Effects of aphid disoperation on photosynthetic performance and agronomic traits of different sorghum varieties

The current study used photosynthetic indexes to investigate the mechanism of aphid resistance in two sorghum varieties with different aphid tolerance. (Pn, Tr, Gs, Ci), chlorophyll fluorescence parameters (Fo, Fm, Fv/Fm, Y (II), qP, NPQ) as well as some agronomic traits (chlorophyll content, plant height, fresh weight, dry weight, root length, root number) that treated at different aphid densities (0, 10, 20 and 40 aphids/plant) and at different infestation times (4d, 8d, 12d and 16d). The results showed that, as aphid density and infestation time increased, the agronomic traits, the most photosynthetic parameters and the most chlorophyll fluorescence parameters showed a larger decrease in sensitive sorghum variety, whereas a minor decrease was observed correspondingly in the resistant variety. Comprehensive analysis indicated that five indicators, including Pn, Tr, Gs, Y(II), qP and chlorophyll content, were easily disturbed under large density of aphid and long infestation time. Among which three indicators, including chlorophyll content, Pn and Y (II), played a crucial role in promoting crop yield and thus could be considered as the key indicators in studying the aphid resistance in sorghum. (author)