Growth Efficiencies of Diverse Pinus taeda families as affected by Genetics of the Root system James...
-
Upload
peregrine-williams -
Category
Documents
-
view
214 -
download
1
Transcript of Growth Efficiencies of Diverse Pinus taeda families as affected by Genetics of the Root system James...
Growth Efficiencies ofDiverse Pinus taeda families
as affected byGenetics of the Root system
James E. Grissom and Steven E. McKeandDepartment of Forestry
North Carolina State University,Raleigh, NC, U.S.A.
Objectives
Evaluate genetic effects of Roots upon Aboveground Growth process
Determine whether Root system can alter Stemwood production; under what conditions
Identify physiological traits related to Root effects on Stemwood production
Materials and Methods
Loblolly pine seedlings from 2 contrasting provenances;10 OP families; 5 from fast-growing (ACP) prov. and 5 from slow-growing (LPT) prov.
total 1800 seedlings
Grafted reciprocally (fast type onto slow type, and vice versa)
All possible combinations of genotypes
Grafted at 12 weeks of age (June 1997)
Out-planted at 40 weeks of age (January 1998),on a sandy infertile site in Scotland County, NCPlanted in split plot layout, of 6 blocks, full set of 150 trees per sub-plot ;
half of the plots were fertilized by hand, twice each year.
Fertilizer applications:Elemental dosage (kg/ha)
Month N* P K Fe B Cu ZnMarch 50 23 40 0.5 -- -- --June 50 23 40 0.5 0.1 0.2 0.2
* N - total 10% composed of 6% urea + 4% ammoniacal
Methods
After two growing seasons, in early October 1999,
Tree heights and diameters were measured,
Roots were dug up and seedlings harvested.
Methods
Total numbers of harvested seedlings:
Type Fast-grow Slow-grow GRAFTED 260 260NON-GRAFTED 40 40
300 + 300
Roots were washed, dried and weighed.
Stems, branches and leaves were separately dried in 70oC oven for 72 hours, and then weighed.
Methods
Leaf Physiology:
Methods
Gas Exchange Instantaneous Portable Photosynthesis
System (Li-Cor LI-6400)
Carbon isotope Integral Mass spectrometry
composition (Finnigan Isotope Ratio Mass Spec.)
Weather Data:
13.1”
7.9”
-5.2”
-10
-5
0
5
10
15
NormalMay-Aug.
ActualMay-Aug.
Deficit
During Summer of 1999, moderate droughtoccurred in central North Carolina:
TotalRainfall(inches)
0
300
600
900
1200
Rootstock type
Fast Slow
= SLOW
= FAST
Fast Slow
Total
Biomass
(g)
|-- Fast --| |-- Slow --| Top (scion)
Total Plant Biomass, Grafted Trees,Fertilized treatment, aged 2 years
450
300
150
0
150
300
450
600
750
900
Rootstock type
Mas
s (g
)For Fast-growing seedling top:
Fast Slow
Above-ground
Below-ground 450
300
150
0
150
300
450
600
750
900
Rootstock type
Ma
ss
(g
)
= SLOW= FAST
For Slow-growingseedling top:
Fast Slow
Biomass Allocation :
Stem Growth Efficiencies, Grafted treesFertilized treatment
0.0
0.2
0.4
0.6
0.8
1.0
Fast Slow
Rootstock
FAST SLOW
Fast Slow
|-- Fast ---| Top |-- Slow --| Stem mass
Leaf mass
ANOVA:Source P-value
Top (scion) 0.01
Rootstock 0.09
(g/g)
Water Use Efficiency of shoot of Fast-growing family is Raised when grown on Slow-growing Rootstock.
Ph
oto
syn
thet
ic
Rat
e ( u
mo
l/m2/s
ec)
Leaf Water Conductance ( mol /m 2/sec)
Steeper slope means greater efficiency
Rootstock type:
SLOW FAST
4
5
6
7
8
9
10
0.06 0.08 0.10 0.12 0.14 0.16
Carbon Isotope Discriminationby Graft Class, Fertilized treatment
18
19
20
21
22
FAST SLOW
Fast Slow
Rootstock
Fast Slow
|-- Fast ---| Top |-- Slow ---|ANOVA:Source P-value
Top (scion) 0.035
Rootstock 0.006
(%o)
Growth Efficiency vs.Carbon Isotope Discrimination
0.5
0.6
0.7
0.8
0.9
1
19.0 19.5 20.0 20.5 21.0
C Isotope Discrimination (%%)
Gro
wth
Eff
icie
ncy
s:Fastr:Slow
FastFast
SlowSlow
SlowFast
Higher Water Use Efficiency (?)
Summary of Important Results
Rootstocks can substantially impact allocation of mass to aboveground parts, including the main stem.
When fertilized, fast-growing provenance attains large mass both above- and below-ground, even when grafted to a slow-growing counterpart.
Biomass Allocation
Summary of Important Results
Stem Growth Efficiency is affected more by Scion stock, but Water Use Efficiency is affected more by Root stock.
Efficiency of Foliage
Conclusions
Genetic factors in Roots can alter Growth Efficiency, when soil nutrients are adequate for growth.
Growth Efficiency appears related to Water Use Efficiency, among genetic families.
Carbon isotope (13C) content in leaves shows promise as a physiological marker for “Efficiency of Foliage”.