Báo cáo nghiên cứu nông nghiệp " Seed-Producing Stands "

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There are many methods to obtain seed for planting •Meeting immediate needs –Seed from individually good phenotypes –Seed from seed stands/seed production areas •Meeting long-term needs –Seed from seed orchards •These seed sources are different in genetic quality

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Nội dung Text: Báo cáo nghiên cứu nông nghiệp " Seed-Producing Stands "

Seed-Producing Stands
There are many methods to obtain seed for planting • Meeting immediate needs – Seed from individually good phenotypes – Seed from seed stands/seed production areas • Meeting long-term needs – Seed from seed orchards • These seed sources are different in genetic quality
Why not just collect seed out of plantations? • We may not know the genetic origin of the plantation – it could be inferior, or the genetic base too narrow. • There has been no selective thinning to remove inferior trees in the plantation. • The inferior trees contribute their pollen to the other, better trees in the plantation, lowering seed quality.
Why not just collect seed out of plantations? • Because the trees are growing at close spacing, flowering may be poor, resulting in inbreeding and poor genetic quality of seed. • Much better to get our seed from well-managed seed-producing stands.
Collect seed from superior trees only when seed is needed for immediate planting Inferior trees contribute pollen to better trees
Types of seed producing-stands • Seed stand • Seed production area • Seed orchard – Seedling seed orchard – Clonal seed orchard
Seed Stand An area of planted or natural forest of superior appearance (phenotype) but unknown genetic potential Teak seed stand, Thailand
Seed Stand A mature plantation of Eucalyptus regnans. We may not know the original seed source.
Seed Production Area • Plantation raised from suitable provenance, selectively thinned and managed for seed production • At least 20 unrelated families to minimise inbreeding • Family identity of individual trees not known • Heavy selective thinning removes inferior trees, retaining good trees to produce seed • Produce seed of somewhat improved quality E. camaldulensis SPA, Laos
Seedling Seed Orchard • Developed by selective thinning a progeny trial which tests many (>100) different families of a species • Progeny trial reveals which families and trees are growing best • Inferior trees are removed in 2-3 thinnings • All trees of some inferior families may be completely removed • Family identity of every tree is known • Seed from the best trees of the best families have the best genetic quality – producing best plantation A. crassicarpa SSO, Thailand
Clonal Seed Orchards • Consists of many ramets from each of 15 or more superior clones • The ortet of each clone is carefully selected from field trials • The ramets are propagated by grafting or by cutting propagation • Use wide spacing to encourage crown development and flowering • Density 100 -150 trees per ha, depending on the species • Clonal identity of every tree in the orchard is maintained • Clones which produce poor- performing seeds may be removed from the orchard Teak clonal seed orchard
Layout of a grafted clonal seed orchard Eucalyptus maculata, Australia Wide spacing Adjacent trees are from different clones Excellent weed control