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Competition between Glomus tenue and some coarse fungi for colonizing red clover roots in acid soils
33?
Agriculture, Ecosystems a n d Environment, 29 (1989) 337-340 Elsevier Science Publishers B.V., Amsterdam Printed in Czechoslovakia
C O M P E T I T I O N BETWEEN G L O M U S TENUE AND SOME COARSE FUNGI FOR COLONIZING RED CLOVER ROOTS IN ACID SOILS Sainz, M.J.*, Vilariflo, A. and Arines, J. Unidad
Estructural
de
Fisiologia
Vegetal,
institute
de
lnvestigaciones
Agrobiol6gicas de Galicia (CSIC), Apanado 122, F-15080-Santiago de
Compostela,
Spain * Departamento de Agrieultura. Facultad de Veterinaria, E-27002-Lu8o, Spain ABSTRAcr A greenhouse trial was carried out to study the competitive interactions between Giomus
tenue and three coarse fungi (G. fasciculatum, G.
macroearpum
and G. masseae) for colonizing red clover roots in three acid ~,~ils under different fertility
conditions.
G.
tenue did not infect the reels when inoculated with G .
fasciculatum
in any of the soils, but caused most of the mycorrhizal infection
when mixed
with G.
macrocarpum.
Competitiveness
among
all
vesicular-
arbuscular mycorrhizal fungi studied were strongly affected by soil fertility. INTRODUCTION Glomus tenue, widely known in mycorrhizal studies as the fine endophyte,
has usually been found in acid soils. This vesicular-arbuscular (VA) mycorrhizal fungus is easily recognized in roots by its infections pattern, consisting of smaller vesicles and finer hyphae than those of VA mycorrhizal fungi referred to as coarse endophytes. The effectiveness of G. tenue to improve plant growth and nutrition has been studied by several authors, but few papers have dealt with its competition with other VA mycorrhizal fungi to colonize plant roots. The aim of the present work was to examine the infec:ing capacity of G. tenue when in mixed
inocula
fasciculatum and G.
with one of three coarse fungi, namely G. macrocarpum.
applied
mosseae, G .
338
MATERIAL AND METHODS
Three acid soils (At)ella, Castro and Xinzo soils), with high organic matter content and low P content (except Xinzo soil), were steam-sterilized and amended with Ca (OH) 2 and phosphorus to achieve different fertility levels (Table I). Three VA
myco~rhizal
inocula,
consisting
of
spores,
mycelium
and
infected
root
fragments, were separately tested. Each inoculum was a mixed culture of G. tenue with one
coarse endophyte
(G.
mosseae, G. fasclculatum or G.
macrocarpum).
Fifty grammes of each inoculom per pot were mixed with the soil. Each pot, containing 700 g of soil, received a filtrate from the corresponding unsterilized soil to ensure a common microfiora. Red clover ( T r i f o l i u m p r a t e n s e
L.) was
chosen as host plant. Af!er see4 germination, the number of plants per pot was thinned to three. Four months after sowing, plants were harvested and roots washed free from soil. Mycorrhizal infection in roots was assessed by the gridline intersect method (Ambler and Young,
1977)
after clearing and
staining
(Phillips
and
Hayman, 1970). The percentages of microscope fields with only fine (%F) or fine+coarse (%FC) mycorrhizal infections were also examined.
RESULTS AND DISCUSSION
Competitiveness between G. clover roots depended on soil presence of G. tenue (Xinzo
with
mycorrhizal
G.
root
and
mosseae
and G, :enue
fertility (Table 2).
for colonizing red
Liming improved the
in a low P soil (Abella), but depressed it in a high P soil
rousseau).
colonization
When by
condition. This inability of G. tenue
competing G.
tenue
against was
G. f a s c i c u l n t u m ,
no
found in any soil-fertility
to colonize plant roots when G. fasciculatum
is present has also been described by Abbott and Robson (1985) and LopezAguillon and Mosse (1987). When
the inoculum consisted of G. tenue + G .
macrocarpum, however, C-.. tenue was the dominant endophyte in roots.
339
Several authors have stressed the need to introduce mixcd inocuJa in soils to
guarantee
interactions
crop
improvement.
between
fungal
Our
results
components
in
outline
planning
the
importance
mixed
inocula,
of studying especially
relation to the fertility conditions o f each soil. Table
I.
Amendments or soils and
pH
and
assimilable P*
(ppm)
values
reached at the pre-cowing time.
_ Amendment
nH
p
Nil (TO)
5.0
3
Liming (TI)
6.1
2
Phosphate fcrtilization (T2)
$.1
15
6.0
13
.H
P
5.7
3
Xinxo
nH
P
3.I
II0
5.7
!i0
Liming and phosphate fertilization (1"3)
5.7
14
* Assimilable P extracted with the Mehlich (1978) solution.
