Testing the performance of acacia hybrid clones in different regions of Vietnam Ha Huy Thinh 1, Nguyen Dinh Hai 1, Le Dinh Kha 1, Nguyen Duc Kien 1 Brian Baltunis 2, and Chris Harwood 2 1 Research Centre for Forest Tree Improvement, Forest Science Institute of Vietnam 2 CSIRO Sustainable Agriculture Flagship

Strong scientific leadership by Prof. Le Dinh Kha, Dr Ha Huy Thinh and colleagues at Forest Science Institute of Vietnam Work commenced 1991 Government regulations approved tested clones for use in plantations Training/extension packages provided to regions (e.g. – no F 2 ) >200,000 ha plantations by 2009, tremendous economic benefits History of acacia hybrid development in Vietnam

Select 30 outstanding F 1 hybrid ortets in 3-year-old A. mangium plantations Fell candidates, propagate from coppice shoots, plant hedge gardens First clone trials screening 20 clones 1996 Proving trials of best clones and controls ☑ Study wood properties of felled trees 1998 Nurseries for clonal propagation Operational planting of best clones Development of new series of hybrid clones Over 200,000 hectares of plantations established (about 10 production clones) Tissue-culture to maintain juvenility xx

Low-cost propagation systems for acacia hybrid, Vietnam Local materials Labour intensive High output: up to 2M plants / year Low production cost: US 2 cents per ramet Hedge plant orchard –ex tissue culture

Testing new acacia hybrid clones Origin of new candidate clones? –Intensive selection of natural hybrids in plantations –(Controlled pollination) Pre-screening of hybrid trees before cloning and clonal testing – an important step –5 new candidate clones were chosen for testing from 100 hybrid individuals in plantations at Ba Vi Standard clone testing protocols of RCFTI –Initial clone trials: 3 reps of 10-tree line plots at two or more locations Here, we report clonal testing of 21 pre-screened hybrid clones against the original set of 6 production clones and pure- species controls, in four trials

Different users – different requirements! Export woodchips: volume and density (sell by dry weight) Sawmill: volume, straight logs, knot free, low shrinkage… Vietnamese pulpmill: volume, density and pulp yield Grower: sells by standing volume

What do we want to improve?

Objective traits and corresponding selection traits Objective trait (harvest age, 6-12 years)Selection traits (age 3-4 years) Stand volume at harvestDbh, height, health, survival % of volume that is sawlogStem straightness, light branching (affected by stocking & silviculture) Log straightnessStem straightness Log basic densityPilodyn, wood core basic density Wood hardness and stiffnessAcoustic wave velocity, basic density % heartwood% heartwood? Low & uniform wood shrinkageShrinkage properties of wood samples Pulp yield (% dry weight)NIR-predicted pulp yield Absence of knot-related defects(determined by silviculture)

Ba Vi Nghe An Quang Binh Dong Nai 20 0 N 12 0 N 16 0 N E E Trial locations

Trial details

Allocation of treatments to 4 clonal trials production clones from year 2000 other hybrid clones pure-species controls * tested in trial

Line plot at Ba Vi trial, age 9 years Nghe An trial age 8 years

Dong Nai clone trial at age 3.5 years 49-tree square plot of clone BV10 Fast-growing: standing volume over bark at 35 months averaged 56 m 3 /ha Average MAI at 3 years = 19 m 3 /ha

Assessing wood basic density Measuring Pilodyn penetration at Ba Vi Collecting wood disks at Nghe An for basic density measurement

Statistical analysis Simple model to test significance of treatment differences: replicates and treatments as fixed effects Calculated Pearson correlation coefficients r for clone means to examine trait-trait correlations Pure-species controls excluded from data sets for significance testing and when calculating correlations Mixed model (replicates fixed, treatments random) used to estimate clonal mean repeatabilities

Survival good (80+%) except at Quang Binh (48% at 2 years) Growth was faster at Dong Nai in the south of Vietnam Hybrid clones grew significantly faster than Acacia mangium and A. auriculiformis in the north, but no faster than A. mangium at Dong Nai n.s. Overall growth performance

Did hybrid clones differ from one another? (pure species controls excluded)

Clonal mean repeatabilities were high for growth traits except at Dong Nai, and high for pilodyn (pure-species controls excluded)

4-year Dbh rankings at Ba Vi and Nghe An not very consistent (r = 0.33), but some clones grew well at both sites auriculiformis mangium BV10 BV75 BV33 BV73 Critical diffs. P=0.05

Pilodyn was a fairly good predictor of wood disk basic density at Nghe An (year 8) Clone density - breast height disks from 3 ramets per clone Clone pilodyn - 2 shots per ramet from 15 ramets per clone BV16 c.d (P=0.05)

No clear relationship between clone basic density and dbh at Nghe An (age 8 years) auriculiformis mangium BV16 c.d (P=0.05)

Dbh (age 4) and pilodyn (age 8) not well-correlated at Nghe An r = 0.09 for hybrid clones auriculiformis mangium BV16 c.d. (P=0.05)

Pilodyn rankings at Ba Vi and Nghe Anh consistent (r = 0.71 for hybrid clones) BV16 mangium auriculiformis CQ58 Critical difference (P=0.05)

Conclusions The performance of the new candidate clones was generally good – pre-screening had worked well Hybrid clones outgrew A. mangium in north and central Vietnam but not the south A. auriculiformis much slower than hybrid and mangium Significant differences among hybrid clones for growth except at the Dong Nai trial site in the south of Vietnam Significant differences among clones for wood density at the two sites where density/pilodyn was assessed

Conclusions (cont.) No clear relationship between growth and basic density amongst the different hybrid clones Clone x Environment interaction was apparent for growth Little Clone x Environment interaction for wood density Tests using 3 replicates of 10-tree line plots worked well for first-stage screening of clones Large-plot tests (e.g. 49-tree plots) to evaluate clone performance at the stand level should use 5, not 3 replicates

The future Some “new series” clones (e.g. BV71, 73, 75 and TB11) have been approved as production clones by Vietnam’s Ministry for Agriculture and Rural Development Different clones will be favoured by different user groups based on their rankings for different objective traits and regional differences in performance Need further hybrid breeding and selection to broaden the genetic base of acacia hybrid plantations

The future Need further hybrid breeding and selection to broaden the genetic base of acacia hybrid plantations With broad and well-studied breeding populations of A. mangium and A. auriculiformis and a well-tested set of outstanding existing acacia hybrid clones, Vietnam is well- positioned to exploit advances in genetics and genomics New ACIAR project

Expanded screening of candidate hybrid genotypes Field trial of family-identified F 1 hybrid seedlings identified in the nursery from open-pollinated A. mangium families

Acacia auriculiformis: potential for genetic selection in hybrid breeding Hai et al. Journal of Tropical Forest Science 20(4): 313–327

Acacia auriculiformis: genetic variation in wood quality Dr Phi Hong Hai – his research shows strong genetic differences in wood density, shrinkage and stiffness among auriculiformis families and clones

Acknowledgements My co-authors!!! Support from ACIAR Project FST 2008/007 “Advanced breeding and deployment methods for tropical acacias”, Forest Science Institute of Vietnam, and CSIRO. Contributions from FSIV staff, especially Mr Do Huu Son