Morphological and Biochemical Host Response of Fifteen Indian Rice Cultivars to Rice Root-Knot Nematode, Meloidogyne graminicola

The relative susceptibility and resistance reactions of fifteen rice cultivars were evaluated against rice root-knot nematode, Meloidogyne graminicola under pot conditions. The variation in the synthesis of total phenol (TP) and salicylic acid (SA) as influenced by host reaction and subsequently their impact on the disease etiology was assessed. The cultivars inoculated with 1000 second stage juveniles (J₂s) of M. graminicola expressed varied responses. The cv. Shanthi expressed resistance reaction, whereas the cvs. Pusa Basmati-6 and Pusa Sugandh-5 were found highly susceptible to the nematode. The greatest increase in the leaf contents of SA (9–15%) and TP (10–13%) was recorded in the cv. Shanthi, which also exhibited lowest root-knot index (0.8 at 0–10 scale) and decrease in the rice yield. The TP and SA contents of leaves increased up to 15 days of planting, and thereafter, decreased gradually. Increase in the TP and SA was negatively correlated with the root-knot index. Based on the morphological and biochemical host reaction, the relative susceptibility of the 15 cultivars was in the order; Pusa Basmati-6 > Pusa Sugandh-5 > Pusa Sugandh-4 > R-Dhan > Surya > Sharbati > Sadabhar > Virendra > Anjali > Swarna > CR-314 > PA6444 > JKRH401 > Vivekdhan 62 > Shanthi. The study revealed that the cvs. Vivekdhan 62 and Shanthi may be exploited for commercial cultivation of rice in the host zone of rice root-knot nematode, while the cultivation of cvs. Pusa Basmati-6 and Pusa Sugandh-5 should be avoided.