Influence of different temperatures on resistance of tomato plants to Meloidogyne incognita

Abstract

Seedlings of resistant tomato cultivars VFN 8 were grown at 28, 31, 34 and 37 DC and infested with Meloidogyne incognita. Resistance of tomato seedlings fell progressively as temperature rose. The total number of nematodes increased as temperature increased; most galling occurred at 34"C and 50% of the larvae that had invaded the roots completed their development. Necrosis of root tissue was observed only at 28"C and one week after infestation; at 34 DC gall sections showed multinucleate cell formation, associated with necrotic cells. The loss of resistance in heat treated plants of tomato influenced the behaviour of the peroxidases. At 28 uC infested plants increased enzyme activity, in all cellular components examined, at 34"C healthy heat treated plants showed increase of peroxidases, but no changes occurred after nematode infestation.