Submitted to: International Plant Protection Congress
Publication Type: Proceedings
Publication Acceptance Date: March 28, 1995
Publication Date: N/A
Technical Abstract: Plant entries previously shown as resistant or susceptible to Diuraphis noxia were used to evaluate effect of aphid feeding on leaf chlorophyll content and in vivo chlorophyll fluorescence induction kinetics. D. noxia feeding for 96 h caused significant reductions in Chlorophyll a, Chlorophyll b, and total chlorophyll content in susceptible wheat and barley. Total chlorophyll content and constituent chlorophyll a and b levels were not significantly affected by D. noxia in resistant wheat or barley, or in resistant or susceptible triticale. D. noxia infestation resulted in significant alterations of the primary fluorescence induction transients. When compared with noninfested control plants, infested susceptible wheat and barley showed significantly increased non-variable fluorescence (Fo) and decreased maximal fluorescence (Fm) and variable fluorescence (Fv). In contrast, values for these parameters did not differ significantly among infested and noninfested controls of resistant plants. When compared with control plants, photochemical efficiency of photosystem II (Fv/Fm) and half rise time from Fo-Fm (t1/2) were reduced significantly in infested susceptible entries but remained relatively unchanged for infested resistant cultivars. No significant differences between infested and noninfested plants were observed in measured chlorophyll fluorescence parameters for either resistant or susceptible triticale, implying different resistance mechanism(s) to D. noxia. Results suggest that D. noxia damage goes beyond simple removal of photosynthates from the plant. The substantial decrease in Fv/Fm after infestation of susceptible wheat and barley indicated a significant decrease in capacity and efficiency of the primary photochemistry of photosystem II.