Choshali et al. Page 54 RESEARCH PAPER OPEN ACCESS The effects of soil organic matter content and soil texture on the population number of Pratylenchus loosi, in tea plantation of Iran A. Hosseinikhah Choshali 1* , A. Seraji 2 , S. Rezaee 1 , A. Shirinfekr 2 , S.N. Mirghasemi 3 1 Department of Plant Pathology, College of Agriculture and Natural Resources, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Plant Protection & Soil Science Departments, Iranian Tea Research Institute, Lahijan, Guilan, Iran 3 Plant Protection Department Deylaman, Guilan, Lahijan, Iran Article published on February 22, 2015 Key words: Camellia sinensis, Root lesion nematodes, Soil characteristics and Regression analyses. Abstract Tea, Camellia sinensis (L.) Kuntze, is an edible and evergreen plant which has numerous medicinal and calmative characteristic. Tea root lesion nematodes, Pratylenchus loosi, is one of the most important pests in Iran, which causes loss in quantity and quality of tea. 183 soil and root samples were taken randomly from tea plantations in Iran. The highest mean population of P. loosi in soils and roots was observed in soils with organic matter less than 2 percent. The results of regression analyses showed that there is no significant correlation between soil organic matter content with neither the population number of nematodes in one g of feeder roots nor the population density in 100 g of soil. Three types of soil texture classes were observed such as loam, sandy loam and sandy clay loam as if the highest percentage of infestation was observed in sandy loam soil. The results of regression analysis showed that there was no significant correlation between sand, silt and clay percent with mean population of nematode in sandy loam, sandy clay loam and loam soils. Total results showed that tea root lesion nematode in light texture soils are more active and had greater population numbers. * Corresponding Author: A. Hosseinikhah Choshali  ahosseinikhah@yahoo.com International Journal of Agronomy and Agricultural Research (IJAAR) ISSN: 2223-7054 (Print) 2225-3610 (Online) http://www.innspub.net Vol. 6, No. 2, p. 54-61, 2015