Báo cáo Nghiên cứu khoa học Genetic Improvement of Forest Trees

Genetic Improvement of Forest Trees Khongsak Pinyopusarerk CSIRO/Ensis-Genetics Canberra, Australia Why Do We Need Tree Improvement? To develop new plantations superior to their predecessors in one or several key economic traits. Variation within a Species Offer potential for improvement through selection and breeding between provenances between families Basic Elements of Tree Improvement • Well defined strategy and plan • Clear objectives • Hierarchy of populations • Selection and mating • Personnel and funding Well Defined Strategy and Plan • Improvement strategy – the framework of ideas. Essential elements are: (a) Type of selection and mating, starting with a broad genetic base (b) An efficient system for mass propagation of outstanding selected individuals either as seed or cuttings • Improvement plan – a detailed work plan to implement the chosen strategy Clear objectives Which traits to be improved? Disease resistance Stem form Vigour Choosing traits for measurement and assessment • survival• dbh • height • stem volume • wood density, colour • timber strength, stiffness • timber defects • pulp yield • fibre length • stem straightness • axis persistence/forking • branch thickness • branch angle • pest and disease resistance • growth stress • tension wood • fodder production • fodder value • other traits? ? ?? ?? Activity Cycle – Hierarchy of Four Populations Base population Breeding population Propagation population Production population BASE progeny tests seed orchards/ clone banks plantationsselection mass propagation select trees mating Propagation Population (seed orchards) Selection Breeding Population Base Population Activity cycle for tree breeding Crossing Planting stock for plantations Selection and Mating • Key activities in breeding • Progeny trials to assess variation within a species • Open pollination or controlled pollination • Minimising potential of inbreeding Conditions for Production of Inbred Seed Pollen Self-fertilization Isolated tree Impact of Inbreeding Conditions for production of high-quality seed Pollinators Outcrossing • Wide genetic base - most trees unrelated • Good cross-pollination • Outcrossing between unrelated trees Controlled Pollination Improvement Program of Acacia auriculiformis Good progress in Thailand and Vietnam Hybrids • Natural or artificial • Heterosis in F1 generation Hybrids Uniformity of F1 generation Segregation of F2 and subsequent generations Seed Production Area Î Low-cost technology • Establish stands with a mix of 50- 100 unrelated seed parents from many sources • Start at close spacing to allow heavy and early selective thinning • Produce seed of somewhat improved quality • Outstanding individuals may be used for clonal forestry after field testing Concluding Remarks • Tree improvement is long-term investment and must be well planned and executed • Tree improvement must be on-going with subsequent breeding cycles • Need to improve skills of staff • Abundant production of very high quality seed is key component of tree improvement