TAILIEUCHUNG - Báo cáo khoa học: "Estimation of genetic parameters in eastern cottonwood (Populus deltoïdes Consequence for the breeding strategy"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Estimation of genetic parameters in eastern cottonwood (Populus deltoïdes Consequence for the breeding strategy. | 307 Ann. Sci. For 1989 46 307-324 Elsevier INRA Original article Estimation of genetic parameters in eastern cottonwood Populus deltoides Bartr. . Consequence for the breeding strategy c. Pichot and E. Teissier du Cros INRA station d amélioration des arbres forestiers Ardon 45160 Olivet France received 21 August 1987 accepted 17 April 1989 Summary Poplars bred for the future by INRA include two North American species eastern and black cottonwood and the European black poplar. The breeding strategy now under discussion needs to be based on the biological and genetic properties of the species. The present study aims to estimate the genetic parameters in the eastern cottonwood Populus deltoides Bartr. . A factorial crossing design involving 6 females and 6 males was carried out between 1971 and 1980. Observations on copies 0f the parents and of their offsprings were made in 1985 and 1986 in a design laid out in the INRA experimental nursery near Orleans France. Observations concerned phenology growth and wood quality. Firstly the results showed a significant variability of most traits whether among parents among families or among cloned full-sibs but this variability was greater among parents than among families which can be explained by the assumption that allelic fixation occurred in the natural stands the parents originated from. This allelic fixation was high for phenologic traits moderate for growth traits and absent for wood quality traits. Secondly heritabilities were estimated. Broad sense heritabilities were generally high and significant for all types of traits. Narrow sense heritabilities estimated from parent-offspring regression are extremely low for wood quality traits. Thirdly additive genetic correlations between traits were estimated. Significant values were found between phenology and growth traits and between growth termination and wood basic density which means that fast growing genotypes should be looked for among early starters rather than among

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