Analysis at the Juvenile Stage of a Multilocate clonal test of Norway spruce (Picea abies (L.) Karst.). Genetic Variability

1989

S. 15-29

5 Abb., 8 Tab., 20 Lit. Ang., Fr, Zfsg. En, Fr

Unselbständiges Werk

200014635

A study of height increment and flushing was performed with 1 130 clones of Picea abies after 5 years in the field. These clones were the result of a selection in nursery at age 4, from polish provenances and progenies. Material was distributed in 3 localities. For total height, the clonal mean was greater than reference provenances. Clonal heritability showed a decline during the first year after planting. After adjustment to block effect, the cumulated variance for provenance, progeny and clone levels, termed genetic variance, represented 17-28% of the total variance. For annual shoot increment, the same feature was observed with absolute values. Nevertheless, evolution of clonal heritability differed, and seemed to increase after the second year. Cumulated shoot increment from planting to the 5th year was 20 cm higher for clones than for reference provenances. Heritabilities were 0.32, 0.56 and 0.63 respectively for the 3 localities, and genetic variance represented 13-22% of the total variance. Flushing, studied on sites 2 and 3 during the spring of 1986, exhibited a clonal heritability between 0.79- 0.89, and a genetic variance proportion varing from 52-57%. Genetic correlations at clone level between height and flushing were -0.12 (site 2, 758 clones) and +0.28 (site 3, 1 040 clones); this change may have been caused by a difference in genetic composition from one site to another. Correlations of clonal means on 2 sites were significant. After adjustment to site effect, clones were better than references for height (+19 to 29%) and flushing (8 days). Overall clonal heritabilities were high : 0.86 on flushing, 0.81 on total height and 0.62 on cumulated shoot increment in plantation. In conclusion, three main points are discussed. (i) The reduction with time of the total height clonal heritability may reflect nursery effect, or express changes in genetic regulation of growth from nursery to plantation site. (ii) The preliminary selection steps in forest and in nursery which led to the selection of these clones did not erase the high natural variability due to provenace and progeny-within-provenace levels. (iii) For the following selection steps, results point to the cumulated shoot increment in plantation as the best criterion for vigor description. Finally, the clonal population studied seems to be suitable for further selection, and may ultimately provide a performant multiclonal variety.