Propagule Type Affects Growth and Fruiting of Uapaca kirkiana, a Priority Indigenous Fruit Tree of Southern Africa

Abstract

One of the limitations of Uapaca kirkiana on-farm cultivation is the long juvenile phase to reach a stable fruiting stage. Marcots and grafts have been identified as feasible and reliable propagation methods for precocious fruiting, but the effects of different propagule types on tree growth and fruit yield have not been evaluated. There is limited knowledge on development and growth forms for trees derived from different propagules. Grafts and marcots were compared with saplings to assess the variability in 1) field growth and fruiting of U. kirkiana; and 2) dry matter allocation pattern and tree development models among trees derived from different propagules. Tree development models were used to examine differences among trees from different propagules. The results show that number of branches and fruit load significantly differed between vegetative propagules and saplings, whereas tree height, root collar diameter, crown spread, and fruit size and weight were similar 8 years after establishment. The results suggest differences in intraspecific scaling relationships between height and diameter among propagule sources. Saplings showed a significantly better fit (r2 = 0.891; P < 0.0001) to the scaling relationship than grafts (r2 = 0.724; P = 0.002) and marcots (r2 = 0.533; P = 0.018). After 3 years, marcots and grafts started producing fruits. Fruit load was greatest in marcots despite some fruit abortions; thus, marcots had greater fruit yield, early growth, and development and better dry matter allocation