<p>The physiological, morphological, and host reaction responses of eighteen green gram cultivars were evaluated to determine their relative susceptibility to the root-knot nematode infection. Inoculation with 2000 J₂ of <i>Meloidogyne incognita</i>/kg soil incited extensive galling on the roots and induced stunting of plant growth, leaf yellowing, reduced flowering and podding, and lower grain yield losses. The root galling among the cultivars, varied greatly with 32—152 galls/root system, being highest in cv. K-851 and lowest in cv. ML-5. The <i>M. incognita</i> infection significantly reduced the plant growth (22—28%), yield (15—24%), and nodulation (13—21%), with greatest reductions observed in highly susceptible five cultivars K-851, IPM 02—14, SML-668, Pant Mung 4, and Pant Mung 5, whereas moderately susceptible cultivar (cv. ML-5) exhibited 10—12%, 9—10%, and 7—14% reductions, respectively. Nematode development, reproduction, and population varied among the cultivars, being highest on cv. K-851 and lowest on cv. ML-5. The nematode infection significantly influenced the major physiological parameters decreasing the photosynthesis rate (14—28%) but increasing the stomatal conductance and transpiration rate (18—25%). The leaf pigments viz., chlorophylls and carotenoids were significantly decreased (10—36%). The physiological alterations were recorded to be most pronounced in the highly susceptible cv. K-851, whereas lesser degree of variations were observed in the moderately susceptible cultivar like ML-5. In the present study, the all green gram cultivars whether highly susceptible, susceptible or moderately susceptible exhibited significant yield declines (10—24%), although highest reduction occurred in the cv. K-851 that exhibited greatest number of galls.</p>