No abstract

The rhizoid of Chara hispida L. made a small contribution to the uptake of inorganic phosphate under laboratory conditions. At 1 mmol m−3 phosphate the rhizoid contributed about 4% to the uptake of the whole plant over 4 h. Under these conditions about half of the phosphate taken up by the rhizoid was translocated into the shoot. The rates of uptake and translocation increased with increasing external phosphate concentrations. When the shoot was in darkness, 32P‐translocation from the rhizoid was less than half of that found when the shoot was illuminated. When the rhizoid medium was anaerobic the translocation rate was lower than the rate in aerobic conditions and illumination of the shoot had no effect on the uptake or translocation of phosphate. Translocated 32P accumulated in the apical growing regions of the plant. This was first noted in the secondary apices nearest to the rhizoids.

No abstract

Rates of uptake of '^C-labelled inorganic carbon wet-e tncasut-cd for whole Chara hispida plants, detached parts of the shoot and isolated (^split-chamber technique) apices, latet-al bt-anchlets atid rhizoid-node cotnplexes.The rates of inot-ganic carbon uptake by the rhizoid node cotnplex exptessed per gratn ftesh weight whole plant were tht-ee to four ot-dcrs of tnagnitude less than the uptake for the whole plant. Up to 70% of the carbon taken up by the rhizoid node cotnplex was translocated to the shoot. After 12 h exposute to '"^C-labellcd inot-ganic carbon the concentration of '"^C was greater in apices than in uppertnost or ccnttal internodal cells and in all latetal branchlets, t-cgat-dless of whether label was supplied to the whole plant or isolated thizoid-nodc complexes, Measutement of inot-ganic carbon uptake by detached internodal cells and detached and isolated apices and lateral btanchlcts showed that latct-al branchlets had the gt-catest rates of inorganic carbon uptake, Duting 12 h exposure to '•*C, isolated latet-al branchlets tt-anslocated to the attached shoot 55% of the labelled carbon taken up; for isolated apices this value was only 13%, It is concluded that it is highly unlikely that the rhizoid of Chara hispida could acquiie a significant fractioti of the whole plant lequitetnent for inotganic carbon and that apices ate sink regions for photosynthate while lateral btanchlets ate source tegions.