Early decapitation on African plum control-pollinated seedlings and consequences on subsequent growth in Cameroon

Abstract A decapitation test was used to assess control-pollinated seedlings' growth in Dacryodes edulis. Thirty nine weeks after sowing, pot-grown seedlings belonging to 13 control-pollinated progenies from 4 provenances were decapitated by removal the shoot apex or the uppermost node, leaving shoots of uniform height of 40 cm. The stem size (height and diameter) were measured and the number of leaves counted weekly for a period of 39 weeks after sowing (WAS) in the nursery. Then, the length and number of lateral shoots (twigs) subsequently formed were measured during a period of 2 to 8 weeks after decapitation (WAD) in a net house to determine the branching frequency. Previous to decapitation, seedling height did not showed significant variation (P>0.05) in all crosses combined, 39 WAS. However, seedling collar diameter and number of leaves showed significant variation (p<0.05). Eight weeks after decapitation, only the number of vigorous twigs showed significant variation (p<0.05) in all crosses combined. The number of weeks after decapitation was the strong predictor of the shoot elongation. According to the conceptual basis of the decapitation test interpretation, the “Sprouting and the Dominance Phases” were not observed in the present study. In fact, D. edulis showed a synchronal shoot growth after decapitation. This habit could be used as a predictive test according to the relationship between branching habit and harvest index.