Conifer Reproductive Biology 2007Conifer Reproductive Biology 2007

OverviewOverview

Apical MeristemsReproductive CyclesSeed DevelopmentSeed DevelopmentCollection Due DiligenceCollection Due DiligencePostPost--collection Handlingcollection HandlingPLIPLI

It all starts in the ApicesIt all starts in the ApicesApical meristems found in shoot-tips; buds, roots, under bark, within Pine needle fasciclesMeristems are the site of cell division – producing tissues “in their wake”Primordia for next years structures from apex are ‘differentiating’ within developing budsPosition, shoot vigour, tree vigour, climate will impact primordia fate

Apical meristemproducing primordia

Different structures having different timing

Pine long-shoot bud

Three BC conifer Reproductive CyclesThree BC conifer Reproductive Cycles

Yc sometimes matures without a 2nd dormant period

Pine fertilization time one year after pollination

LodgepoleLodgepole Pine Reproductive CyclePine Reproductive Cycle

Ovule and Ovule and MegagametophyteMegagametophyte DevelopmentDevelopment

PolyembryonySeveral embryos can develop within one ovule, competition is high usually only one fully develops

Simple – more than one egg fertlizedin an ovule (genetically different)

Cleavage – identical proembryos form (genetically identical)

FertilizationPro-embryo stage

Mid-Embryo Stage

Immature and Mature EmbryoImmature and Mature Embryo

Embryos have fairly primitive vascular systems (primary xylem and phloem)

When can When can FalldownsFalldowns occuroccurEnvironmental

Spring frost – hardiness veg > > Excess moisture – delayed pollination

PhysicalPollen viability – pollen may not germinatePrefertilization incompatibility – no germination, no tube growth, incomplete tube growthPostfertilization inviability – incompatibility / selfingCone abortion – if insufficient pollination occurs

PestsMost Species will form seeds even if no Most Species will form seeds even if no

pollination occurspollination occurs

Reproductive Potential (RP) = # cones/tree * seeds per coneReproductive Success (RS) = subset of above making it to maturity

Seed Potential (SP) = fertile scales X 2 {Fertile scales Pw=80%/ Pli = 33%}Pollination Success (PS) = amount of pollen reaching the ovules

Seed Efficiency (SE) = seeds obtained divided by seed potential

7039

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0%

20%

40%

60%

80%

100%

Hw Fdc Cw

Seed Ef f iciency

Embryo abort ion

Ot her Pref ert ilizat ion

Pollen inviabilit y

Ovule abort ion

No Pollen

PrePre--Collection EvaluationCollection EvaluationMonitoring of the condition of cones and seeds prior to harvest is important to:

determine crop or ‘desired’ cropSeed planning (orchard timelines / present + future needs)Plan resource requirements (pick, interim storage, transport)

determine maturity levelMore frequent monitoring closer to collectionProper sampling of stand/orchard variability

determine pest problemsPro-active or active control in orchardsEarly detection of fungal problems can often be remedied

Seed quality (Germination and storability) is maximal at time ofnatural dispersalDehydration of cones and seeds accompanies maturationMoisture content is related to damage potential (m.c. then risk )

Due DiligenceDue DiligenceUse new sacks or properly sterilized sacks (steam/hot water)Fill sacks ½ to ⅓ full to minimize heat build-upKeep sacks off ground / on sides to reduce weightPlace sacks in shady environment with good air circulationTurn sacks to maintain uniform aeration

Frequency depends on moisture contentMove sacks daily from collection site to interim storageLimit amount of debris (mc / fungi / abrasive)

Squirrel cachesCan produce good quality collections – cheaplyRISK – especially in wet, cool weatherHandle with extra care (maturity, heat build-up??)

Cone and Seed EvaluationCone and Seed Evaluation

Cone, seed coat, wing colourDegree of cone flexingEase of seed wing releaseAssess insect/fungal activity Estimate seed yield (per cone)

Dissecting cones - time consumingpredictions based on correlations with half-cone counts are commonPli – whole cone assesments

Seed - embryo and megagametophyte condition (cutting tests)

Cutting TestsCutting Tests‘seed anatomy tests’to provide information on characteristics of seed in a sampleclassify to needs% viable% immature% empty% damaged and discoloured% rotten% resin filledClassification examples

Seed ImmaturitySeed ImmaturityA basic measure of maturity is the embryo length relative to the corrosion cavity (i.e. 33%)This is not the only maturity criteria

cone/seedwing separationmegagametophyte textureovernight shrinkage

Below a certain point (?50-60%?) seed will not germinateSeed ‘vigour’ reducedProcessing / Upgrading problematic

PostPost--Collection HandlingCollection Handling“Field” MC ⇑, Risk ⇑‘generally’ 4-6 weeks interim storage recommendedHw and Cw ship immediately!

Goal is to slowly dry the cones (after-ripening)turn sacks (uniformity)Protect from sun, rain, animalsAllow for good air-flow (1 sack depth*)

*Serotinous Pli sacks can be stacked

Cone Maturation in DouglasCone Maturation in Douglas--firfir

Low dormancy in Low dormancy in CwCw !!!!!!

Recommended that Cw and Hw shipped directly to seed processing facility

Seed Wing ReleaseSeed Wing Release

Immature & Aborted SeedsImmature & Aborted Seeds

PestsPests along the Wayalong the Way

Seed from Dead TreesSeed from Dead TreesLots of evidence in literature that seed remains viable in serotinouscones for “decades” – no vascular connection CANOPY SEED BANKS

2004 – 9 small collections from Nadina Forest District from trees known to be dead between 7-10 years (Thank you Carolyn Stevens)

Very small quantities and we did not process the seed, but wegerminated unprocessed seedPerformed cut tests on ungerminated seeds to estimate seeds removable during processingAllowed for an estimation of potential germination

The potential germination ranged from 70 to 87%

Possible, but there may be reductions in yield and Germination, especially if cone serotiny is compromised

PliPli Cone ClassesCone ClassesClass 1 Class 2

Class 3 Class 4

Cone Class 2Cone Class 2Towards branch Away from branch

Cone Class 3Cone Class 3Towards branch Away from branch

Pli Cone ClassesClass 1 Class 2

Class 3

Class 4

Illustrating cone aspect variationprotection from wearing against stem

PliPli Cones To AvoidCones To AvoidOpened cones

Insect damaged cones

Very small cones(2 - 2.5 cm)one normal cone for reference

Resin covered conesrocks

Breaking of Breaking of serotinousserotinous resin resin

bondbond

Opening variation –which still have seeds

Tree Type Cone Class

Un-attacked

Green-attack Red-attack Dead

1 You are Lucky

Generally OK - Concern of MPB attack during seed development (esp. with early and/or multiple attacks/yr)

Probably OK, potential for MPB impact on past crop development

Probably not a common situation?

2 You are Lucky

OK Probably OK, potential for MPB impact on past crop development

OK

3 Evaluate to decide whether to include, exclude, or process separately

Evaluate to decide whether to include, exclude, or process separately

Evaluate to decide whether to include, exclude, or process separately

Evaluate to decide whether to include, exclude, or process separately

4 DO NOT COLLECT FROM

Best Guess at Reality