Evaluation of Cucumis sativus var. hardwickii Cultigens for Resistance to Root-knot Nematodes

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Cucurbit Genetics Cooperative Report 20:19-20 (article 10) 1997

S. Alan Walters and Todd C. Wehner
Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609

Resistance to root-knot nematode has been identified in Cucumis sativus var. hardwickii cultigen LJ 90403 (2). Currently, that is the only cultigen identified that is cross-compatible with Cucumis sativus and also has multiple nematode resistance. A selection of LJ 90403, NC-42, was released for use in breeding because it had significantly higher resistance than check cultivars like ‘Sumter’ and ‘Wisconsin SMR 18’ (4). We were interested to find whether other cultigens of C. sativus var. hardwickii cultigens in our collection for resistance to root-knot nematode species Meloidogyne javanica, and M. arenaria races 1 and 2.

Three C. sativus var. hardwickii cultigens (LJ 90403, PI 215589, and PI 462379) were evaluated for resistance to three root-knot nematodes (M javanica, and M. arenaria races 1 and 2). The experiment was set up as a completely randomized design with three replications. Plants were grown using the split-root technique (3). Plants were transplanted with approximately one-third of the root system of each plant in each of three 10-cm plastic pots. Each pot was inoculated with 5000 eggs of one root-knot nematode (M javanica, and M. arenaria races 1 and 2). Ten weeks after inoculation, roots were rated for percentage galling from 0 % to 100 % (1). A cultigen was considered susceptible if it had a gall index above 25 %, and highly resistant if it had a gall index rating below 15 %.

As found in previous studies, LJ 90430 was resistant to all three nematodes (Table 1). The other two C. sativus var. hardwickii cultigens (PI 215589 and 462379) were resistant to M. arenaria race 1. However, LJ 90430 (and the NC-42 selection) is still the only known cultigen of Cucumis sativus with resistance to M javanica.

This study indicated that there are multiple sources of resistance to root-knot rnematodes. Additional cultigens of C. sativus var. hardwickii need to be collected and evaluated to determine whether even higher levels of resistance exist.

Table 1. Root-knot nematode resistance of three Cucumis sativus var. hardwickii cultigens and three check cultigensz.

Gall index rating for 3 root knot nematodes

Cultigen

M. Arenaria race 1

M. Arenaria race 2

M. javanica

hardwickii cultigens
LJ 90430 11 8 8
PI 215589 45 14 46
PI 462379 9 6 60
Check cultigens
NC-42 (LJ 90430) 11 5 6
Sumter 58 72 55
Wis. SMR 18 65 73 63
Mean 33 30 40
LSD (5%) 11 12 14
CV (%) 21 26 22

z Data are means of 3 replications of plants tested in split-spots.

Literature Cited

  1. Baker, K.R., J.L. Townshend, G.W. Bird, I.J. Thomason and D.W. Dickson. 1986. Determining nematode population responses to control agents. In: Methods for Developing Pesticides for Control of Plant Pathogens, (K.D. Hickey, ed.). St. Paul, APS Press. p. 283-287.
  2. Walters, S.A., T.C. Wehner and K.R. Barker. 1993. Root-knot nematode resistance in cucumber and horned cucumber. HortScience 28:151-154.
  3. Walters, S.A., T.C. Wehner and K.R. Barker. 1995. Split-root technique for multiple nematode resistance in cucumber. Cucurbit Genetics Coop. Rpt. 18:29-30.
  4. Walters, S.A., T.C. Wehner and K.R. Barker. 1996. NC-42 and NC-43: Root- knot nematode resistant cucumber germplasm. HortScience 31:1246-1247.