Analysis of the parental reproductive balance in a Pinus pinaster Ait. seed orchard

E. Merlo, J. Fernández-López


The number of female and male strobili were assessed for 22 clones in a Pinus pinaster Ait. seed orchard along four consecutive years. The data showed that differences for the production of both female and male strobili among clones were very large and statistically significant for all years examined. Differences in female strobili production among clones were more variable than in male strobili. Pearson’ s correlations between years were highly significant. Both correlations between female and male flowers were moderate and positive for all 4 years. Broad-sense heritabilities for flower production on an individual ramet basis varied from 0.14 to 0.50, while those on a clone-mean basis were much higher, from 0.39 to 0.82. Maleness index indicated high sexual symmetry (Mi= 0.47-0.49). The results are useful for planning further activities in the seed orchard such as pruning, roguing or selective cone harvest.


strobilus production; sexual symmetry; clonal variation; genetic diversity