How seed orchard culture affects seed quality: Experience with the southern pines

Tree improvement programs have influenced significantly the quality of southern pine seeds produced when compared to collections from native stands. Seed orchard management practices such as fertilization can increase seed size and reduce seed dormancy. These result in the need for less complex pregermination treatments. Repeated cone collections from the same clones facilitate collections according to ripening (cone specific gravity), which can improve seed germination and storage. However, cultural practices may result in seed properties that are more sensitive to damage during processing procedures and result in lower quality unless special care is provided during this stage of handling. The effect of orchard management practices on seed quality also varies by species, with loblolly pine being less affected than longleaf pine. Les programmes d'amelioration genetique ont eu une influence simificative sur la aualite des semences de ins du sud lorsau'on lei compare aux skmences recueirlies dins Ies peuplen;ents naturels. Les pratiques d'amenagement des vergers a graines telle la fertilisation peuvent accroitre les dimensions de la graine et reduire la dorrnance. En consequence, i l est moins necessaire de recourir a des traitements complexes de pre-germination. Les cueillettes repetees des cBnes sur les m&mes clones facilitent les recoltes de graines pour ce qui est de la maturite (poids specifique des cbnes), ce qui peut amkliorer la germination et I'entreposage. Toutefois, les pratiques de production peuvent modifier les proprietes des semences en les rendant plus susceptibles d7&tre endommager lors de la manipulation et entrainer une baisse de la qualite a moins qu'une attention speciale n'y soit accordee au cours de la manivulation. L'effet des vratiaues d'amenagement . . des vergers sur la qualite des semences varie selon I'espece