AbstractThe infection with Meloidogyne incognita induced physiological variations, biochemical imbalances, and decline in the nitrogen fixation, leading to severe yield loss in green gram cv. SML-668, that varied with the inoculum levels (100-3000 J2/kg soil). Increasing inoculum levels caused a progressive rise in the root galling, with maximum disease severity and nematode development. The egg mass production, fecundity (eggs/egg mass), juveniles population (in soil), preadult females, adult females (in side root tissue), reproduction factor, and multiplication factor of M. incognita were recorded highest at 3000 J2/plant, and the lowest at 100 J2/plant over the control. A significant decline in the photosynthesis rate (6-32%), and an increase in transpiration rate (8-28%) and stomatal conductance (8-26%) occurred in the plants inoculated with 500-3000 nematode juveniles/plant. The leaf chlorophylls (28-56%), carotenoids (24-52%), and seed protein (24-44%) of the nematode infected plants decreased significantly, with the greatest reductions at 1500-3000 J2/plant. Phenolic and salicylic acid concentrations increased by 3-30% and 2-18% at 100-1000 J2/plant, but decreased by 10-28% and 6-15% at 1500-3000 J2/plant compared to 1000 J2/plant. The greatest reductions in the plant growth indices (41-74%), yield (32-43%), functional nodules (26%), nodule weight (44%), and leghemoglobin content (32%) occurred at 3000 J2/plant, whereas the least decline at 100 J2/plant compared to the control. The non-functional nodules, however, increased with an increase in the inoculum level. The soil population of the juveniles peaked at 3000 J2/plant.
Ahmad et al. (Wed,) studied this question.