VII. Alps-Adria Scientific Workshop
Stara Lesna, Slovakia, 2008
OCCURRENCE OF SOIL AND PLANT NEMATODES IN
SOYBEAN UNDER CEREAL ROTATION
1
Marija IVEZIĆ – Ivana MAJIĆ
1
Mirjana BRMEŽ
1
– Marija VRATARIĆ
2
– Emilija RASPUDIĆ
1
–
1
Department of Plant Protection, Faculty of Agriculture, J. J. Strossmayer University of Osijek,
Trg Sv. Trojstva 3, Osijek, Croatia, marija.ivezic@pfos.hr
2
Agricultural Institute Osijek
Abstract: Nematodes are widely distributed in soil and directly under environmental and anthropogenic
influences. The objectives of this study were to determine the population fluctuation of five trophic groups for
two vegetation periods (2005 and 2006) and to observe the differences between the same trophic groups
compared by month between the years. Soil samples were taken twice in soybean vegetative growth stage and
once in reproductive growth stage on 7 cultivars. Total of 39 nematode genus were identified. The most
dominant genus in trophic groups were: Pratylenchus, Aphelenchoides, Rhabditis, Dorylaimus and
Mononchus.The population fluctuation differed for all trophic groups depending on the month and the year.
Significant differences between the years were found among the same trophic groups depending on the month
while all groups except plant parasites significantly differed in October. The significant difference between
the years of total populatuin of nematodes occured in June and October. Overall, plant parasites increased
population in both years indicating soybean as good host plant while the environmental and human factor
probably was the most important influencing factor for the other trophic groups.
Keywords: nematode structure, trophic group, plant parsites, soybean
Introduction
Nematodes represent an important part of the soil microfauna and directly are affected
by environmental and anthropogenic disturbances. According to their feeding strategy,
nematodes could be classified into five the most important trophic groups: plant
parasites (PP), bacterial (BF) and fungal feeders (FF), omnivores (OM) and predators
(PR) (Yeates et al., 1993). Nematodes can be used as bioindicators of conservation or
disturbance, nutrient enrichment and pollution of soils this is particulary important role
since environmental concerns are rising (Beres and Husti, 2006; Dobo et al., 2006;
Várallyay, 2006; Brmez et al., 2007). In response to a human intervention, the structure
of nematode comunity becomes dominated by bacterivores however increase in
numbers of fungivores indicates association of FF with fungal root degradation in soil
(Berkelmans et al., 2003). Soybean (Glycine max L. Merr.) is a globally important
oilseed crop and source of high quality protein and among the various constraints, plant
parasitic nematodes pose treat to demanding high yield production (Sikora and Greco,
1990; Sudaric et al., 2007). Use of soybean resistant cultivars has been exploited
successfully to control to the most important nematodes of soybean Meloidogyne spp.
(root-knot nematode) and Heterodera spp. (cyst nematode). However resistant cultivars
are still not released for the second most important plant parasitic genus, Pratylenchus
spp. (root lesion nematode) which proved to be pathogenic to soybean, since it has
suppressed yields up to about 31% (Schmitt and Barker, 1981). The objectives of this
study were to determine the population fluctuation of nematode trophic groups in
soybean for two vegetation periods (2005 and 2006). Furthermore, to determine the
differences between the same trophic groups compared by month between the years.
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DOI: 10.1556/CRC.36.2008.Suppl.1
Vol. 36, 2008, Suppl.
Cereal Research Communications
Materials and methods
The research was conducted in 2005 and 2006 at the Agricultural Insitute Osijek,
Croatia and set as randomized complete block design. Soil samples were collected in
four replicates on fields (3.5 ha) planted with 7 soybean cultivars. The sampling was
done in June and July in soybean vegetative growth stages and in October during the
reproductive growth stage. The climate of this region in 2005 was characterized in
excess of rainfall during early vegetation period and very dry in October, while in 2006
precipitation was normal to dry. The type of soil was hypogley hydromeliorated soil
(pH 6-6.5; humus 2.2%; 27.4 mg K2O 100 g soil-1; 18.4 mg P2O5 100 g soil-1). The
research fields in 2005 and 2006 were rotated with cereals for two years prior to
soybean planting. Extraction of nematodes from soil was processed following the
Erlenmeyer method (Seinhorst, 1955). Nematodes were identified to the genus level
according to Bongers (1994) and classified into the trophic groups after Yeates et al.
(1993). The data of nematode population were log10 transformed and subjected to the
Duncan’s multiple range tests (P < 0.05). The differences between the population of the
same trophic groups by the month and by the year were tested by the analysis of
variance using the GLM procedure of SAS (SAS Institute Inc., 2000).
Results and discussion
In 168 analyses of soil samples, 39 genus of nematodes were identified and classified
into five trophic groups. Their population fluctuation is showed in Fig 1. and Fig. 2. The
PP appeared as the most dominant group present in 2005 while BF was the most
dominant in 2006. In October 2005 and 2006, the population of plant parasites (PP)
reached the highest peak. This coud indicate that the same conditions that favor soybean
growth are also favorable for PP development. The genus Pratylenchus was the most
dominant in all soil samples for two years and should be monitored continuously in
order to prevent possible yield losses (Schmitt and Barker, 1981).
Figure 1. Population fluctuation of five trophic groups in 2005
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VII. Alps-Adria Scientific Workshop
Stara Lesna, Slovakia, 2008
The population of BF, with the most abundant genus Rhabditis peaked in October
indicating their association with environmental factors and anthropogenic influence
(Brmez et al., 2007). As opposed to the PP and BF, the final population of FF and OM
in October decreased if compared to the initial population in June 2005 and 2006.
