single plant heritability was 0.683， 0.829 and 0.742 respectively. Among them， the family heritability of tree height was the highest， while the single plant heritability of DBH was the highest. The Duncan analysis of growth traits of the P. elliottii families revealed that families 12， 7， 15， 4 and 6 were superior families and can be used as highyield families.
Key words Pinus elliottii; Semisib families; Growth traits; Heritability
Pinus elliottii is native to the southeastern United States. It has become an excellent pulpwood， building wood and resin taping tree because of its wide adaptability， fast growth， good material property， good resin quality and high yield[1-3]， and it has been widely planted in southern China. In this study， according to the research status and social needs of breeding of highyield P. elliottii in China[4-7]， the growth traits and selection of halfsib families of P. elliottii were studied， which is of great significance for the construction of fastgrowing and highyielding forest of P. elliottii.
Materials and Methods
General situation of the test site
The test site （110°59′-111°34′ E，26°07′-26°52′ N） is located in Dongan County， Yongzhou City， Hunan Province. It has a typical subtropical monsoon humid climate， with abundant sunshine， abundant rainfall， a warm and humid climate， four distinct seasons， and features such as "changeable temperature in spring， frequent cold current， rich heat， long frostfree period， and frequent drought in summer and autumn". Here annual average temperature is 17.8 ℃， and the absolute maximum temperature is 39.9 ℃， while the absolute minimum temperature is -11.4 ℃. Annual average rainfall is 1 390.6 mm， and annual average relative humidity is 81%. Sunshine hours are 1 755.8 h， and annual frostfree period is 270 d. The landform of the test site is low hilly area， and terrain is gentle. Elevation is 200 m， and slope is 15-20°. The soil is sandstone red soil， and soil depth is more than 60 cm， while pH is 5.6-6.8. Soil texture is relatively sticky， and soil fertility is medium. Organic matter content is 0.6%-2.0%， and total nitrogen content is 0.1%-1.0%. Test materials
The test materials were provided by the research team of P. elliottii of Hunan Academy of Forestry （taken from the national P. elliottii improved variety base of Taolin national forest farm in Miluo City， Hunan Province）. A total of 13 P. elliottii families participated in the test （of which 6 families were national or provincial improved varieties）.
Test methods
Afforestation test was set in March 2006， in which completely randomized block design was adopted. There were four plants in each row and three repetitions. The growth indicators of the 13 families was observed at the end of 2015， including tree height， diameter at breast height （DBH） and volume of timber.
Data statistics and analysis
Tree height， DBH and volume are indicators of growth traits， and the volume was calculated using the approximate formula V=0.375×H×D 2. Statistical analysis of the measured data was performed using Excel and SPSS software. Family heritability （h 2F） and single plant heritability （h 2S） were calculated as follows：
h 2F=（MSF-MSFB）/MSF.
h 2S=4σ 2F/（σ 2E+σ 2FB+σ 2F）.
Results and Analysis
Analysis of differences between different families of P. elliottii in terms of growth traits
Among the 13 families， the average tree height of family 6 was the largest， up to 9.31 m. That of family 10 was the smallest， only 7.93 m. The coefficient of variation in the tree height of the 13 families was 1.38%-8.25%. The mean DBH of family 6 was the largest， reaching 14.49 cm. The mean DBH of family 5 was the smallest， only 12.17 cm. The coefficient of variation in the DBH of the 13 families ranged from 1.15% to 8.43%. The average volume of family 6 was the largest， up to 0.074 m 3， while that of family 5 was only 0.044 m 3. The coefficient of variation in the volume of the 13 families varied from 1.52% to 17.72% （Table 1）.
The variance analysis of growth traits of the P. elliottii families showed that the differences between different families in terms of tree height， DBH and volume were extremely significant （P<0.01）. It indicated that the variation of growth traits of P. elliottii was mainly from family differences， which lays a foundation for the selection of excellent families.
Analysis of heritability of growth traits of the P. elliottii families
Seen from Table 2， the family heritability of tree height， DBH and volume of P. elliottii was 0.799， 0.779 and 0.770 respectively， and their single plant heritability was 0.683， 0.829 and 0.742 respectively. It showed that the growth of tree height， DBH and volume were highly controlled by genetic effects， and efficient genetic selection of a single plant and families could be performed. Selection of superior families
Based on the above analysis， Duncan analysis of growth traits of the 13 families was carried out to select superior families with good growth traits. The 13 families were grouped using Duncans method. At the 0.05 significance level， families 9， 3， 7， 12， 15， 4 and 6 were classified as the group with the highest tree height， while families 10， 5， 14 and 1 were classified as the group with the lowest tree height， and it was lower than the average. Families 9， 12， 11， 7， 15， 4 and 6 were classified as the group with the largest DBH， while families 5， 10， 1， 2， 14 and 3 were classified as the group with the smallest DBH. The volume of families 12， 7， 15， 4 and 6 was larger than that of other families， while that of families 5， 10， 1， 14 and 2 was the smallest （Table 3， 4 and 5）. According to the growth traits of P. elliottii， families 12， 7， 15， 4 and 6 were superior families with excellent growth performances and can be used as highyield families.
