Pankaj K. AGGARWAL

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Pankaj K. AGGARWAL. IUFRO Division 5 Conference 5.01.01 Biological control of wood quality. Variation in growth strains in five clones of Eucalyptus tereticornis. Pankaj K. Aggarwal and Shakti S. Chauhan. - PowerPoint PPT Presentation

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  • Pankaj K. AGGARWALIUFRO Division 5 Conference5.01.01 Biological control of wood quality

  • Pankaj K. Aggarwal and Shakti S. ChauhanInstitute of Wood Science & Technology (Indian Council of Forestry Research & Education)Bangalore, India Variation in growth strains in five clones of Eucalyptus tereticornis

  • India has 2.5% of the geographical area and 1.5% of the world forest area and support 16% population of the world. Gap between demand and supply of timber is widening and therefore shortage of conventional preferred species, high cost, lengthy production period of Conventional species has necessitated the need to utilize man made forests which is available. Conventional technology for Processing is not appropriate for fast grown species as they are inherently characterized by growth stresses due to which they are prone to have processing problems. Also wood is juvenile and liable to cause distortions during sawing and seasoning. Background

  • What are growth stresses ?Growth stresses are generated in the cambial layers of woody stems during the cell maturation.

    Growth stresses are generally resolved in the longitudinal, radial and tangential directions following the natural geometry of the trees.

    These are common to all species however their magnitudes differ from species to species.

    Contd

  • In general, these stresses are reported to be less in softwood as compared to hardwood.

    Most emphasis is paid to longitudinal (axial) growth stresses. They largely determine distortion on sawing.

    High magnitude of growth stresses results in Brittleheart in standing trees {Low value corewood}End-splitting in logs {Low recovery of sawn timber}Warping, twisting in sawn boards {Excessive planning wastes and low productivity}

  • Defects due to high growth stressesGrowth stresses causes severe sawing problems in plantation timber and thats the reason we need to study this very important parameter.

  • Pattern and distributionThe distribution of longitudinal growth stress has been observed to vary progressively from tensile at the periphery to compressive at the centre.

    The change from tension to compression is considered to occur at about one third to halfway along the radius from the periphery.

  • How do growth stresses originate in trees??Several theories and hypothesis have been postulated:

    - Weight of the tree (Martley,1928)- Longitudinal cell shortening (Jacobs,1938) - Lignin swelling (Boyd,1985) - Cellulose tension (Bamber, 1979,1987) - Combination of LS and CT (Okuyama, 1993, 2000)

  • Why this study ? Eucalyptus - planted extensively mainly for pulp and paper and fuel wood Utilization of this species is limited due to growth stresses Improvement in both breeding and processing of the plantation grown species is gaining importance. With the clonal forestry gaining significant thrust for quality production, it is desirable to study the variation in growth stresses in different clones. Selection of appropriate clones provide an opportunity to grow trees with pre-defined wood characteristics for future production.

  • ObjectivesUtilization of clonal material of eucalypts and propagation of low stresses clones through evaluation of :

    Variation in growth strains in clones raised by Indian Tobacco company (ITC).Variation of strains with diameter.

  • Materials6 logs of each of five clones obtained from ITC Bhadrachalam in Andhra Pradesh (a southern state in India.)Diameter of the logs- 9 cm to 17 cm.Age at the time of measurements- 8 years

  • Measuring growth stresses

    It is not possible to measure growth stresses directly.

    Growth strains can be measured with greater ease by relieving the stresses.

    The magnitude of released growth strains can be considered an indicator of growth stresses, as stresses are proportional to strains within the elastic region.

    Contd

  • Growth stresses are evaluated by growth strain and modulus of elasticity. For measurement of growth strain there are several techniques:

    (a) Plank stripping method (b) Nicholsons Method (c)The French method (d) The strain gauge method We have measured growth strain using strain gauge method.

    Contd.

    Measuring growth stresses .

  • Longitudinal strains were measured in logs using strain gauges.Strain gauges were glued to the wood surface.Wood fibres were cut above and below the strain gauge to release the growth stresses.Strains were recorded.

    Measuring growth stresses

    Contd

  • Hole diameter (30 mm)

    Hole depth (20 mm)

    Distance between hole edge and strain gauge (10 mm)

    Contd

    Measuring growth stresses

  • Strain measuring indicator

    Measuring growth stresses

  • Advantages of strain gauge method It is less destructive method as compared to other available methods.It is more suitable for measuring longitudinal strain in a very thin layer of wood.Instantaneous recording of the strain value.Compact and suitable for repeated measurement.Measurement can be made at several points simultaneously

    However, it is expensive.

