Application and Use of Presowing Treatment Methods to Improve Germination of Vachellia karroo (Hayne) Banfi & Galasso

Abstract

A germination experiment of <em>Vachellia karroo</em> seeds was conducted at the Botswana University of Agriculture and Natural Resources, Department of Crop and Soil Sciences laboratory, from September to October 2018. Seeds were collected along the Segoditshane River in Gaborone to investigate the effect of different pre-sowing treatment methods on their germination. The experiment was laid out in a completely randomized design (CRD) with five treatments (control, mechanical scarification, boiling water, hot water and concentrated sulphuric acid (98.8%). Boiling water (30, 60, 180 and 300 seconds) and concentrated sulphuric acid (15, 30, 45 and 60 minutes) had four levels of exposure time. The highest significant (p &lt; 0.01) cumulative germination percentages were recorded in seeds subjected to sulphuric acid for 45 and 60 minutes, mechanical scarification (shortest germination mean time of 2.0<strong>-</strong>2.3) and boiling water at 30 and 60 seconds (moderate germination mean time of 5<strong>-</strong>5.9) whereas, the control treatment had the least cumulative germination percentage of 2%. As expected, the same trend was revealed for germination index. The seeds possess seed coat imposed dormancy, which requires sowing treatments. The best treatments for releasing dormancy in <em>V. karroo</em> were sulphuric acid and mechanical scarification and because of the risks associated with the use of sulphuric acid, the researchers recommend mechanical scarification as the suitable treatment method in tree nurseries.