Studies focusing on some reproductive traits that foster the invasion of Gomphocarpus fruiticosus, Argemone mexicana, Sesbania bispinosa, and Verbesina encelioides were carried out in Gaborone, Botswana. The specific objectives of these studies were to: (i) determine density of stems; (ii) determine the number of inflorescences/flowers and fruits produced per plant; (iii) determine the number of seeds per fruit, plant, and hectare; (iv) determine the 1000-seed weight and single-seed mass; (v) test different pre-sowing treatments on the germination of seeds; and (vi) assess the density of soil seed banks of the species. Results on density of the four study species as well as numbers of inflorescences, flowers, fruits, and seeds plant−1, m−2, and ha−1 are presented. Among the study species, the numbers of seeds kg−1 ranged between 129 870 (S. bispinosa) and 458 715 (A. mexicana), while the numbers of seeds ha−1 ranged between 62 330 000 (G. fruiticosus) and 8 890 070 000 (V. encelioides). Fresh seeds of the study species failed to germinate even when they were subjected to different pre-sowing seed treatments, except S. bispinosa, which responded well to the scarification pre-sowing treatments, germinating up to 98%. These results indicate that the seeds possess deep dormancy, a strategy that spreads germination of the study species over appropriate time and space. The study species also accumulated large numbers of viable seeds in the litter and topsoil layers, ranging between 3 400 000 (A. mexicana) and 14 380 000 (S. bispinosa) seeds ha−1, suggesting that the study species accumulate persistent seed reserves in the soil, which will guarantee recruitment of seedlings in the event of natural and/or anthropogenic disturbances. These results indicate that the study species are well equipped with a number of reproductive traits that foster their rapid invasion of new areas, making them powerful noxious invaders, as can be evidenced from their rampant invasion in the study site. Therefore, any effort in the management, control, or elimination of these species that does not take these reproductive traits into account is bound to fail. Recommendations that could help in addressing the invasion of the study species in Botswana are forwarded.

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.

The seeds of Senegalia galpinii (Burtt Davy) Seigler and Ebinger and Vachellia robusta (Burch.)Kyalangalilwa and Boatwright have hard coatimposed dormancy that prevents water and air from entering the seeds, which is essential for the germination process.The specific objectives of this study were to determine the number of seeds per pod for the study species; determine the size and weight of seeds; and test the effects of scarification pre-sowing treatments on the speed, uniformity and total percent germination of seeds.Seeds of both species were subjected to 10 different pre-sowing seed treatments: the control, mechanical scarification, soaking in concentrated sulphuric acid (for 15, 30, 45 and 60 minutes), immersion in boiling water (for 1, 3 and 5 minutes), and soaking in boiling water (and cooling down for 24 hours).The germination data were examined using an analysis of variance and Tukey's honestly significant difference test to separate significantly different treatment means.The results showed that the mean number of seeds per pod was 7 ± 0.2 and 10 ± 0.03 for S. galpinii and V. robusta, respectively.For S. galpinii, the mean length, width and breadth of seeds were 12 ± 0.2, 10.4 ± 0.1 and 2.7 ± 0.03 mm, respectively.For V. robusta, the mean length, width and breadth of the seeds were 10 ± 0.1, 6.1 ± 0.1 and 4.2 ± 0.1, respectively.The mean thousand-seed weights were 275 ± 3 and 183.6 ± 6 g for S. galpinii and V. robusta, respectively.The results indicated that seeds treated with mechanical, sulphuric acid and boiling water scarification had significantly higher mean germination percentages than the controls for S. galpinii, whereas for V. robusta, mechanical scarification, exposure to sulphuric acid and immersion in boiling water and then cooling down for 24 hours yielded a better total percent germination than the controls.The highest mean germination percentages for S. galpinii (92-100%) were observed for seeds

