Translocation of 14CO2 and 14C- deoxyglucose in bracken (Pteridium esculentum Forst. f. Cockayne): Implications for herbicide efficacy

Abstract

The translocation of photoassimilates and foliarly applied chemicals in glasshouse-grown Australian bracken (Pteridium esculentum Forst. f. Cockayne) was investigated using two radiotracer techniques: (1) pulse labeling of 14CO2 in enclosed fronds and (2) application of 14C-deoxyglucose using a microsyringe in fully expanded frond. In the first experiment, the translocation and distribution of 14CO 2 was determined in the different parts of 4-mo-old bracken, where either the young or old frond was pulse-labeled with 14CO 2. In the second experiment, the effects of pretreatment application of plant hormones (kinetin or ethephon) in the translocation and distribution of 14C-deoxyglucose and metsulfuron-methyl applied concurrently on 1 1/2-yr-old bracken plants with extensive rhizome system was investigated. Fully expanded fronds function as source while rhizome apices, frond buds and unexpended fronds are the main sinks. A relatively low proportion of fixed 14C was exported from fed fronds, and the rhizome system was the dominant sink for exported 14C. The two radiotracer experiments differed in the amounts of radiolabel exported to the different parts of bracken due to differences in plant age and size of bracken plants used. Both experiments confirmed that the direction of translocation follows the photoassimilate pathway to actively growing meristems, e.g., rhizome buds and apices and rapidly expanding fronds. The application of plant hormones enhanced the translocation of 14C-deoxyglucose in the rhizome system, presumably a result of altered source: sink ratios due to stimulation of metabolic activity in the subterranean part of the weed. The similarities and differences between the two radiotracer experiments were discussed and potential implications for increasing the efficacy of the chemical control of bracken were noted.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

417-426

Document Type

Article

Subject

14 C-deoxyglucose, 14 CO 2, Australian bracken, Ethephon, Kinetin, Metsulfuron-methyl, Translocation

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