Aspects of ¹⁴C-Sucrose Translocation Profiles in Hibiscus esculentus L. (Okra)

Abstract

The translocation patterns of ¹⁴C from ¹⁴C-sucrose applied to vegetative okra plants were investigated in relation to duration, leaf position, nitrogen and phosphorus nutrition, and water stress.

When the lowermost, most mature leaf 1 was fed with ¹⁴C-sucrose, distribution was initially at 6 h uniform to the leaves, stem and root; but at 48h, the root accumulated about 60% of the total exported ¹⁴C. The uppermost, expanding leaf 4 distributed a substantial proportion of its minimally exported ¹⁴C initially downward to the root, but progressively upward to the shoot apex. The application of high levels of N and P led to enhanced movement of ¹⁴C out of the fed leaf. While high levels of N stimulated distribution to leaves, high levels of P were inhibitory. A water stress pulse lasting 3 days had no significant effect on the patterns of ¹⁴C translocation but minimally influenced that of ³²P.

It is concluded that in the vegetative okra plant, (a) leaves do not export ¹⁴C assimilates principally in terms of proximity to a given organ, but in response to demands by specific sinks which vary with time; (b) high levels of N and P enhance the movement of ¹⁴C out of the fed leaf, but the effects of N on distribution patterns are generally opposite to those of P; and (c) water stress which does not result in significantly inhibited growth also does not adversely affect ¹⁴C translocation.

This work was supported by National Research Council of Canada and University of Ibadan Sentae research grants.