Báo cáo khoa học: Tree improvement programs for European goals and strategies

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Báo cáo khoa học: "Tree improvement programs for European goals and strategies" Review article oaks: Tree improvement programs for European goals and strategies PS Savill, PJ Kanowski Oxford Forestry Institute, Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK Most work concerned with the improvement of European oaks is concentrated onSummary —Quercus robur and Q petraea. Improvement is constrained by limited knowledge of the extent andpattern of genetic variation, the long period to reproductive maturity, levels of seed production rela-tive to demand and difficulties in vegetative multiplication. The goals of improvement activities havefocused on straightness, vigor and desirable branching; on wood anatomy, shrinkage, density andcolor, and susceptibility to problems such as frost cracks, shakes and defoliation. Three aspects ofbreeding are currently receiving attention: 1) in vitro methods for regeneration, flower induction andgenetic manipulation; 2) technologies for clonal multiplication, and 3) elements of classical breedingprograms. Recent conceptual and technological advances and greatly increased research activityhave raised expectations of genetic progress, which will need to be accompanied by developmentsin associated topics such as silviculture, pathology and wood science.oak / Quercus / breeding / genetic conservation / improvementRésumé — Programmes d’amélioration des chênes La européens : objectifs et stratégies. plu-part des travaux concernant l’amélioration des chênes européens est concentrée sur Quercus roburet Q petraea. L’amélioration est rendue difficile du fait de la connaissance limitée des variations gé- de la longue période pour atteindre la maturité reproductive, de la quantité de graines pro-nétiques,duites par rapport à la demande et des problèmes rencontrés concernant la multiplication végéta-tive. Les buts de l’amélioration ont été concentrés sur la rectitude, la vigueur et la ramification ainsique l’anatomie du bois, le retrait, la densité, la couleur et la sensibilité à des problèmes tels que lesgélivures, les fissures et la défoliation. Trois aspects de l’amélioration génétique sont actuellementabordés : 1) les méthodes de régénération in vitro, d’induction florale et de manipulations généti-ques; 2) les techniques de multiplication clonale; et 3) les éléments de programmes d’améliorationclassique. De récentes avancées technologiques et conceptuelles ainsi qu’une activité accrue de larecherche, ont apporté de nouveaux espoirs d’amélioration génétique qui devront s’accompagner deprogrès en sylviculture, pathologie et science du bois. reproduction / conservation génétique / améliorationchêne / Quercus / establishment of only between 2 and 7.5INTRODUCTION ha/year of plantations at the typical Ger- man stocking of 10 000 trees/ha (Kleinsch-Of the 27 European species of oak, only 3 mit, 1986).are of major economic significance: Quer-cus petraea, Q robur and Q suber. Thefirst 2 are important components of the for- Goals: breeding objectivesests of Europe north of the Mediterranean and selection criteriaregion, and their timber is highly valued.We concentrate on them in this paper. Thethird species, Q suber, produces most of Breeding objectives describe the goals ofthe world’s commercial cork and is the ba- genetic improvement and selection criteriasis of an important industry, especially in as the traits by which this improvement will be realized (Cotterill and Dean, 1990). InPortugal. theory, breeding goals include all traits of Despite their economic importance, a economic importance; selection criteriacomprehensive set of constraints the — usually comprise a more restricted set,long rotations, the delay in the onset of chosen for their genetic control and rela-flowering, uncertainty as to the timing of tionship with the breeding objective. Typi-heavy fruiting (good seed years occur at cally traits which influence size and quality2-10-yr intervals in most regions), impossi- at harvest are included as breeding objec-bility of storing seed for extended periods, tives and weighted according to their rela-and difficulties in vegetative propagation tive economic importance. Selection crite- have made oaks relatively difficult sub-— ria are likely to include those juvenilejects for geneticists and tree breeders, par- ...