| |
|
Suárez, S.1, Chaves,
E.2 & Clausen, A.M.2
1Facultad de Ciencias Agrarias,
Universidad Nacional de Jujuy;
2Unidad Integrada EEA Balcarce, INTA-FCA,
UNMdP. Balcarce, Argentina.
email:suarezcarrizo@yahoo.com.ar |
|
|
Materials
Andean potato landraces: 11 landraces were
evaluated with 18 replicates/landrace in a completely randomized
design.
Wild species: nine accessions of
Solanum acaule, S. infundibuliforme and S.
megistacrolobum were evaluated with 50 plants/accession;
genotypes that did not exhibit galls after one cycle of infection were
micro-propagated and re-evaluated.
Inoculum: a population of N.
aberrans from Coctaca (3500 m altitude), province of Jujuy,
was employed to evaluate potato landraces and wild species.
Cultivars: 'Spunta', 'Kennebec' and 'Frital
INTA', were evaluated utilizing a nematode population from Mar del
Plata (24 m altitude), province of Buenos Aires. |
|
Figure 1. Click on the picture to enlarge
Figure 2. Click on the picture to enlarge
Figure 3. Click on the picture to enlarge
Figure 4. Click on the picture to enlarge |
|
Methods
Infected soil was employed and the plants were
grown in a screenhouse (Fig. 1). The following variables were
registered: number of galls, number of galls/fresh root weight (g),
number of individuals/fresh root weight (g), and reproduction factor
(R= Pf/Pi),
were Pf =final population and Pi =
initial population.
Nematode races were determined following
Castiblanco et al.(1999) and the Society of Nematologists (http://nematode.unl.edu/pest27.htm)
classificatory schemes.
The extraction of nematodes was performed
according to the method of Coolen and D´Herde (1972); the number of
second juvenile (J2) and female
adults was estimated under a microscope.
Analyses of variance and means by least
significance difference (LSD, 5%), were performed using SAS/STAT. Results and Discussion
The N. aberrans population from Coctaca
corresponds to Race 2. Significant differences were detected in the
landraces regarding number of galls, number of galls/fresh root weight,
number of individuals/fresh root weight and reproduction factor (Pf /Pi)
as can be observed in Fig. 2.
'Tuni blanca' differed significantly from all the landraces, while
'Azul' presented the lowest number of galls. On the other hand, 'Tuni'
and 'Chacarera' presented a low number of galls/fresh root weight,
while 'Azul', 'Cuarentona', 'Collareja' and 'Moradita' differed
significantly from the other landraces for number of individuals/
fresh root weight. 'Azul' presented the best performance for
reproductive factor; this landrace has the lowest values for three of
the four variables registered.
Variability was observed in the wild species studied considering the
variables registered. The screening of the genotypes that escaped
initial infection is presented in Fig. 3 with 'Tuni' included as
susceptible control.
One genotype of Solanum megistacrolobum (Oka 6727: 283) and two of
Solanum acaule (CCS 1244: 284-286), presented the best behavior
against the N. aberrans population from Coctaca (Fig. 4).
It was found that the false root nematode population from Mar del
Plata belongs to the Sugarbeet group; the commercial cultivars were
not parasitized by this population. Conclusions
- The population of N. aberrans from Coctaca belongs to
Race 2
- The Andean landrace "Azul", one genotype of
Solanum megistacrolobum and two of
Solanum acaule, presented the best behaviour against Race
2.
- The population of N. aberrans from Mar del Plata belongs to the
Sugarbeet group and did not parasitize the cultivars 'Spunta', 'Kennebec'
and 'Frital INTA'.
|
|
| |
|
 |
|
References
Castiblanco, O., Franco, F. & Montencinos, R. 1999.
Razas y gama de hospedantes en diferentes poblaciones del nematodo
Nacobbus aberrans (Thorne,1935), Thorne & Allen, 1944. Revista
Latinoamericana de la Papa 11: 85-96.
Coceen, W. A. & D´Herde, C. J. 1972. A method for the quantitative
extraction of nematodes from plant tissue. Merebeke- Belgium, State
Nematology and Entomology Research Station, 77pp.
http://nematode.unl.edu/pest27.htm Society of Nematologists.
Nacobbus aberrans. Exotic nematode plant pests of agricultural and
environmental significance to the United States.
|
|
|
