Báo cáo nghiên cứu nông nghiệp " Development and Management of Seed Production Areas "

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Why not just collect seed out of plantations?

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Nội dung Text: Báo cáo nghiên cứu nông nghiệp " Development and Management of Seed Production Areas "

Development and Management of Seed Production Areas Khongsak Pinyopusarerk CSIRO/Ensis-Genetics Canberra, Australia
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 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 Because the trees are growing at close spacing, flowering may be poor, resulting in inbreeding and poor genetic quality of seed
Seed Production Area Seed production area is a stand developed and managed specifically for seed production purpose. Two ways to develop seed production area: – Develop from existing planted stand – Develop from specially planted new stand
Existing stand suitable for conversion to seed production area Known seed origin Trees are mature but not too old Near full stocking and good phenotypes No pests or diseases Proven capacity to flower and set seed Easily accessible Not subject to commercial harvesting in near future Conversion to seed production area by selective thinning
Stand not suitable for conversion to seed production area Very poor plantations with evidence of disease attack
Development of seed production area from specially planted stand Site should be representative of target planting areas Evidence of flowering and seed set at the location Seed from most suitable provenance or several provenances Start like a new plantation Initially close spacing (more trees for selective thinning) – 3m x 2m for most eucalypts – 3m x 3m or 4m x 2m for acacias Fertilizer application to help in successful establishment
Establishing new seed production area 8/1996 2/2002 A seed production area of E. camaldulensis in Laos, 5 ha Initial spacing 4m x 2m (1250 stems/ha) Two selective thinnings reduce to 300 stems/ha
Size of seed production area 4-5 ha is appropriate for most species May be smaller (< 1 ha) for heavy seed producer, e.g. eucalypts Area should be close to square, not long narrow block to promote more cross pollination Isolation is important to minimise contamination from outside pollen !!!
Selection of trees in seed production area Development of SPA involves 2-3 thinnings to remove undesired trees, retaining good trees to produce seed Retained trees should have the following characteristics – Fast growth – Straight single stem – Good crown development – Good self pruning – Free from insects and diseases No trees below standard should be kept, regardless of the gap For dioecious species (e.g. casuarinas), make sure to have enough male trees (at least 30%) for pollination
Thinning seed production area An essential activity to remove poor-performing trees Aim to reduce stocking to 150-200 trees/ha At least 2-3 thinnings each time selectively removes 50% of trees Thinning in small groups, e.g. 16 (4 x 4) trees, for ease of comparison Avoid thinning in typhoon season, strong winds can cause wind-throw and crown damage Avoid damage to adjacent trees
A mature plantation old enough for conversion to seed production area 1250 stems/ha
Seed production area before first thinning Thin in groups: remove poorest 8 out of every 16 trees Selection criteria: - growth - stem straightness - light branching Initial stocking: 1250 trees/ha
Seed production area - after first selective thinning Stocking: before : 1250 trees/ha after: 600 trees/ha
Seed production area – after second selective thinning Two selective thinnings each removing 50% of trees Stocking: Initial : 1250 stems/ha After 1st thin : 600 After 2nd thin: 300 Collect seed from remaining, superior, trees after mass flowering following thinning
Seed production area – after third selective thinning Three selective thinnings each removing 50% of trees Stocking: Initial : 1250 stems/ha After 1st thin : 600 After 2nd thin 300 After 3rd thin 150 Collect seed from remaining, superior, trees after mass flowering following thinning
A seed production area after three thinnings 150 trees/ha
A specially planted seed production area, before first selective thinning at 2 years old h h hh hh Row 1 h h Seedlot used hh hh to establish Row 2 h SPA: mix of h hh hh equal weights of 50+ Row 3 hh hh unrelated, hh superior seed Row 4 families h h hh hh h Row 5 h Initial spacing h h hh 3mx3m (1110 stems/ha Row 6
Selection before first thinning age 2 years Thin in groups: Row 1 – remove poorest 8 out Row 2 of every 16 trees Row 3 Selection criteria: - growth Row 4 - stem straightness - light branching - (wood quality?) Row 5 Initial stocking: Row 6 1110 trees/ha
After first selective thinning Row 1 Row 2 Stocking: Row 3 Initial : 1100 trees/ha After 1st thin : 550 Row 4 Row 5 Row 6
After second selective thinning, age 4 years Two selective Row 1 thinnings each removing 50% of Row 2 trees Stocking: Row 3 Initial : 1100 stems/ha Row 4 After 1st thin : 550 After 2nd thin 275 Row 5 Collect seed from remaining, superior, trees after mass flowering following thinning