Germination Response of Albizia lebbeck (L.) Benth Seed to Different Scarification Treatments in Botswana

Evaluation of different pre-sowing treatments on germination of A. lebbeck seeds was conducted in
the laboratory at Botswana University of Agriculture and Natural Resources (BUAN) from January to
February 2018. The experiment was laid out in a completely randomized design (CRD) with five
treatments as follows; mechanical scarification, boiling water, hot water, concentrated sulphuric acid
(98.8%) and control (untreated seeds). Sulphuric acid had four different levels of exposure time (15,
30, 45 and 60 minutes), whereas boiling water had three levels of exposure time (1, 3 and 5 minutes).
Each treatment had four replications. Germination percentages (GP), mean germination time (MGT)
and germination index (GI) were calculated and the data were subjected to analysis of variance
(ANOVA). Significant (p<0.01) differences in germination parameters were observed across the
treatments. Concentrated sulphuric (60 minutes) had superior absolute numbers than the rest
including the control, recording 82% compared to 8% for control. However, no statistical differences
were observed across the three main treatments; all sulphuric acid, boiling water (1 minute) and
mechanical scarification. The control revealed the longest MGT which was significantly (p<0.01)
longer than the rest. As would be expected, pre-sowing treatments which outperformed others in
terms of germination percentages recorded, significantly (p<0.01) increased the GI as compared to
control. Based on these findings, mechanical scarification, boiling (1 minute) and hot water treatments
are recommended as suitable seed pre-sowing treatments for enhancing the germination of A.
lebbeck seeds because the methods are cheap and easy to perform. Although concentrated sulphuric
acid yielded the best rest results the method is not recommended because of its high cost and the
danger it poses to workers.