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Interaction of Scutellonerna cavenessi and Glo~nusmosseae
on growth and N, fixation of soybean
Gaetano GERMANI*, Bernard OLLIVIER* * and Hoang Gia DIEM* *
* Laboratoire de Nélnatologie and * * Laboratoire de Microbiologie,
ORSTOM, B.P. 1386, D a k a r , Sénégal.
SUMMARY
The influences of a parasitic nematode (Scutellonema cavenessi) and a vesicular arbuscular mycorrhiza ( G l o m u s
mosseae) alone or in combination on growth and N, fixation of one cultivar of soybean (44 A73) were studied in
the greenhouse. In combined inoculationsof soybean with G. wosseae and S. cavenessi, development of mycorrhizae
nullified the stunting and the reduction
of N, fixation caused by the nematode. Growth andN, fixation of mycorrhizal plants were greater t h a n t h a t of non mycorrhizal plants.
RÉSUMÉ
Interaction de Scutellonema cavenessi et Glomus mosseae sur la croissance et la fixation de N , du soja
Les auteurs exposent les résultats de l’inoculation simple et combinée du nématodeScutellonema cavenessi et de
l’endomycorhize Glomus mosseae sur le cultivar de Soja 44 A73. Des mesures ont été effectuées au 46e jour du
cycle végétatif : elles portaient sur ( 1 ) le poids et la teneur en N et P de parties aériennes ( 2 ) le nombre et le poids
des nodules bactériens (3) la fixation de N, (4) l’infection par les nématodes et parles endomycorhizes. Les valeurs
des paramètres étudiées sont significativement diminuées par
S . cavenessi et significativement au.gmentées par
G. mosseae. Dans le cas d’une inoculation combinée des deux organismes, l’effet négatif des nématodes est inhibé
: les valeurs des parametres considérées ne sont pas différentes
celles
de observées
par l’effet bénéfique des mycorhizes
sur des plantes inoculées avec des mycorhizes seules.
Studies on plant parasitic nematode-endomycorrbizainteractionshave
been recently discussed inmany reviews (Menge et al., 1977 ;
Schenck & Kellam, 1978 ; Schonbeck, 1979).
O’Bannon et al. (1979) andO’Bannon and Nemec
(1979)baveshown
thatstimulation of Citrus
growth by Glomus rnosseae or Glonzus etunicatus
was to Some extent reduced in the presence of
Tylenchulus semipenetrans or Radoplzolus similis.
However,
mycorrhizal
plants
parasitized
by
nematodesalways
grow betterthanplants
infectedwithnematodesalone(Atilano
et al.,
1976 ; Roncadori & Hussey, 1977 ; Hussey &
Roncadori, 1978 ; O’Bannon et al., 1979).
Other papers (Schenck& Kellam, 1978) have also
shown variation in host responset o a nematodemycorrhizal complex.
The effect of nematodes on the behaviour of
vesicular-arbuscularmycorrhizal(VA)fungi
is
also variable. It may be defrimental (Schenck &
’
Revue Nématol. 4 (2): 277-280 (1981)
Kinloch,1974 ; Schenck,Kinloclr & Dickson,
1975)without
effect (Atilano et al., 1976 ;
Hussey & Roncadori,
1978)
or
stimulative
(Bagyaraj,Manjunath & Reddy,1979).
. Many
papers
have
reported
significantly
reducednumbers
of root-knotnematodes
or
reducedformation
of root-gallsindifferent
plants
preinoculated
with
Glomus mosseae,
Glomus
fasciculatus
or Glornus
macrocarpus
(Silrora St Schonbeck
1975
; Sikora
1978
;
Silrora,1979 ; Bagyaraj, Manjunath & Reddy,
1979 ; Kellam & Schenck,1980).Inversely,
other workers have reported greater populations
of root knot larvae in mycorrhizal plants
than
in non mycorrhizal plants (Rich & Bird, 1974 ;
Atilano et al., 1976).
