Pattern and control of distribution of ¹⁴C-assimilates in reproductive plants of Lolium multiflorum Lam. var. Westerwoldicum

Abstract

The distribution of ¹⁴C-assimilates was examined in reproductive plants of Lolium multiflorum Lam. var. Westerwoldicum (cv. Tama) from which all emerged tillers had been removed, leaving the main tiller with two expanding leaves, one of them the flag leaf, and two expanded leaves. Export of ¹⁴C from the lower expanded leaf was mainly to the tiller in its axil, the stem internode below its node and the roots, whereas the upper expanded leaf supplied predominantly the expanding leaves, the ear, stem internodes, roots and the tiller bud in the axil of the lower leaf. Defoliation and root-pruning showed that expanding leaves were able to compete successfully for assimilates, probably through the production of substances capable of mobilizing supply. Local application of 1-naphthaleneacetic acid (NAA), gibberellic acid (GA₃) and 6-benzylaminopurine (BAP) to small tiller buds showed that GA₃ and BAP promoted bud growth and ¹⁴C accumulation, but that addition of NAA reduced these effects.