Distribution of cereal cyst nematode, Heterodera filipjevi, in wheat fields of Isfahan province based on interpolation and relationship of climatic factors with its population densities

This study was conducted to identify cereal cyst nematodes (CCNs), distribution and disease incidence, population density and preparing map of distribution based on interpolation using geographic information system (GIS), as well as determination of relationship between climatic factors with population density of dominant species. Totally 280 soil and root samples were randomly collected from 140 wheat fields of Isfahan province during 2012-2014. The soil samples were processed for cyst extraction and number of cysts, second stage juveniles (J2) and eggs inside each sample were counted. Species was identified based on morphological and morphometric features and molecular characters. Analysis was performed by Arc GIS software using interpolation technique for determination of raster maps of population density of J2, eggs and direction of disease progression. After preparing the raster maps, direction and the correlation of J2 and eggs populations with some climatic factors and altitude determined by GIS using Pearson's correlation coefficient. Heterodera filipjevi was the only species of cereal cyst nematodes found in Isfahan province, and 56.4% of soil samples were contained H. filipjevi with an average population of 6.02 eggs and J2/g of soil. Based on interpolation of population density, Ardestan, Natanz, Kashan, Aran va Bidgol, Mobarekeh, Naein and Isfahan districts had the most mean population density of H. filipjevi, respectively. Population density of the nematodeshowed direct correlation with the long term mean of temperature and inverse correlation with the long term mean of precipitation, relative humidity percent and altitude.