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

Effect of Seed Pre-sowing Treatment on Germination of Three Acacia Species Indigenous to Botswana

Effectiveness of selected immersion-based seed pre-sowing treatments (cold water, hot water and concentrated sulphuric acid) on the germination of three Acacia species (A. tortilis, A. erioloba, and A. nigrescens) was studied between December 2012 and January 2013. For each species, four treatments (including the control) were replicated four times in a Completely Randomized Design. Percentage germination, germination mean time (GMT) and germination index (GRI) were calculated and the data were subjected to analysis of variance (ANOVA). Significant differences in germination were observed across the treatments. Concentrated sulphuric acid significantly (P < 0.01) increased the germination percentages of A. erioloba (87%) and A. nigrescens (30%) while the control, cold water and hot water treatments significantly (P < 0.01) reduced their germination percentages (5%). However, treating A. tortilis with hot water for 9 min significantly (P < 0.01) enhanced its germination percentage (30%) compared to the other treatments. As expected the control had the highest GMT, although this was not significant for A. tortilis. The GRI revealed similar trend as germination percentages across the treatments for the three Acacia species. Based on these results, we recommend concentrated sulphuric acid and hot water as suitable seed pre-treatments for enhancing the germination of the three Acacia species

Evaluating the growth response of Cassia abbreviata oliv

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Agronomic Performance of Sorghum after Panicle Removal

A field study was conducted at Botswana College of Agriculture (BCA) farm to investigate the effect of panicle removal and no panicle removal on growth, yield and yield components of grain sorghum within and across landraces. The experiment was arranged in a complete randomized block design (CRBD), three landraces, two management practices and four replications. The sorghum landraces; segaolane, korwane and mmamokotane designated (T1-T3) represent management practice 1 (panicle removed) whereas controls designated (C1-C3) represent management practice 2 (panicle not removed) were planted in an area of 63 m2. Within landraces, treated (panicle removed) plants revealed significantly (P<.05) lower plant height, number of tillers and grains per head across the landraces. Overall, a non-significant (P<.05) treatment effect was observed for total grain weight and shoot biomass. Untreated plants (panicle not removed) significantly (P<.01) increased the harvest index in segaolane whereas a non-significant treatment effect was observed for korwane and mmamokotane. Across landraces, panicle removal significantly (P<.05) enhanced mmamokotane plant height and shoot biomass whereas it significantly (P<.01) increased the number of grains per head in segaolane. Panicle removal significantly (P<.01) increased total grain, 1000 seed weight and harvest index in korwane whereas a non-significant treatment effect was observed for number of tillers across the landraces. It is concluded that panicle removal is ineffective management practice for enhancing growth, yield and yield components in sorghum landraces. &nbsp

Growth and Development Response of Kale (Brassica oleracea var. Acephala L.) Seedlings to Different Commercial Growing Media

The study was carried out at Botswana University of Agriculture and Natural Resources (BUAN) formerly Botswana College of Agriculture (BCA) under an 80% net shade house to evaluate the response of kale (Brassica oleracea var Acephala) to different commercial growing media comprising of cocopeat, hygromix and germination mix. The experiment was set up in a completely randomized design (CRD) with each treatment (medium) replicated four times. Growth parameters measured were: seedling emergence, plant height, number of leaves, leaf area and biomass (both fresh and dry masses). Plant height, leaf area, number of leaves and biomass (fresh and dry) from plants grown on hygromix and germination mix were significantly (P < .01) higher than those grown on cocopeat. The same trend was observed in relation to seedling emergence although hygromix performed better than the other growing media. The observations reported in this study suggest that the use of hygromix and germination mix enhanced production of kale seedlings compared to cocopeat with hygromix being the best. &nbsp