Meloidogyne graminicola's Effect on Growth Performance of Rice under Low Population Density

Meloidogyne graminicola is a destructive soil-borne pathogen that causes rice yield losses (Oryza sativa L.) in tropical and subtropical areas. This study investigated the effect of M. graminicola population densities on plant height, heading, and the photosynthetic parameters of rice in a greenhouse. Two-week-old rice plants were inoculated with different M. graminicola densities (250, 500, 750, 1000, 1500, and 2000 J2s/plant) and observations were recorded at 30, 60, and 90 days after inoculation (DAI). Reductions in growth and photosynthetic parameters caused by M. graminicola densities were calculated in relation to a control (non-inoculated rice). Results revealed that M. graminicola infection with low population densities (0-500 J2s/plant) did not influence the rice plant height during 30-60 DAI, but significantly lowered the plant height, panicle growth rate, and panicle length of rice at 90 DAI. The chlorophyll content of rice inoculated with 500-2000 J2s was significantly lower than that of the control. Furthermore, M. graminicola infection with 500 J2s/plant significantly lowered the transpiration rate and net photosynthetic rate by 21.21% and 21.81%, respectively, compared with the control (p < 0.05). M. graminicola with a low population density significantly reduced the net photosynthetic rate of rice, which affected organic matter accumulation, resulting in growth retardation and lower yields (p < 0.05).

Automated summary

Meloidogyne graminicola population densities have a significant effect on the height and photosynthetic parameters of rice plants. Low population densities do not affect the height of rice plants during the initial 30-60 days, but significantly decrease the growth and photosynthetic parameters at 90 days. Higher population densities lead to reduced chlorophyll content and decreased photosynthetic rate in rice plants.