Table 2. Percentage of microscopic fields with only fine (%F) or fine ,
Soil
Abella
Soil fertility
G. teaue +
condition~
G. m o ~
TO
TI
T2
13
Castro
TI
1"3
Xinzo
coarse ( ~ F C ) mycorrhizai infection.
3'2
~.
fa~cicula#unI
G. tenue ÷
G. m n c r ~ c a r n u m
~F
nd
0
0
%FC
ud
0
0
~P
56 ~L 10.0
0
53 4. 6.4
~/:~
24 +
0
26 ~
4.0
6.1
~F
0
0
58 ~ 19.6
c~J:C
0
0
28 +
6.9
0
89 4.
6.0
11 +
6.0
~P
20 + 12,0
%FC
14 :k. 5..5
1 + 1.0
~P
! :E 1.0
0
75 4. 21.4
%!:C
! :t.
1.0
0
19 :It: 9.9
~F
25 4. 10.8
2 4. 1.2
88 4. 10.3
~i~
15 4- $.S
2 4. 12
12 4. 10.3
%F
3] + 12.7
%!:C 3"3
G . ~enoe +
2:1:.
1.0
0
51 :t. 13.6
0
31 .I.
1.5
%F
0
0
86 4. 2.1
%i:C
0
0
14 .I.
2.1
in
340 REFERENCT.S
ABBOTT, L.K.o ROBSON, A.D.: The effect of soil pH on the formation of VA mycorrhizas by two species of Glomus. Aust. J. Soil Res. 23: 253-261, 1985.
AMBLER, LR., YOUNG, J.L.: Techniques for determini.g root length infected by vesicular-arbuscular mycorrhizas. Soil Sci. Soc. Am. J.
41: 551-556, 1977.
LOPEZ-AGUILLON, R., MOSSE, B.: Experiments on competitiveness of three endomycorrhiza| fungi. Plant and Soil
97: 155-170, 1987.
MEHLICH, A.: New extractant for soil test evalation of phosphorus, potassium, magnesium, calcium, sodium, manganese and zinc. Commun. in Soil and Plant Anal. 9: 477-492, 1978.
PHILLIPS, J.M., HAYMAN, D.S.: Improved procedures for clearing roots and staining
parasitic
and
vesicular-arbuscular
mycorrhizal
fungi
for
rapid
assessment of infection. Trans. Br. Mycol. Soc, 55: 159-161, 1970.
Sainz, H . J . , Vllarino, A. and Arines, J . , 1989: Competition between ~ and some c o a r s e f u n g i for colonizing red clower roots in acid ~oils. &grl6. Ecosystems Environ. 2 9 : 337-340.
Agriculture, Ecosystems a n d Environment, 29 (1989) 337-340 Elsevier Science Publishers B.V., Amsterdam Printed in Czechoslovakia
C O M P E T I T I O N BETWEEN G L O M U S TENUE AND SOME COARSE FUNGI FOR COLONIZING RED CLOVER ROOTS IN ACID SOILS Sainz, M.J.*, Vilariflo, A. and Arines, J. Unidad
Estructural
de
Fisiologia
Vegetal,
institute
de
lnvestigaciones
Agrobiol6gicas de Galicia (CSIC), Apanado 122, F-15080-Santiago de
Compostela,
Spain * Departamento de Agrieultura. Facultad de Veterinaria, E-27002-Lu8o, Spain ABSTRAcr A greenhouse trial was carried out to study the competitive interactions between Giomus
tenue and three coarse fungi (G. fasciculatum, G.
macroearpum
and G. masseae) for colonizing red clover roots in three acid ~,~ils under different fertility
conditions.
G.
tenue did not infect the reels when inoculated with G .
fasciculatum
in any of the soils, but caused most of the mycorrhizal infection
when mixed
with G.
macrocarpum.
Competitiveness
among
all
vesicular-
arbuscular mycorrhizal fungi studied were strongly affected by soil fertility. INTRODUCTION Glomus tenue, widely known in mycorrhizal studies as the fine endophyte,
has usually been found in acid soils. This vesicular-arbuscular (VA) mycorrhizal fungus is easily recognized in roots by its infections pattern, consisting of smaller vesicles and finer hyphae than those of VA mycorrhizal fungi referred to as coarse endophytes. The effectiveness of G. tenue to improve plant growth and nutrition has been studied by several authors, but few papers have dealt with its competition with other VA mycorrhizal fungi to colonize plant roots. The aim of the present work was to examine the infec:ing capacity of G. tenue when in mixed
inocula
fasciculatum and G.
with one of three coarse fungi, namely G. macrocarpum.
applied
mosseae, G .
338
MATERIAL AND METHODS
Three acid soils (At)ella, Castro and Xinzo soils), with high organic matter content and low P content (except Xinzo soil), were steam-sterilized and amended with Ca (OH) 2 and phosphorus to achieve different fertility levels (Table I). Three VA
myco~rhizal
inocula,
consisting
of
spores,
mycelium
and
infected
root
fragments, were separately tested. Each inoculum was a mixed culture of G. tenue with one
coarse endophyte
(G.
mosseae, G. fasclculatum or G.
macrocarpum).
