Partitioning, storage and remobilization of 14C assimilated by Themeda triandra Forssk.

Abstract

The second youngest fully-expanded leaf on the main tiller of vegetative Themeda triandra plants was exposed to 14CO2. Thereafter, quantitative analysis of partitioning, storage and remobilization after defoliation of 14C-labelled assimilate was conducted in serially-harvested plants over a 27-day period. In undefoliated plants, 50% of assimilated 14C was ultimately lost through respiration, while that remaining in the plant reached its final destination within two days of assimilation. A small, but significant, portion of assimilated 14C was invested into long-term storage in roots and stem bases. These reserves were remobilized after defoliation, and a portion of the remobilized 14C was incorporated into new growth. Partially-defoliated plants regrew more rapidly than totally-defoliated plants, but they both made equal demands on 14C reserves. Reserve depletion took place from both roots and stem bases.

Keywords: 14c; assimilation; defoliation; growth; labile carbon reserves; leaves; partitioning; plant physiology; regrowth; reserves; respiration; roots; stem; storage; structural carbon; themeda triandra; tiller