Effect of Meloidogyne graminicola on Growth and Nematode Multiplication in Rice

The cultivation of rice is seriously affected by rice root knot nematode in nursery, transplanted crop as well as in direct seeded rice. Studies were conducted in pot house, Department of Plant Pathology to assess the damaging effects of Meloidogyne graminicola in two different rice varieties viz. PR 126 and Pusa Basmati 1121 at five initial inoculum levels on growth variables and nematode population. Sterilized soil was inoculated with second stage juveniles (J2) of M. graminicola to give 1000, 2000, 3000 and 4000 J2/g soil along with control where no inoculation of nematode was done. Amongst nematode variables, there was increase in soil nematode population and root galling index (RGI) with increase in inoculum levels. All inoculum levels caused significant reduction in growth variables of rice. With each increase in inoculum levels from 1000–4000 juveniles, nematode multiplication was increased. The extent of reduction in plant height, root length, and dry biomass was more pronounced in Pusa Basmati 1121 than in PR 126 which indicates varietal differences in susceptibility. The highest RGI and nematode population were recorded at 4000 J2/g soil which suggests that higher initial inoculums densities lead to greater nematode reproduction and damage. The study highlights the potential yield loss risk posed by M. graminicola even at low initial populations. This highlights the importance of selecting tolerant varieties and implementing effective nematode management strategies for sustainable rice production..