New Zealand Journal of Agricultural Research abstracts
Resistance in Trifolium repens and T. semipilosum to
Meloidogyne trifoliophila (Nematoda: Tylenchida) is temperature
sensitive
C. F. Mercer
AgResearch Limited
Private Bag 11 008
Palmerston North, New Zealand
Abstract The clover root-knot nematode parasitises
white clover throughout New Zealand’s improved pastures. White clover
with partial resistance to this endoparasite has been developed in a
recurrent selection programme. Temperatures in the root zone of white
clover exceed 25°C each summer and our objective was to determine
if resistance was stable at these temperatures. In Experiment 1, clonal
copies of resistant and susceptible white clover and Kenya white clover
genotypes were planted in inoculated soil and maintained at 25, 28.5 or
32°C. In Experiment 2, resistant and susceptible seed lines of
white clover were challenged as seedlings. In Experiment 1, the mean of
the root-knot nematode gall counts on the resistant white clover
genotypes was about half that on the susceptible genotypes (P
< 0.01) at 25°C, but was not different at the two higher
temperatures; similarly on Kenya white clover, resistance was only
expressed at 25°C. In Experiment 2, seedlings reflected the pattern
shown with copies of genotypes. The breakdown of resistance to the
clover root-knot nematode at these temperatures exacerbates the
constraints already placed on clover productivity by the summer
drought.
Keywords breeding; Meloidogyne
trifoliophila; nematodes; pasture; resistance; selection; Trifolium
repens; Trifolium semipilosum
A05017; Received 27 April 2005; accepted 13 June 2005; Online
publication date 4 August 2005
New Zealand Journal of Agricultural Research, 2005, Vol. 48:
339–343
0028–8233/05/4803–0339 © The Royal Society of New Zealand 2005
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