Field experiment was conducted at Botswana University of Agriculture and Natural Resources (formerly Botswana College of Agriculture) from March-July 2016 to evaluate effects of intercropping on the performance of sorghum (segaolane) and cowpeas (black eye) in Botswana. The design of the experiment used was a complete randomized block design (CRBD) with five treatments including two controls (sole crops) each replicated three times. Growth parameters (plant height, number of leaves and canopy spread) and grain/seed weights were determined on five pre-determined plants from each plot and the collected data was subjected to analysis of variance (ANOVA). Generally, the number of leaves, plant height and canopy spread for both cowpeas and sorghum were non-significant (p˃0.05) across the treatments for the first six weeks after planting except for significant number of leaves for sorghum. The following weeks cowpeas and sorghum intercrop showed significant (p<0.05) differences in number of leaves, plant height, canopy spread with 50%/50% cowpeas and sorghum revealing superior absolute numbers most of the time. However, sorghum exhibited reduced growth in plant height and canopy spread across treatments which was non-significant (p˃0.05) until termination. Weights of cowpeas in 50%/50% and 25%/75% intercrop of cowpea and sorghum were significantly (p<0.05) higher whereas, 75%/25% intercrop of sorghum and cowpeas had significantly (p<0.05) higher weights for sorghum. Based on the findings, 50%/50% intercrop of cowpeas and sorghum, and intercrop of 75%/25% sorghum and cowpeas are recommended as the most desirable cropping systems. * Corresponding Author: Gabatshele Mbona Legwaila  glegwaila@buan.ac.bw International Journal of Biosciences | IJB | ISSN: 2220-6655 (Print), 2222-5234 (Online) http://www.innspub.net Vol. 14, No. 1, p. 444-453, 2019

Growth and development response of parsley (Petroselinum crispum) to four application rates of organic fertilizers (treatments) was investigated in a field experiment at the Botswana University of Agriculture and Natural Resources (formerly Botswana College of Agriculture) from November 2014 to March 2015. The experiment was laid out in a complete randomised block design (RCBD) with each of the four treatments; 0, 5, 7.5 and 10 kg m-2 replicated three times. Data on growth and development parameters viz., plant height, number of leaves, leaf area and plant canopy (spread) was recorded at weekly intervals whereas, stem diameter (thickness), and shoots fresh and dry weights were recorded at the termination of the experiment. In general, significant statistical differences (P<0.05) were revealed for plant height, leaf area, number of leaves, stem thickness, canopy diameter and shoots fresh and dry weights. Application rates of organic fertilizers of 10 kg m-2 significantly enhanced the performance of the growth and development parameters of parsley with highest application rate revealing numerical superiority. Based on the findings, highest application rate of organic fertilizer is recommended to small scale farmers because its constituents are readily available and are in abundance locally.

This study was carried out at Botswana University of Agriculture and Natural Resources (BUAN) formerly Botswana College of Agriculture (BCA) under an 80% net shade to investigate the effect of growing media comprising cocopeat, hygromix and germination mix on growth and development of sweet pepper (Capsicum annum L.) seedlings. The experiment was set up in a completely randomized design (CRD) with each treatment (growing medium) replicated four times. Growth parameters measured were; seedling emergence, plant height, leaf number and area, and seedling biomasses (both fresh and dry). Seedling emergence from hygromix and germination mix was significantly (P<0.05) higher than cocopeat in the first 15 days whereas a non-significant (P˃0.05) treatment response was observed from day 16 to 20 across treatments. Plant height, leaf number and area, and seedling biomasses were significantly (P<0.01) higher in hygromix and germination mix as compared to cocopeat with hygromix revealing superior performance than germination mix. Hygromix and germination mix can be used to propagate sweet pepper because they enhanced seedling emergence, growth and development. Seedlings emerged in cocopeat, but the seedlings remained stunted suggesting that the medium needs further investigation on how it can sustain seedling growth and development.

A germination experiment of Vachellia rehmanniana seeds was conducted in the laboratory of the Department of Crop Science and Production, Botswana University of Agriculture and Natural Resources from November to December 2016. Mature Vachellia rehmanniana seeds were collected from healthy erect trees at Butale Village, Botswana to investigate the effect of different pre-sowing treatment methods on seed 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 had three different levels of time exposure (1, 3 and 5 min) whereas, concentrated sulphuric acid had four different levels of time exposure (15, 30, 45 and 60 min). The results revealed that seed germination percentage, germination mean time and germination index were significantly (P < 0.01) affected by pre-treatment methods. The highest significant cumulative germination percentages were recorded in seeds subjected to boiling water for 3 and 5 min, sulphuric acid for 45 and 60 min, and mechanical scarification. Based on the findings mechanical scarification and boiling water techniques are recommended for use in nurseries and by farmers because sulphuric acid is expensive and need to be handled by trained individuals. It is recommended that future research should target increasing the exposure time over five and 60 minutes for boiling water and sulphuric acid treatments, respectively for this species to increase the cumulative germination percentage.