Preliminary works haveshown thatunder
controlled conditions in the laboratory, Scutellonerna cavenessi Sher, 1963 may severely affect
growth and N, fixation of soybean and peanut
277
G. Germani, B . Ollivier & H . G . D i e m
(Germani, Diem & Dommergues,1980 ; Germani, 1981). It has been recently shown t h a t N,
fixation of two cultivars of peanuts was reduced
to different
degrees
b yt h e
presence of S .
cavenessi in fields studies(Germani,198lb).
Thepresentstudyhasbeendesignedto
determine the effect of the dual inoculation with.
Glomus
mosseae
and Scutellonema
cavenessi
on growth and nitrogen fixation of one cultivar
of soybean.
Material and methods
- -
Five-day-old seedlings of soybean cv. 44 A 73
germinatedin Sand were transplantedsingly
into 20 cm Clay pot containing autoclaved soil.
The soilwas a sandy soil from the ORSTOM
CenterinDakar(clay3.3%
; silt 4.4%, sand
92.1”,(o; p H : 7.1 ; available P (Olsen) : 104 ppm).
The S . cavenessi inoculumwasprepared
by
extractionfromnaturallyinfested
soil under
field conditions. The nematodes were extracted
bythe Dalmasso’s(1966) simplified technique
and observations were made to ensure that t.he
inoculumwasfreefromotherpathogens.The
extractecl nematodes were then washed several
timesinsterilized
deionized water.
At the timeof transplantion, 5 O00 nematodes
wereadded tothe soil. Plantsdesignatedto
becomemycorrhizal
were inoculatedwith
a
small pad of spores, hyphae and infected root
segmentsobtainedfrom
a Vignaun.guiculata
infectedwith Glomusmosseae. Soybeanplants
of al1 treatments, including
controls,
were
inoculated wit<h a liquid culture of R h i z o b i u m ,
strain USDA 138. Plants designated t o become
non mycorrhizal were similarly inoculat,ed wit,h
mycorrhized inoculum washings passed through
a 50 pm sieve and a Whatnlan N o 1 filter paper
t o standardize microflora.
Treat,mentsconsisted
of inoculationswith
Glomzzsmosseae or S. cauenessi alone,inoculat.ions withboth,andcontrolsinoculatedwith
‘Rhizobium only.
Treatments were replicated seven times and
arrangedin a completelyrandomizeddesign.
Pots were
watered
daily
and
stored
under
greenhouse conditions. 46 days after inoculation
plants were harvested. Roots were cleared and
stained
-.according
of Phillips
and
-- -to
- the
- - method
- ._
2,78
Hayman (1970) the percentage of root segments
infected was then determined on more than100,
3.5 mm length root segments under a dissecting
microscope ( x 65). Nematodes populationsin the
soil and in the root were estimateda t t h eend of
the experiment.
Nematodes were extractedfrom
fresh soil
samplesbyelutriation(Seinhorst,1962)
and
from roots by mist chambers (Seinhorst, 1950),
Nematodes were expressed as numbers per pot.
The effect fo nematode-mycorrhizaonplant
growth was expressed bythedry
weight of
shootsmeasured at, harvest after 48 h a t 800.
P contents and N contents of dried material of
shoots were measured
respectively
by
the
.
vanadate-molybdate
method
(Jackson,
1964)
and
the
Kjeldhal
met.hod.
N, fixation
was
estimated by the dry weight
of nodules measured
after 48 h a t 800 and by the acetylene reduction
method
(ARA)
on
nodulated
roots
held in
hermetically closed serumbottles. Al1 results
wereanalyzedstatisticallyusingtheMannWhitneytest(Snedecor
& Cochran,1967).
Results and discussion
,
Data
in
Table
1 show t h a t S . cauenessi
signifcantly affected growth and nitrogen fixation of the host plant
as compared t o uninoculated plants. As expected, mycorrhizae plant,s
grew better (Fig. 1) and fixed more N, than non
mycorrhizal plant (Tab. 1).
In the dual inoculation treatment (nematode
infected mycorrhizal plants), shoot .and nodules
dry weight,, Nand 4’ contentandARAper
plant were statistically similar t o t.hat found in
plants inoculated with G . mosseae alone. Atilano
et al. (1 976),O’BannonandNemec(1979),
Kellam
and
Schenck
(1980)
have
already
indicated that the presence of VA mycorrhizal
fungi reduce the deleterious activity
of nematodes, however, in ‘their experiment the
beneficial effect of VA mycorrhiza did not completely
compensate forthe damage caused bynematodes..