Conclusions
（1）There were extremely significant differences between different families of P. elliottii in terms of tree height， DBH and volume （P<0.01）， and the families could be selected effectively.
（2）The family heritability and single plant heritability of growth traits of P. elliottii were high. The family heritability of tree height， DBH and volume of P. elliottii was 0.799， 0.779 and 0.770 respectively， and their single plant heritability was 0.683， 0.829 and 0.742 respectively. Among them， the family heritability of tree height was the highest， while the single plant heritability of DBH was the highest.
（3）According to the Duncan analysis of growth traits of the P. elliottii families， families 12， 7， 15， 4 and 6 were superior families and can be used as highyield families.
References
[1] WU JY， LONG YZ， YU GF， et al. Genetic analysis and combined selection of main economic characters of halfsib families for slash pine[J]. Scientia Silvae Sinicae， 2000， 36（z01）： 56-61. （in Chinese）.
[2] LI Y， PAN BH， HE HZ， et al. Study on selection of seedlings among halfsib families of Pinus elliottii[J]. Journal of Central South Forestry University， 2014， 34（3）： 86-89. （in Chinese）.
[3] WU JY，CHEN MG， LIU Q， et al. Seedling growth among halfsib and fullsib families of Pinus elliottii[J]. Journal of Central South Forestry University， 2016， 36（6）： 1-5， 10. （in Chinese）.
[4] WU JY， SUN JY， ZUO HS， et al. The high seed yield technology of Pinus elliottii seed orchard[J]. Hunan Forestry Science & Technology， 2011， 38（6）： 99-101. （in Chinese）.
[5] WU JY， LONG YZ， TONG FP， et al. Highyield growing techniques of seeds of Pinus elliottii firstgeneration high quality seed garden[J]. Hunan Forestry Science & Technology， 2002（4）：6-8. （in Chinese）.
[6] TONG FP， LIU ZH， WU JY， et al. Study on phosphate utilization efficiency of slash pines halfsib families[J]. Journal of Central South Forestry University， 2012， 32（12）： 154-157. （in Chinese）.
[7] WU JY， LI ZH， LONG YZ， et al. Genetic variation and selection of main economic characteristics of Slash pine fullsib family[J]. Journal of Central South Forestry University， 2010， 30（8）： 1-4. （in Chinese）.
Key words Pinus elliottii; Semisib families; Growth traits; Heritability
Pinus elliottii is native to the southeastern United States. It has become an excellent pulpwood， building wood and resin taping tree because of its wide adaptability， fast growth， good material property， good resin quality and high yield[1-3]， and it has been widely planted in southern China. In this study， according to the research status and social needs of breeding of highyield P. elliottii in China[4-7]， the growth traits and selection of halfsib families of P. elliottii were studied， which is of great significance for the construction of fastgrowing and highyielding forest of P. elliottii.
Materials and Methods
General situation of the test site
The test site （110°59′-111°34′ E，26°07′-26°52′ N） is located in Dongan County， Yongzhou City， Hunan Province. It has a typical subtropical monsoon humid climate， with abundant sunshine， abundant rainfall， a warm and humid climate， four distinct seasons， and features such as "changeable temperature in spring， frequent cold current， rich heat， long frostfree period， and frequent drought in summer and autumn". Here annual average temperature is 17.8 ℃， and the absolute maximum temperature is 39.9 ℃， while the absolute minimum temperature is -11.4 ℃. Annual average rainfall is 1 390.6 mm， and annual average relative humidity is 81%. Sunshine hours are 1 755.8 h， and annual frostfree period is 270 d. The landform of the test site is low hilly area， and terrain is gentle. Elevation is 200 m， and slope is 15-20°. The soil is sandstone red soil， and soil depth is more than 60 cm， while pH is 5.6-6.8. Soil texture is relatively sticky， and soil fertility is medium. Organic matter content is 0.6%-2.0%， and total nitrogen content is 0.1%-1.0%. Test materials
The test materials were provided by the research team of P. elliottii of Hunan Academy of Forestry （taken from the national P. elliottii improved variety base of Taolin national forest farm in Miluo City， Hunan Province）. A total of 13 P. elliottii families participated in the test （of which 6 families were national or provincial improved varieties）.
Test methods
Afforestation test was set in March 2006， in which completely randomized block design was adopted. There were four plants in each row and three repetitions. The growth indicators of the 13 families was observed at the end of 2015， including tree height， diameter at breast height （DBH） and volume of timber.
