Effects of Temperature on Resistance in Phaseolus vulgaris Genotypes and on Development of Meloidogyne Species.
Phaseolus vulgaris lines with heat-stable resistance to Meloidogyne spp. may be needed to manage root-knot nematodes in tropical regions. Resistance expression before and during the process of nematode penetration and development in resistant genotypes were studied at pre- and postinoculation temperatures of 24 degrees C and 24 degrees C, 24 degrees C and 28 degrees C, 28 degrees C and 24 degrees C, and 28 degrees C and 28 degrees C. Resistance was effective at all temperature regimes examined, with fewer nematodes in roots of a resistant line compared with a susceptible line. Preinoculation temperature did not modify resistance expression to later infections by root-knot nematodes. However, postinoculation temperatures affected development of Meloidogyne spp. in both the resistant and susceptible bean lines tested. The more rapid development of nematodes to adults at the higher postinoculation temperature of 28 degrees C in both bean lines suggests direct temperature effects on nematode development instead of on resistance expression of either of two gene systems. Also, resistance was stable at 30 degrees C and 32 degrees C.
Sydenham
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GM
McSorley
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Dunn
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RA