Fifty grammes of each inoculom per pot were mixed with the soil. Each pot, containing 700 g of soil, received a filtrate from the corresponding unsterilized soil to ensure a common microfiora. Red clover ( T r i f o l i u m p r a t e n s e
L.) was
chosen as host plant. Af!er see4 germination, the number of plants per pot was thinned to three. Four months after sowing, plants were harvested and roots washed free from soil. Mycorrhizal infection in roots was assessed by the gridline intersect method (Ambler and Young,
1977)
after clearing and
staining
(Phillips
and
Hayman, 1970). The percentages of microscope fields with only fine (%F) or fine+coarse (%FC) mycorrhizal infections were also examined.
RESULTS AND DISCUSSION
Competitiveness between G. clover roots depended on soil presence of G. tenue (Xinzo
with
mycorrhizal
G.
root
and
mosseae
and G, :enue
fertility (Table 2).
for colonizing red
Liming improved the
in a low P soil (Abella), but depressed it in a high P soil
rousseau).
colonization
When by
condition. This inability of G. tenue
competing G.
tenue
against was
G. f a s c i c u l n t u m ,
no
found in any soil-fertility
to colonize plant roots when G. fasciculatum
is present has also been described by Abbott and Robson (1985) and LopezAguillon and Mosse (1987). When
the inoculum consisted of G. tenue + G .
macrocarpum, however, C-.. tenue was the dominant endophyte in roots.
339
Several authors have stressed the need to introduce mixcd inocuJa in soils to
guarantee
interactions
crop
improvement.
between
fungal
Our
results
components
in
outline
planning
the
importance
mixed
inocula,
of studying especially
relation to the fertility conditions o f each soil. Table
I.
Amendments or soils and
pH
and
assimilable P*
(ppm)
values
reached at the pre-cowing time.
_ Amendment
nH
p
Nil (TO)
5.0
3
Liming (TI)
6.1
2
Phosphate fcrtilization (T2)
$.1
15
6.0
13
.H
P
5.7
3
Xinxo
nH
P
3.I
II0
5.7
!i0
Liming and phosphate fertilization (1"3)
5.7
14
* Assimilable P extracted with the Mehlich (1978) solution.
Table 2. Percentage of microscopic fields with only fine (%F) or fine ,
Soil
Abella
Soil fertility
G. teaue +
condition~
G. m o ~
TO
TI
T2
13
Castro
TI
1"3
Xinzo
coarse ( ~ F C ) mycorrhizai infection.
3'2
~.
fa~cicula#unI
G. tenue ÷
G. m n c r ~ c a r n u m
~F
nd
0
0
%FC
ud
0
0
~P
56 ~L 10.0
0
53 4. 6.4
~/:~
24 +
0
26 ~
4.0
6.1
~F
0
0
58 ~ 19.6
c~J:C
0
0
28 +
6.9
0
89 4.
6.0
11 +
6.0
~P
20 + 12,0
%FC
14 :k. 5..5
1 + 1.0
~P
! :E 1.0
0
75 4. 21.4
%!:C
! :t.
1.0
0
19 :It: 9.9
~F
25 4. 10.8
2 4. 1.2
88 4. 10.3
~i~
15 4- $.S
2 4. 12
12 4. 10.3
%F
3] + 12.7
%!:C 3"3
G . ~enoe +
2:1:.
1.0
0
51 :t. 13.6
0
31 .I.
1.5
%F
0
0
86 4. 2.1
%i:C
0
0
14 .I.
2.1
in
340 REFERENCT.S
ABBOTT, L.K.o ROBSON, A.D.: The effect of soil pH on the formation of VA mycorrhizas by two species of Glomus. Aust. J. Soil Res. 23: 253-261, 1985.
AMBLER, LR., YOUNG, J.L.: Techniques for determini.g root length infected by vesicular-arbuscular mycorrhizas. Soil Sci. Soc. Am. J.
41: 551-556, 1977.
LOPEZ-AGUILLON, R., MOSSE, B.: Experiments on competitiveness of three endomycorrhiza| fungi. Plant and Soil
97: 155-170, 1987.
MEHLICH, A.: New extractant for soil test evalation of phosphorus, potassium, magnesium, calcium, sodium, manganese and zinc. Commun. in Soil and Plant Anal. 9: 477-492, 1978.
PHILLIPS, J.M., HAYMAN, D.S.: Improved procedures for clearing roots and staining
parasitic
and
vesicular-arbuscular
mycorrhizal
fungi
for
rapid
assessment of infection. Trans. Br. Mycol. Soc, 55: 159-161, 1970.
Sainz, H . J . , Vllarino, A. and Arines, J . , 1989: Competition between ~ and some c o a r s e f u n g i for colonizing red clower roots in acid ~oils. &grl6. Ecosystems Environ. 2 9 : 337-340.