A survey was conducted at Botswana University of Agriculture and natural Resources at Sebele content farm to determine the intensity and level of mistletoe infestation in tree species. The intensity and the total number of trees per tree species infected by the parasitic weed were determined. Acacia eriobola, Acacia mellifera, Terminalia sericea, Ziziphus mucronata, Schinus molle, Acacia tortilis, Acacia erubesens and Acacia flekii hosted the highest number of mistletoe. Results revealed significant variation in level of mistletoe infestation between tree species. A 100% infestation was recorded in some tree species such as Acacia eriobola and Ziziphus mucronata. Severely infested indigenous tree species were dying, whereas most of the exotic tree species were either not infested or have very little number of mistletoe on them. The variation observed could be due to the fact that indigenous species the frequently visited by dispensers looking for food and shelter than exotic species. In addition, there is a possibility that the mistletoe species co-evolved with the indigenous tree species and the vector may be well established on the host tree species than on exotic species.

Commercial growth media were evaluated for their effect on tomato (Lycopersicon esculentum L.) seedling emergence, growth and development in 80% net shade house at Botswana University of Agriculture and Natural Resources from March-April 2015. Three locally available commercial growth media (germination mix, cocopeat and hygromix) were used. A completely randomized design (CRD) with four repetitions was used. Tomato seeds were sown on 200 cells styrofoam seedling trays to evaluate seedling emergence. Thereafter, the following growth and development parameter were measured; leaf number and area, plant height, fresh and dry masses. Data was subjected to analysis of variance (ANOVA). Results revealed no significant differences (p>0.05) in seedling emergence among the three growing media for the entire study period. However, hygromix gave superior absolute numbers compared to other two growth media. Hygromix also gave significantly (p<0.01) larger leaves and taller seedlings than germination mix and cocopeat whereas, no significant difference was observed on shoot fresh and dry masses. Growing media had no significant influence on seedling emergence rate although hygromix sown seeds still emerged relatively faster than the other media. Growers must pay attention to details when selecting the medium to use. Therefore, hygromix and to some extent germination mix are recommended as the most desirable growing media for raising tomato seedlings. * Corresponding Author: Thembinkosi Mathowa  tmathowa@bca.bw International Journal of Agronomy and Agricultural Research (IJAAR) ISSN: 2223-7054 (Print) 2225-3610 (Online) http://www.innspub.net Vol. 9, No. 1, p. 83-91, 2016 International Journal of Agronomy and Agricultural Research (IJAAR) ISSN: 2223-7054 (Print) 2225-3610 (Online) http://www.innspub.net Vol. 5, No. 1, p. 14-22, 2014

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.

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.

Seedlings growth and development of tomato (Lycopersicon esculentum L.) as influenced by various container size was evaluated at Botswana University of Agriculture and Natural Resources (formerly Botswana College of Agriculture) from March-April 2015. Propagation containers with different cell sizes (volumes of 18.5 cm3, 65 cm3 and 170 cm3 being treatments) were used. The experiment was laid as a completely randomized design (CRD) with four repetitions. Tomato seedlings were grown in a net shade house of 80%. The following growth and development parameters were recorded; plant height, leaf number and area, and shoot fresh and dry weights. Data was subjected to analysis of variance (ANOVA). Plant height showed a non-significant (p˃0.05) difference in response to treatments in the first three weeks followed by a highly significant (p<0.01) response in the fourth week. The latter response was revealed for leaf number and area, and shoot fresh and dry weights except for a significant (p<0.05) response in week two for leaf number. Generally bigger (170 cm3) cells significantly enhanced the performance of the seedlings as compared to smaller (18.5 cm3) cells. As a result the bigger cells are recommended as the most desirable containers for quality seedlings.

