Correlative Growth in Young Terminalia superba in a Controlled Environment: Effect of the Leaves on Internode Elongation

Young Terminalia superba plants were cultivated in a controlledenvironment at the Phytotron. Effects of the excision of a youngleaf at definite elongation stages and at two given levels ofthe main axis were studied on the elongation of internodes inthese plants. Effects of the leaf did not seem to depend onits nodal position on the main axis but predominantly occurredon the immediate surrounding internodes. The excision of a youngleaf enhanced the growth rate of the internode located belowit and markedly decreased the elongation of the internode aboveit but slightly affected internode growth duration. This excisionenhanced the final length of the internode located below theleaf and decreased the final length of the internode locatedabove the removed leaf. Significant linear regressions werefound between the length of the excised leaf and the internodefinal lengths. Microscopic examination of epidermal cells ofcontrol and disrupted internodes revealed that the decreasedelongation after leaf excision could be attributed to reductionof cell divisions. The increased elongation after leaf excisioncould be attributed both to slight increase in the length ofcells (significant negative correlation was found with the lengthof the removed leaf) and to increase of cell divisions. Terminalia superba, leaf excision, cell division, internode elongation, correlative growth