This
experiment
suggests
t h a t growth of
nematode infected mycorrhizal plants is governed b y a balancebetweeninhibitoryfactors
(nematode)andstimulatoryfactors
(VAmycorrhizae).Thestate
of thebalancedepends
on
the host plant, the nematodes and
VA mycorrhizae
andsoilenvironment.
_ -fungusinvolved,
-~ _ . - - - ,
~
Revue Nématol. 4 ( 2 ) : 277-280 (1981)
:
._
Scutellonema cavenessi, Glornus rnosseae and N , firation of soybean
Table 1
Effect of single and combined inoculations witll Scufellonenm cavenessi
and Glomus rnosseae o n growth and N, fixation of soybean cv. 44 A73
dry m f .
(9)
N o ne
S . cavenessi
G. mosseae
S . cavenessi
$. G . mosseae
2.7 a
1 b
4.3 c
3.6 c
N
P
( w l p(l m
a ng tl )p l a n f )
57 a
17 b
nunlber
dry
mt.
(UV)
125 c
‘2.0 a
0.8 b
5.8 c
84.5 a
35.3 b
98.0 a
100 c
5.1 c
70.5
c313a
hlycorrhizal
Nematodes
infection
nn~oleslplant root segments
nurnber
infested ( yo) perplant
A Rd
Nodules
SllOOtS
109 a
29.3 b
320 c
3.9 a
0.6 b
G a
49.6 a
7.4 a
33.6 b
8 700 a
15 DO0 a
Values followed by the same letters are rlot significantly different [ P : .06).
Fig. 1. Effect of single or double inoculation wit,h S. cavenessi and G . mosseae
on growth of soybean : S. cadenessi ( N ) ; control non inoculated ( C ) ; S. cauenessi
and G . rnosseae ( N M ) ; G. mosseae (M.).
Thepresentwork
shows thattheharmful
effect of plantparasiticnematodemay
be
suppressed by the presence of VA mycorrhizae
assuggested bystatisticalanalysis(Tab.
1) :
nematode
infected
mycorrhizal
plants
grow
as well as plant infected with G. mosseae alone.
The improved grow:h of plants inoculated with
both S . caverressi and G. mosseae %vas probably
due to
the
well-known beneficial effect of
mycorrhizae alone without any apparent interactionwithnematodes.Similarobservations
have been madebyRoncadoriandHussey
(1977),
Hussey
and
Roncadori
(1978)
and
O’Bannon et al. (1979). There is no effect of VA
mycorrhizaonthepopulation
of S . cavenessi
but lower mycorrhizalinfection \vas observed
Revue NC1rdol. 4 (2): 277-280 (1981)
in mycorrhizal plant inoculated with nematodes
ascomparedtohealthymycorrhizalplants.
Conclusion
In theexpriment
carried o u t inoculation
with nematodes alone exerted a negative effect
ongrowthand
N, fixation of soybean ; this
effec.t was inhibited b y mycorrhizalinfection
to such an estent {bat there was no significant
difference
between
plants
jointly
inoculated
withnematodesand
G. mosseae and,plants
inoculated with G. mosseae alone. This work inaddition to tbat of many others on the
effect
of nematode-VAmycorrhizainteractions
on
279
G. Germani, B. Ollivier h H . G . D i e m
PI-IILLIPS,
J.hI. & HAYMAN, D.S. (1970).Improved
procedures for clearing roots and staining vesicular
arbuscular mycorrhizal fungi for rapid assessment
of
infection. T r a n s . br. mycol. Soc.,,55 : 155-161.
RICH, J.R.6r BIRD,G.W. (1974). Association of earlyseason VA mycorrhizae and increased growth and
development of cotton. Phytopathology, 64 : 14211425.
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Accepté pour publicafion le 1 8 m a i 1981.
280
Revue Nématol. 4 (2): 277-280 (1981)