Effects of Temperature on,Resistance in Phaseolus vulgaris Genotypes and on Development of Meloidogyne Species


  • G. M. Sydenham
  • R. McSorley
  • R. A. Dunn


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 24ºC and 24ºC, 24ºC and 28ºC, 28ºC and 24ºC, and 28ºC and 28ºC. 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 28ºC 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 30ºC and 32ºC. Key words: common bean, host plant resistance, Meloidogyne arenaria, Meloidogyne incognita, nematode development, Phaseolus vulgaris, resistance mechanisms, root-knot nematode, temperature.