Phenotypic variation in fruit, seed and seedling traits of nine Uapaca kirkiana provenancesfound in Malawi

摘要

Uapaca kirkiana is one of the priority indigenous fruit tree species for domestication in southern Africa. Natural populations of U. kirkiana are declining due to deforestation, forest fragmentation and wildfires. Knowledge of genetic variation is prerequisite for development of conservation strategies. A provenance evaluation study was conducted at Bunda College of Agriculture in Lilongwe, central Malawi to determine the variability in fruit, seed and seedling characteristics of nine populations found in the southern, central and northern regions of Malawi. Results showed significant differences (P<= 0.05) between provenances in fruit weight, seed weight, seed length and seed width. The central Malawi provenances of Dzalanyama and Chimaliro had theheaviest mean weight of fruits of 23.9g and 23.8 g respectively, the lightest fruits (14.6g) were found in Namoni Katengeza provenance. There were no significant differences (P <= 0.05) in number of seeds per fruit within and between provenances. The provenances differed significantly in cumulative germination percentage, ranging from 26% for Tsamba provenance in southern Malawi to 87% for Dzalanyama provenance in central Malawi. There was a consistent regional variation in stem collar diameter and height growth with central Malawi (Dzalanyama and Chimaliro) and northern Malawi provenances having taller seedlings ranging from 5.2 to 9.0 cm, with the exception of Namoni Katengeza provenance in central Malawi. The root collar diameters were significantly higher for Dzalanyama and Chimaliro (2.5 to 3.9 cm) than southern Malawi provenances whose seedling collar diameter averaged 2.3 centimetres. The nursery provenance trial has shown existence of considerable variation in seed germination, fruit and seedtraits in U. kirkiana. Seed and seedling growth traits may prove to be important criteria for selection of provenances for domestication to provide farmers with sustained fruit production for consumption and economic benefits.