MIGRATION AND REPRODUCTION OF MELOIDOGYNE INCOGNITA IN TWO SOIL TEXTURES

Abstract

The purpose of this study was to evaluate the migration of second-stage juveniles (J2) of Meloidogyne incognita at different distances from the root system of tomato cultivated by direct sowing or transplanted into either clay or sand, and to determine the effect of soil type on nematode infectivity and reproduction. Cylinders of 10 and 20 cm diameter, enclosed in a 0.36-mm diameter mesh and filled with clay soil or sand were placed in
the center of 1-m2 wooden boxes. Second-stage juveniles were placed inside the cylinder and tomato seedlings cv. ‘Kada’ were sown or transplanted externally surrounding the cylinder. The control consisted of two tomato plants cultivated in the center of the box without cylinder with clay or sand and infested with J2. The motility and neutral lipid content from J2 used before and those sampled 20 days after inoculation from the cylinders were estimated. Infectivity and reproduction of M. incognitawere evaluated 30 days after inoculation. More J2 were recovered from the cylinders containing sand than clay soil, but the number of J2 was not affected by the type of planting (sowed or transplanted). The motility and the neutral lipid content of J2 extracted from the 20-cm cylinders filled with sand containing transplanted seedlings decreased drastically when compared to the control. Regarding the content of neutral lipids from J2 recovered from the cylinders, there was a significant interaction between soil texture and type of planting for neutral lipid content, and between the type of planting and the distance from inoculum deposition. Independent of the type of planting, lower nematode infectivity and reproduction were observed in J2 in sand than in clay soil. An interaction also was seen between soil texture and the type of planting for infectivity and reproduction. This is the first report of using a three dimensional environment to monitor the distance M. incognita J2 migrate to a host root system, as influenced by soil texture, mediated by lipid loss and the type of planting on infectivity and reproduction of M. incognita.