Meloidogyne Species (Root Knot Nematodes) Associated with Different Climatic Conditions of the Sorghum bicolor Production Sites in Telangana, India

Abstract

Although crop damage due to nematodes in Telangana, Sorghum bicolor crops has been suspected and sampled occasionally and no study on Meloidogyne species (root-knot nematodes) associated with different climatic conditions of the soil has yet to be reported. In the present study, we report the Meloidogyne species associated with different climatic conditions (seasonal variations) and edaphic factors like soil moisture, soil pH, organic matter, sand, silt, clay, and soil types of the Sorghum bicolor crop production sites, which could be useful to get more knowledge and develop appropriate management strategies. A total of 60 rhizosphere soil samples along with roots were collected from 60 fields of 4 villages to provide comprehensive coverage of the S. bicolor production sites in four agro-climatic districts of Telangana. An aliquot from each of the 60 composite soil samples was processed for estimation of the soil conditions like moisture, organic content, pH, sand, silt, and clay. Subsequently, nematodes were isolated by Baermann funnel and Cobb's method, identified by root dissection, and verified using a microscope. Out of 60 soil samples, 21.2% of Meloidogyne-like species were observed at 5.0-7.5% of soil moisture, 27.3% at 17.5-20% of soil organic matter, 30.3% at pH between 7.0 and 7.5, 51.5% at 15-20% of silt, 36.4% at 20 to 25% of the rhizosphere clay and 45.5% of Meloidogyne-like species at 50-55% of rhizosphere sand. The distributions of other root-knot nematode species between different soil types were statistically significant (p-value = 0.039). The distributions of Meloidogyne-like species between different soils were statistically insignificant (p-value = 0.212). However, the infested roots were often carved in the shape of a hook, horseshoe, or a complete spiral without excessive proliferation of secondary roots which was common in Meloidogyne-like species. The results of this study can be used as an advisory to the farmers who intend to take only a particular variety of crops in their field but were unaware of the damage that was happening underground due to biotic and abiotic factors.