Decline might be associated to the low fungal degradation of root tissues prior the
harvest for FF (Gomes et al., 2002) and the possibility of human intervention in the
field prior to the sampling since dorylaimids are sensitive to agricultural practices
(Brmez et al., 2006). Nematodes from genus Aphelenchoides comprised the major
group of FF while Dorylaimus was the most dominant genus amon OM. The PR
(Mononchus as the most dominant genus) population levels were low and stable for the
whole vegetation period, except for peak in October 2005.
Figure 2. Population fluctuation of five trophic groups in 2006
Significant differences were found in October between the same trophic group between the years for
population of all trophic groups except PP (Tab. 1).
Table 1. Comparisons of the same trophic group and total population of nematodes between the months and
the years
June
July
October
Trophic
group
2005
2006
2005
2006
2005
2006
PP
1.65a
1.69a
1.48a
1.79b
1.98a
1.97a
FF
1.40a
1.09a
0.98a
0.78a
0.91a
0.47b
BF
2.10a
1.60b
1.64a
1.44b
2.32a
1.60b
OM
1.17a
1.41a
1.19a
1.24a
0.76a
1.06b
a
b
a
a
a
PR
0.36
0.10
0.05
0.09
0.68
0.09b
TOTAL
2.39a
2.18b
2.10a
2.10a
2.56a
2.29b
*PP – Plant parasites; FF – Fungal feeders; BF – Bacterial feeders; OM – Omnivores; PR – Predators; Row
values within column followed by the same letter are not significantly different as determined by Duncan’s
multiple range test (P > 0.05)
Population of BF was significantly different in all months between two years and this
might be due to agricultural practices and due to different soil humidity between the
years since it was very dry period in October 2005 while in the same period 2006
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DOI: 10.1556/CRC.36.2008.Suppl.1
Vol. 36, 2008, Suppl.
Cereal Research Communications
precipitation was normal. The significant difference between the years was found in
July for PP, when it was extremely wet in 2005 while in 2006 it was dry period. Since,
PP are associated with plant growth, here it might indicate that plants could have been
under drought stress in 2005 and weaken their natural plant defense mechanism that
enabled PP to feed and reproduce intensively. In addition, increase of PP during the
vegetation period suggests susceptibility of soybean to the most dominant group of PP.
Total number of nematodes significantly differed between the years in June and October
when population of nematodes were higher in 2005 compared to the same period in
2006.
Conclusions
Since the population of PP had an increasing tendency towards the end of vegetation
and their reproductive ratio (population final/population initial) was positive it suggests
that soybean cultivars have been good host plant to the most dominant PP genus
Pratylenchus. Environmental effect as well as human intervention in the fields might be
the most important factor influencing population of other trophic groups but it remains
speculative since these effects were not studied in this research.
Acknowledgements
This research was conducted within the project financed by the Ministry of Science,
Education and Sport of Republic of Croatia.
Reference samples
Beres, K. – husti, I.: 2006. Alternative indicators in food chain according to life quality and sustainability.
Cereal Research Communications, 34: 1. 801-804.
Berkelmans, R. - Ferris, H. - Tenuta M. - van Bruggen, A.H.C.: 2003. Effects of long-term crop management
on nematode trophic levels other than plant feeders disappear after 1 year of disruptive soil management,.
Applied Soil Ecology, 23: 223–235.
Bongers, T.: 1994. De nematoden van Nederland. KNNV: Utrecht, 408
Brmez, M. - Ivezic, M. - Raspudic, E.: 2006. Effect of mechanical disturbances on nematode communities in
arable land. Helminthologia, 43, 2: 117-121.
Brmez, M. - Ivezić, M. - Raspudić,E. - Tripar,V.- Baličević,R.: 2007. Nematode communities as bioindicators
of antropogenic influence in agroecosystem. Cereal Reserach Communications, 35: 2. 297-300.
Dobo, E –Fehete-Farkas, M. – Kumar Singh M. – Szucs, I.: 2006. Ecological-economic overview. Cereal
Research Communications, 34: 1 777-781
Gomes, S.G. - Huang, S.P. - Cares, J.E.: 2002. Nematode community, trophic structure and population
fluctuation in soybean fields. Fitopatol. bras, 28: 3 258-266.
SAS/STAT User's Guide.: (2000). Version 8. Cary, NC, SAS Institute Inc
Schmitt, D.P. - Barker K.R.: 1981. Damage and reproductive potentials of Pratylenchus brachyurus and
Pratylenchus penetrans on soybean. Journal of Nematology, 13: 327-332
Seinhorst J.W.:1955. Een eenvoudige methode voor het afscheiden van aaltjes uit grond. Tijdschr. Plziekt. 61,
188-190
Sikora, R.A.–Greco, N.: 1990. Nematode parasites of food legumes. InM.Luc, R.A. Sikora, and J.Bridge eds.
Plant parasitic nematodes in tropical and subtropical agriculture.Wallingford,UK: CAB International,
181-235
Sudaric, A., - Vrataric, M., - Rajcan, I.: 2007. Sustainability the food chain over genetic improvement of the
quantity and quality of soybean grain. Cereal Research Communications, 35: 2.1105-1108.
Várallyay, G.: 2006. Life quality – soil – food chain. Cereal Research Communications, 34: 1. 5-8.
Yeates, G.W. - Bongers, T. - de Goede, R.G.M. - Freckman D.W. - Georgieva, S.S.: 1993. Feeding habits in
soil nematode families and genera—an outline for soil ecologists, Journal of Nematology, 25: 315–332.
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