The Effects ofSeptoria nodorumandXanthomonas translucensf. sp.undulosaon Photosynthesis and Transpiration of Wheat Flag Leaves

Abstract

In photosynthetic studies, either X. translucens or Pseudomonas cepacia was applied in combination with S. nodorum to flag leaves of wheat at the 50% heading stage. Apparent photosynthetic rate (APR) and transpiration rate of flag leaves did not differ statistically in the X. translucens + S. nodorum treatment compared with S. nodorum alone. An interaction may have occurred when plants were incubated at 24.degree. C; at lower incubation temperatures, combined inoculation had no effect compared with inoculation with either organism alone. Flag leaves had higher APR and transpiration rates when P. cepacia was applied at the same time as S. nodorum. S. nodorum may affect photosynthesis by reducing stomatal aperture and, concomitantly, transpiration. P. cepacia apparently is an effective antagonist when applied at the same time as S. nodorum.