Correlation of population of plant nematodes and soil temperature in Mangifera indica

Abstract

Most of the studies have been conducted on the vertical distribution of migratory ecto and semi endoparasites than with any other groups of nematodes. From the various experiments, it has been found that the population density of nematodes was greatest in top 30 cm of soil and generally declined to 30-60 cm depths. It has been also demonstrated that nematodes distribution often is correlated with root distribution. In some cases (Rhodopholus similes) it has been observed that the nematode population increased with the deeper strata of soil. Temperature is one of the important edaphic factors that acts as a stimulus of vertical distribution. We have seen that nematodes do have different levels of temperature preference and that there is undoubtedly active migration under some circumstances. It is often stated that nematodes move downward in winter “to get away from cold” but assuming that there is considerable vertical migration at least more than we know about how much due to temperature changes and how much to other factors. But now a days it is possible to find out the precise role of one specific factor out of various edaphic factors through using various statistical tools like multivariate analyses and ANOVA. Ecological study of plant parasitic nematodes plays an important role in minimizing the infestation of almost all the parasitic forms of Phyto nematodes. The nematode population size depends on action and reaction of edaphic factors including the host plant itself. Analysis of relationship between variation in soil parameters and the irregular pattern should lead to an improved understanding of how these organisms interact with the soil environment. In the present work the population density of major parasitic Phyto nematodes was studied in respect of soil edaphic factors. Soil samples were collected from three vertical depths (0.0-20.0 cm; 20.01- 40.0 cm 40.01- 60.0 cm) and three horizontal distances (30 cm; 60 cm; and 90 cm) from the stem of the host i. e., mango (Mangifera indica). Functional linear relationships confirmed inverse relationship with soil temperature with that of the total nemic population. Few positive thermo -response were observed at 40.01-60.0 cm vertical depth (P<0.20) at 30 cm distance.