Localized defoliation stress and the movement of ¹⁴C- photoassimilates between tillers of Carex bigelowii

The ¹⁴C-translocation from a labelled tiller to a daughter tiller in control plants was fastest during the first day after labelling, when most of the ¹⁴C was translocated. When daughter tillers were defoliated, amount of ¹⁴C translocated into them from labelled parent tillers was increased 6-fold and the rate of translocation was still high 4 d after labelling. Greatest amounts of ¹⁴C were recovered in green leaves and rhizomes of daughter tillers, but highest concentration was found in roots. In control plants, the amount of ¹⁴C-subsidy to young tillers was inversely related to their size, larger tillers tending to be more photosynthetically independent, but when the young tillers were defoliated, the ¹⁴C-subsidy increased to all size classes. When young tillers were defoliated repeatedly, at 10-12 d intervals their parent tillers subsidized them with increased amounts of ¹⁴C after a 1st and 2nd defoliation, but not after a 3rd defoliation. When the parent tillers were repeatedly defoliated, increased ¹⁴C-supplies from daughter tillers were cut off after the 1st defoliation. -from Authors