A field experiment was established at the Botswana University of Agriculture and Natural Resources to evaluate the effects of organic fertilizer on yield and yield attributes of tomato from October 2014 to March 2015. The experiment was laid out in a randomised complete block design (RCBD) with four treatments being varying levels of organic fertilizer; 0 kg m, 5 kg m, 7.5 kg m and 10 kg m each replicated three times. The growth attributes measured were plant height, stem thickness, canopy diameter, number of leaves, fruits and fruit weight. Organic fertilizer application rates of 7.5 and 10 kg m showed significantly (P = .05) taller plants from weeks 4 to 6 compared to other treatments. A highly significant difference in plant canopy was observed across the four application rates from weeks 1 to 5. Canopy spread was overall higher in the 10 kg m application rate across all the weeks. A highly significant treatment effect was observed on leaf number with plants in the 10 kg m application rate exhibiting the highest number of leaves. Stem thickness showed significance differences across treatments with the 10 kg m application rate having thicker stems. A highly Original Research Article Mojeremane et al.; AJEA, 12(1): 1-10, 2016; Article no.AJEA.24630 2 significant treatment effect was observed on number of harvested fruits with the 7.5 kg m application rate showing higher yields between the first and fourth harvest and 10 kg m application rate from fifth to sixth harvest. Organic fertilizer had a significant effect on fruit weight from first to third harvest with the 10 kg m application rates having the heaviest tomato fruits. The 10 kg m application rate outperformed the lower rates for most measured parameters. The organic fertilizer is recommended to small-scale vegetable growers because it is affordable and abundant in Botswana.

Okra is a newly cultivated crop in Botswana. Plant population has been identified as one of the factors that contribute to poor plant development and lower yields. The effects of various intra-row spacing on yield and yield components of okra variety; Clemson Spineless was evaluated at Botswana College of Agriculture in Sebele. The treatments consisted of five intra-row spacings of 30, 45, 60, 75 and 90 cm for treatments 1-5 respectively, each of the treatment was replicated three times in a Randomized Complete Block Design (RCBD). Yield and yield components were determined on five pre-determined plants from each plot and the raw data was subjected to analysis of variance (ANOVA). Generally, a significant treatment effect was revealed for plant height with narrower plant spacing of 30 cm significantly increasing the plant height. Wider plant spacing of 90 cm significantly increased the plant weight, number of branches and leaves. A nonsignificant treatment effect was observed for stem diameter, fruit length and diameter, number of flowers and fruits. Based on the results wider intra-row spacing of 90 cm is recommended for okra production.

The effect of irrigation regime on some growth characteristics and water use efficiency (WUE) of the native common Bermuda grass was evaluated during dry season from January to May 2011 at the Horticultural Section, Faculty of Agriculture, Khon Kaen University, Thailand. Rhizomes of native common Bermuda grass were planted in 4x1 m concrete blocks with open bottoms. Four daily irrigation levels were applied as follows; 50, 75, 100 (control) and 125% of evaporation pan (E-pan) or 0.50, 0.75, 1.00 and 1.25 E-pan, respectively. The randomized complete block design with four replications was used. The results showed that 0.50 E-pan irrigation had the lowest relative water content, fresh clip and dry clip biomasses, whereas it had the highest dry root biomass at soil profile 0-10 cm. Moreover, the clip/root ratio at soil profile 0-10 cm and total soil profiles 0-30 cm exposed the lowest value in 0.50 E-pan irrigation. In addition, the relationship between dry clip biomass, irrigation amount (IR) and ratio IR/E-pan (IE) were polynomial which had the highest biomass at 0.75 Epan irrigation, while the relationship between dry root biomass, IR and ratio IE showed a decreasing tendency with an increase in irrigation amount. The WUE was found to be highest at 0.75 E-pan irrigation level.

The study was carried out at Botswana College of Agriculture (BCA) garden to evaluate the response of Corchorus olitorius grown in four different growing media as follows; clay, sandy, commercial compost and loam soil being the treatments 1-4, respectively. A completely randomized design (CRD) with each treatment replicated four times was used. Productivity parameters and yield components measured were as follows; plant height, canopy spread, leaf area, stem diameter, number of leaves, branches and pods, both fresh leaf and dry masses, both fresh plant (stem + branches) and dry masses, both fresh root and dry masses, and both fresh pod and dry masses. Biomasses were also calculated for leaf, plant, roots and pods. C. olitorious yielded significant (p<0.01) results under clay, sandy and to some extent loam soils with respect to plant height, canopy spread, leaf area, stem diameter, number of leaves, branches and pods, both fresh leaf and dry masses, both fresh plant and dry masses, both fresh root and dry masses, both fresh pod and dry masses, plant biomass and pod biomass. A non-significant treatment effect was observed for root and leaf biomasses. Based on the results it is concluded that the use of clay and sandy soils enhanced production in jute mallow.