Presentation at Subtropical Forest Research Institute, Chinese Academy of Forestry, August 19, 2010

Topics to be presented

Variation in fertility Seed orchard turnover Optimal number of clones Prediction of fertility prior to orchard establishment Deployment of clones to a seed orchard Thinning of seed orchards using the linear deployment

algorithm Biological seed production Impact of growth and seed related characters on seed

procurement

Material and Methods

Pinus sylvestris main tree species Two types of material

Seed orchard data, collected by the authors and/or extracted and analysed from published works

Models developed using real data Calculation of variance components using

ANOVA ASReml

Microsoft Excel spreadsheets used for formulation of models and Excel-tool Solver for optimizing

Mathematical framework

N

iipN

1

2

The sibling coefficient, , expresses the probability that successful gametes (sibs) will originate from the same parent compared to the case with no differences in parental fertility

N is the census number of the parents

pi is the probability that a gene in the offspringoriginates from parent i

Mathematical framework, cont’d

1)1(2

N

NCV

The relationship between sibling coefficient and coefficient of variation (CV)

≥1; if =1, all individuals have the same fertility; if =2, it means that the probability that tworandomly drawn successful gametes share thesame parent is twice that where fertilities are equal across the population

Variation in fertility

Why focus on female fertility? Seeds are the source of income from a

seed orchard Cones and seeds are used to audit the

operation About 2/3 of the tree improvement effect

comes from the seed parents as half of the pollen parents are outside the orchard

Seeds from a known tree can be harvested and counted, which can be considered as the exact number of successful female gametes of the parent

Seed orchard (cf Table 2)

Character

Variance component among clones a single year

Variance component among clones over years

Variance component of clone-year interaction (years)

Variance component among ramets within clone and year

Heritability(broad sense for individual year)

Askerud Seeds/ ramet 3813c 1.38 2318 1.23 1495 (3) 1856 0.673

Långtora Seeds/ ramet 0b 1.00 * * 4775 0.000

Lustnäset Seeds/ ramet 5830c 1.58 4751 1.48 1079 (2) 3302 0.638

RobertsforsCones/ ramet

2455 1.25 * * 2029 0.548

Skaholma Seeds/ ramet 5466 1.55 * * 1946 0.737

SävarCones/ rameta

1258 1.13 * * 2039 0.382

GnievkovoCones/ ramet

313c 1.03 149 1.01 164 (2) 976 0.243

NebraskaCones/ ramet

10271c 2.03 3242 1.32 7029 (2) 2896 0.780

ViitaselkiCones/ ramet

* 2824 1.28 * 940

VilhelminmäkiFemale strobili/ ramet

2541c 1.25 1970 1.20 571 (2) 5607 0.312

VilhelminmäkiCones/ ramet

* 2722 1.27 * 5281

Average all SOs 3550 1.35 2568 1.26 2068 2722 0.479

Average for SO with clone-year interaction

43861.437

2500 1.250 2068 2893 0.521

Seed orchard turnover

A model was developed to evaluate the benefit of various options. Options and variables included in the model are: Seed orchard size Planting density Type of orchard material (grafts, cuttings) Establishment and management costs Cone harvest and seed processing costs Development over time of the seed orchard crop Rate of genetic progress in long-term-breeding

Seed orchard turnover, cont’d

Genetic penalty, representing the gain differential between the seed orchard and a hypothetical new orchard incorporating the latest genetic progress in the breeding population

Impact of pollen contamination How the genetic quality influences the value of the

seeds The orchards productive lifespan

Seed orchard turnover, cont’d

Optimal rotation age for Pinus sylvestris orchards is suggested to be around 30 years Cone harvest starts at age 8

For Picea abies 40 years is optimal Cone harvest starts at

age 15

Optimal number of clones

Maximize a goodness criterion (“benefit”) for orchards. It’s a function of: # of tested genotypes available for selection and

planted in seed orchard The contribution of pollen from:

The ramet itself The closest neighbors The rest of the orchard and contamination

Variation among genotypes for fertility Frequency of selfing

Optimal number of clones, cont’d

Production of selfed genotypes Gene diversity (=status number) Influence of contamination Genetic variation among candidates Correlation between selection criterion (e.g. height

in progeny test) and value for forestry (e.g. production in forests from the orchard)

# of clones harvested

Optimal number of clones, cont’d

Optimum # of clones in Pinus sylvestris is suggested to be 16, assuming ψ=2

If ψ=1.24 as mentioned before, then optimum # is 11

Prediction of fertility prior to orchard establishment

Fertility varies over years Cumulative cone-yield data would

provide greater reliability Correlations between female fertility

in clone archives and performance of the same clones in seed orchards was close to zero

Thus it’s not worthwhile to collect data as a selection criterion when designing new seed orchards

Deployment of clones to a seed orchard

“Linear deployment” means that clones are deployed proportional to their breeding values

A higher proportion of pollen from a clone constitutes a higher probability of self-fertilization, but seldom leads to fertile seed

Outcrossing pollen is more efficient than pollen that is delivered to ramets of the same clone

Deployment of clones to a seed orchard, cont’d

“Outcrossing effective number” is coined to describe the balance between # of ramets and the effective # of the realised seed crop

Comparison between optimal and linear deployment of clones, under same outcrossing effective number, produced similar results.

At low effective numbers, impact of selfing will be greater

Deployment of clones to a seed orchard, cont’d

Deployment of clones to a seed orchard, cont’d

Pinus sylvestris seed orchards are suggested to be established with 20-25 tested clones, linearly deployed according to their breeding values, with an effective number of 15-18 clones based on number of ramets planted

Thinning of s.o. using the linear deployment algorithm

Thinning by linear deployment results simultaneously in greater genetic gain, higher effective clone #, lower thinning intensity

Gives more flexibility for future thinning, mass production of controlled crosses, selective harvest etc

Thinning of s.o. using the linear deployment algorithm

ParameterBefore thinning

Max. Ne Max. gain at given Ne Truncation selection1

After thinning

Clones 32 32 32 31 29 26 24.35 32

Ramets 5351 3644 3644 3644 3644 3644 3644 3644

Gain 105.96 106.89 108.18 108.52 108.76 108.92 108.97 108.52

Ne 19.99 26.8 24 22 20 18 16.82 22.00

g0 - -667.71 94.86 97.84 100.37 101.15 101.82

b 0 0.20102 16.17 24.87 49.05 79.89

Biological seed production

Seed orchards are often located on abandoned farm land, with favorable climate and soil conditions, which normally increases the seed production

120-150 seeds/m2 or 10 kg/hectare would be possible Seed orchards are generally young compared to seed

stands, and thus seed production potential is underestimated

The studied seed orchards indicate a average biological seed production of 9 kg/hectare

Impact of growth and seed related characters on seed procurement

Growth, morphology and number of strobili have limited genetic variation, thus should not be considered when selecting clones for orchards = take care of it with cultural management

Seed-related characters have impact on seed procurement

Around ¼ of cones are situated in the top level of the crown, ½ in the middle and ¼ in bottom level

Impact of growth and seed related characters on seed procurement, cont’d

Cost for harvesting cones is dependent on tree height, thus pruning is recommended

Variation in fresh weight of cones – related to ripening- can have impact on seed procurement

Summary

When establishing a new seed orchard, little emphasis should be put on selecting clones with high fertility

A seed orchard with tested clones should contain 20-25 clones, linearly deployed, resulting in an effective number of 15-18 clones

Harvest of cones can often be started as soon as the first cones are available, but contaminating pollen can change the adaptability of the seed

For Pinus sylvestris, the optimal active life time of seed orchards seems to be 30 years, for Picea abies 40 years

Highs costs of cone harvest can be reduced by pruning the seed orchard trees

Thank you for your attention