Data statistics and analysis
Tree height， DBH and volume are indicators of growth traits， and the volume was calculated using the approximate formula V=0.375×H×D 2. Statistical analysis of the measured data was performed using Excel and SPSS software. Family heritability （h 2F） and single plant heritability （h 2S） were calculated as follows：
h 2F=（MSF-MSFB）/MSF.
h 2S=4σ 2F/（σ 2E+σ 2FB+σ 2F）.
Results and Analysis
Analysis of differences between different families of P. elliottii in terms of growth traits
Among the 13 families， the average tree height of family 6 was the largest， up to 9.31 m. That of family 10 was the smallest， only 7.93 m. The coefficient of variation in the tree height of the 13 families was 1.38%-8.25%. The mean DBH of family 6 was the largest， reaching 14.49 cm. The mean DBH of family 5 was the smallest， only 12.17 cm. The coefficient of variation in the DBH of the 13 families ranged from 1.15% to 8.43%. The average volume of family 6 was the largest， up to 0.074 m 3， while that of family 5 was only 0.044 m 3. The coefficient of variation in the volume of the 13 families varied from 1.52% to 17.72% （Table 1）.
The variance analysis of growth traits of the P. elliottii families showed that the differences between different families in terms of tree height， DBH and volume were extremely significant （P<0.01）. It indicated that the variation of growth traits of P. elliottii was mainly from family differences， which lays a foundation for the selection of excellent families.
Analysis of heritability of growth traits of the P. elliottii families
Seen from Table 2， the family heritability of tree height， DBH and volume of P. elliottii was 0.799， 0.779 and 0.770 respectively， and their single plant heritability was 0.683， 0.829 and 0.742 respectively. It showed that the growth of tree height， DBH and volume were highly controlled by genetic effects， and efficient genetic selection of a single plant and families could be performed. Selection of superior families
Based on the above analysis， Duncan analysis of growth traits of the 13 families was carried out to select superior families with good growth traits. The 13 families were grouped using Duncans method. At the 0.05 significance level， families 9， 3， 7， 12， 15， 4 and 6 were classified as the group with the highest tree height， while families 10， 5， 14 and 1 were classified as the group with the lowest tree height， and it was lower than the average. Families 9， 12， 11， 7， 15， 4 and 6 were classified as the group with the largest DBH， while families 5， 10， 1， 2， 14 and 3 were classified as the group with the smallest DBH. The volume of families 12， 7， 15， 4 and 6 was larger than that of other families， while that of families 5， 10， 1， 14 and 2 was the smallest （Table 3， 4 and 5）. According to the growth traits of P. elliottii， families 12， 7， 15， 4 and 6 were superior families with excellent growth performances and can be used as highyield families.
Conclusions
（1）There were extremely significant differences between different families of P. elliottii in terms of tree height， DBH and volume （P<0.01）， and the families could be selected effectively.
（2）The family heritability and single plant heritability of growth traits of P. elliottii were high. The family heritability of tree height， DBH and volume of P. elliottii was 0.799， 0.779 and 0.770 respectively， and their single plant heritability was 0.683， 0.829 and 0.742 respectively. Among them， the family heritability of tree height was the highest， while the single plant heritability of DBH was the highest.
（3）According to the Duncan analysis of growth traits of the P. elliottii families， families 12， 7， 15， 4 and 6 were superior families and can be used as highyield families.
References
[1] WU JY， LONG YZ， YU GF， et al. Genetic analysis and combined selection of main economic characters of halfsib families for slash pine[J]. Scientia Silvae Sinicae， 2000， 36（z01）： 56-61. （in Chinese）.
[2] LI Y， PAN BH， HE HZ， et al. Study on selection of seedlings among halfsib families of Pinus elliottii[J]. Journal of Central South Forestry University， 2014， 34（3）： 86-89. （in Chinese）.
[3] WU JY，CHEN MG， LIU Q， et al. Seedling growth among halfsib and fullsib families of Pinus elliottii[J]. Journal of Central South Forestry University， 2016， 36（6）： 1-5， 10. （in Chinese）.
[4] WU JY， SUN JY， ZUO HS， et al. The high seed yield technology of Pinus elliottii seed orchard[J]. Hunan Forestry Science & Technology， 2011， 38（6）： 99-101. （in Chinese）.
[5] WU JY， LONG YZ， TONG FP， et al. Highyield growing techniques of seeds of Pinus elliottii firstgeneration high quality seed garden[J]. Hunan Forestry Science & Technology， 2002（4）：6-8. （in Chinese）.
[6] TONG FP， LIU ZH， WU JY， et al. Study on phosphate utilization efficiency of slash pines halfsib families[J]. Journal of Central South Forestry University， 2012， 32（12）： 154-157. （in Chinese）.
[7] WU JY， LI ZH， LONG YZ， et al. Genetic variation and selection of main economic characteristics of Slash pine fullsib family[J]. Journal of Central South Forestry University， 2010， 30（8）： 1-4. （in Chinese）.