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

A germination experiment of Vachellia karroo 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 < 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 2.0-2.3) and boiling water at 30 and 60 seconds (moderate germination mean time of 5-5.9) 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 V. karroo 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.Keywords: Seed dormancy, Germination mean time, Germination index, Pre-sowing treatment, Germination percentage, Germination rate, Tree nursery

Assessing evidence on the agronomic and environmental impacts of turfgrass irrigation management

In recent years, rising competition for water coupled with new environmental regulations has exerted pressure on water allocations for turfgrass irrigation. In this article, we reviewed published scientific and industry evidence on the agronomic and environmental impacts of turfgrass irrigation using a robust systematic review methodology. Our focus was on the links between (i) irrigation management (amount and frequency), (ii) agronomic responses to irrigation (turf quality, growth rates and rooting) and (iii) environmental impacts (nitrogen leaching). Based on an initial screening of 653 studies and data extracted from 83 papers, our results show that in most cases, under moderate levels of deficit irrigation (50%–60% of actual evapotranspiration), turf quality can be maintained at an acceptable level but with lower water consumption compared to irrigating back to field capacity. Irrigation beyond field capacity was found to increase the risk of nutrient leaching. However, evidence also showed that the concentration and total loss of math formula in leachate were influenced more by nitrogen (N) rates, soil characteristics, turfgrass species and turfgrass growth rates than by irrigation practices. Our analyses suggest that turfgrass irrigation should be scheduled to apply water at moderate levels of deficit irrigation, sufficient to maintain turfgrass quality but limited to promote a deep and extensive rooting system. The findings provide new insights and valuable evidence for both scientists and practitioners involved in turfgrass research and management

Evaluating the growth response of Cassia abbreviata oliv

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