  • Variability between different clones

    Chart2

    876.5273.7476940542273.7476940542

    601.9166666667184.610513424184.610513424

    466180.3751645876180.3751645876

    490.5833333333281.4488260176281.4488260176

    640.0833333333124.4871144604124.4871144604

    Clone Number

    Growth strain (x10-6)

    Sheet1

    Clone -TreeGS Ist sideGS Iind sideTotal 29 Trees

    Average

    A1111511151115

    A211818291005

    A3768245506.5

    A4621621621

    A5985664824.5

    A6129010841187

    B11095522808.5

    B2836766801

    B3688668678

    B4530280405

    B5421421421

    B6528468498

    C1646580613

    C2192160176

    C3541467504

    C4661661661

    C5726280503

    C6426252339

    D1555469512

    D2361361361

    D3624593608.5

    D4316206261

    D5980980980

    D6230212221

    E1737641689

    E2730636683

    E3572252412

    E4725537631

    E5864707785.5

    Sheet1

    0

    0

    0

    0

    0

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    0

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    0

    0

    0

    0

    0

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    Strain on side A

    Strain on side B

    Sheet5

    Anova: Two-Factor Without Replication

    SUMMARYCountSumAverageVariance

    Row 153737.5747.553937.5

    Row 253026605.2112019.2

    Row 352709541.810630.575

    Row 452579515.830655.2

    Row 553514702.854455.325

    Row 652885577141422.5

    Column 165259876.574937.8

    Column 263611.5601.916666666734081.0416666667

    Column 36279646632535.2

    Column 462943.5490.583333333379213.4416666667

    Column 563840.5640.083333333315497.0416666667

    ANOVA

    Source of VariationSSdfMSFP-valueF crit

    With-in clone210020.041666667542004.00833333330.860.522.71

    Between clones641178.6166666674160294.6541666673.300.032.87

    Error971302.5833333332048565.1291666667

    Total1822501.2416666729

    Sheet2

    ABCDE

    11115808.5613512689

    21005801176361683

    3506.5678504608.5412

    4621405661261631

    5824.5421503980785.5

    61187498339221640

    877602466491640

    273.75184.61180.38281.45124.49

    Sheet2

    0273.7476940542273.7476940542

    0184.610513424184.610513424

    0180.3751645876180.3751645876

    0281.4488260176281.4488260176

    0124.4871144604124.4871144604

    Clone No.

    Growth strain (x10-6)

    Sheet3

  • AnalysisANOVA indicates a significant difference in growth strains betweendifferent clones.

  • Difference in strain on two sidesSignificant association between strain measured on one side with the strain on opposite side in logs

    Chart1

    1115

    829

    245

    621

    664

    1084

    522

    766

    668

    280

    421

    468

    580

    160

    467

    661

    280

    252

    469

    361

    593

    206

    980

    212

    641

    636

    252

    537

    707

    Strain on side A (x 10-6)

    Strain on side B (x 10-6)

    Sheet1

    Clone -TreeGS Ist sideGS Iind sideTotal 29 Trees

    A111151115

    A21181829

    A3768245

    A4621621

    A5985664

    A612901084

    B11095522

    B2836766

    B3688668

    B4530280

    B5421421

    B6528468

    C1646580

    C2192160

    C3541467

    C4661661

    C5726280

    C6426252

    D1555469

    D2361361

    D3624593

    D4316206

    D5980980

    D6230212

    E1737641

    E2730636

    E3572252

    E4725537

    E5864707

    Sheet1

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    Strain on side A

    Strain on side B

    Sheet2

    Sheet3

  • Relationship between log diameter and growth strainsNo strong association between log diameter and growth strains

    Chart3

    1115

    1181

    768

    621

    985

    1290

    1095

    836

    688

    530

    421

    528

    646

    192

    541

    661

    726

    426

    555

    361

    624

    316

    986

    230

    725

    737

    572

    864

    730

    Diameter (cm)

    Growth strain (x10-6)

    Sheet1

    14.51115

    13.31181

    16.8768

    13.6621

    13.2985

    13.61290

    13.31095

    12.26836

    13.05688

    12.57530

    11.6421

    13.88528

    12.74646

    11.46192

    12.42541

    9.88661

    9.39726

    9.5426

    10.66555

    10.66361

    11.57624

    9316

    10.66986

    9.88230

    14.33725

    12.1737

    12.1572

    12.1864

    14730

    Sheet1

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    Diameter (cm)

    Strain (micron)

    Released surface growth strain in logs of different diameters

    Sheet2

    A993

    B683

    C532

    D512

    E726

    Sheet2

    0

    0

    0

    0

    0

    Clones

    Longitudinal growth strain (micron)

    Variation in growth strains in different clones

    Sheet3

    A287

    B142

    C184

    D142

    E171

    Sheet3

    0

    0

    0

    0

    0

    Clone

    Difference in strain (micron)

    Difference in strain measured at two sides of the logs

  • ConclusionsGrowth stresses is one of the most important wood quality criteria The study revealed a significant variation in growth strains betweendifferent clones providing an opportunity to select low stress clone for sawn timber production.There was a significant association between strain measured on one side with the strain on opposite side in logs. These suggests that a single measurement of strain on a log could indicate magnitude of stresses for screening purpose.Tree growth as represented by the log diameter does not appear to have any significant association with growth strains.

  • Acknowledgement:IUFRO for SAPFAO for partial fundingICFRE for supporting my workMoEF, Govt. of India Authorities at my instituteDr Andrew wongDr Susan Siau

  • THANK YOU