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Nerium oleander indirect leaf photosynthesis and light harvesting reductions after clipping injury or Spodoptera eridania herbivory: High sensitivity to injury
- Variable indirect photosynthetic rate (Pn) responses occur on injured leaves after insect herbivory. It is important to understand factors that influence indirect Pn reductions after injury. The current study examines the relationship between gas exchange and chlorophyll a fluorescence parameters with injury intensity (% single leaf tissue removal) from clipping or Spodoptera eridania Stoll (Noctuidae) herbivory on Nerium oleander L. (Apocynaceae). Two experiments showed intercellular [CO2] increases but Pn and stomatal conductance reductions with increasing injury intensity, suggesting non-stomatal Pn limitation. Also, Pn recovery was incomplete at 3d post-injury. This is the first report of a negative exponential Pn impairment function with leaf injury intensity to suggest high N. oleander leaf sensitivity to indirect Pn impairment. Negative linear functions occurred between most other gas exchange and chlorophyll a fluorescence parameters with injury intensity. The degree of light harvesting impairment increased with injury intensity via lower (1) photochemical efficiency indicated lower energy transfer efficiency from reaction centers to PSII, (2) photochemical quenching indicated reaction center closure, and (3) electron transport rates indicated less energy traveling through PSII. Future studies can examine additional mechanisms (mesophyll conductance, carbon fixation, and cardenolide induction) to cause N. oleander indirect leaf Pn reductions after injury.
Kevin J. Delaney
Nerium oleander , Spodoptera eridania , carbon dioxide , chlorophyll , electron transfer , energy efficiency , fluorescence , gas exchange , herbivores , leaves , mechanical damage , photosystem II , stomatal conductance
- Plant science 2012 April v.185-186
- Elsevier Ireland Ltd
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.