Seoleseng Obonya Tshwenyane

Advocacy for using indigenous plants as livestock feed is growing, especially for poultry production in developing countries that are challenged by increasing ingredient importation costs. Corchorus olitorius is an underutilized plant broadly adapted globally between 50° N & S that is used widely as a leafy vegetable crop; however, little is known about the nutritional value of C. olitorius for poultry feed. Consequently, C. olitorius leaves were collected from multiple sites in three diverse regions of Botswana in 2025 to evaluate the nutritive value of native and improved ecotypes, with each site having 3 replicates in a completely randomized design. Leaves of C. olitorius contain sufficient levels of crude protein (CP) (205–313 g kg−1), fat (17–39 g kg−1), and several essential minerals to potentially minimize the amount of supplementation necessary from imported sources, but crude fiber (CF) levels (46–128 g kg−1) would require management to prevent that interfering with digestion. Consequently, leaves of C. olitorius may be of value for burgeoning poultry industries; however, excessive Fe content of C. olitorius leaves would need to be addressed in any ration but may present an opportunity for utilization as an organic feed supplement.

Ornamental gardening has historically been, and continues to be, a primary pathway for plant introductions into southern Africa. Knowing which alien plants are being sold and used as ornamentals in the subregion is important to assess the potential for future biological invasions and conflicts between stakeholders. We compiled a list of all plant taxa on sale across eleven nurseries in Botswana (3), Namibia (2) and Zimbabwe (6) by accessing the plants in stock either on the nurseries’ websites, on social media or via stock lists shared by the nursery owners. The compilation was matched with the Global Register of Introduced and Invasive Species to identify invasive taxa. Of 1 193 species that were found to be on sale, 784 are alien to the continental Southern African Development Community (SADC) subregion, 289 have established alien populations in at least one continental SADC country, and 82 are considered invasive in at least one continental SADC country. Many of the established and invasive plants are popular trees and shrubs in the subregion and worldwide. Most of them have a wide native range usually covering more than one continent. This paper provides a quantification of invasion debt due to the ornamental sector in southern Africa and a baseline to identify priorities for risk analysis and potential regulation or control at a subregional level.

Southern Africa has a well-documented history of intentional plant introductions for ornamental purposes, but some of these plants have become widespread damaging invaders. Conflicts can arise when stakeholders’ attitudes differ towards ornamental invasive plants and their management. We examined the views of stakeholders involved in the ornamental sector and environmental management across Southern Africa in light of the strategic actions proposed by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services' thematic assessment on ‘Invasive Alien Species and their Control.’ Our analysis is based on semi-structured interviews, informal conversations, and observations with 78 environmental specialists, 30 ornamental-related industry staff, and 24 plant enthusiasts from Botswana, Namibia, Zimbabwe, South Africa, Zambia, Democratic Republic of Congo, and Eswatini. Our analysis shows that significant efforts are ongoing in Southern Africa to address biological invasions from the ornamental sector. However, they need more integration and consideration of the broader geopolitical and socio-historical context. We reflected on these needs and recommend: 1) improving cohesion and collaboration amongst stakeholders, 2) ensuring pluralism by recognising and valuing marginalised groups, 3) addressing power differences and superiority-inferiority complexes, and 4) seeking alliances with existing sub-regional groups working in the realm of nature-society interplay. We believe that our recommendations contribute toward the necessary transformative change for tackling the underlying political and economic causes of plant invasions derived from the ornamental sector in the sub-region.

Background: Ornamental gardening is one of the main historical and current pathways for plant introductions into southern Africa. A few introduced ornamental plants have become invasive, sometimes triggering conflicts between stakeholders. Knowing which alien plants are being sold and used as ornamentals in the sub-region is important to assess the potential for future biological invasions and conflicts between stakeholders. Objectives: This paper identifies and characterises the ornamental plants on sale in three southern African countries, and compared these to lists of plants considered invasive in the area of the continental Southern African Development Community (SADC). Methods: We compiled all plant taxa sold across eleven nurseries in Botswana (3), Namibia (2) and Zimbabwe (6) by accessing the plants in stock either on the nurseries’ website, on social media, and via stock lists shared by the nursery owners. The compilation was matched with the Global Register of Introduced and Invasive Species to identify invasive taxa. This sub-group was characterised by growth form and biogeographical origin. Results: 1,193 species were found to be sold, of which 784 are alien to the continental SADC sub-region, 289 have established alien populations in at least one continental SADC country, and 82 are considered invasive in at least one continental SADC country. Many of the established and invasive plants are popular trees and shrubs in the sub-region and worldwide. Most of them have a wide native range usually covering more than one continent. Conclusions: This paper provides a quantification of the invasion debt due to the ornamental sector in southern Africa, and a baseline to identify priorities for risk analysis and potential regulation or control at a sub-regional level. Approaches to reduce the sale of invasive species, however, need to be considered carefully, since their current popularity across the sub-region could make them a source of conflict between the ornamental horticulture sector and those tasked with managing biological invasions.

Humans and ornamental plants have a long relationship that could explain why ornamental gardening has been one of the main reasons for intentionally introducing and spreading plants worldwide. In Southern Africa, a significant part of the alien flora was introduced for ornamental purposes. Some species have become invasive, with ecological and socio‐economic impacts that can create conflicts between stakeholders, depending on their relationships with the species. This paper unpacks how the ornamental industry in Southern Africa operates as well as people's preferences for ornamental plants and practices to highlight links between the industry and plant invasions and to help address potential conflicts. Drawing on empirical data primarily collected in 2022/23 in Botswana, Namibia and Zimbabwe (and other Southern African countries), our results show that Southern Africa's ornamental industry is highly influenced by the global industry, especially South Africa. The sector provides ‘formal’ and ‘informal’ jobs to people in urban areas, especially middle‐aged women from ethnic majorities. The sector's operation and gardening practices show expressions of the typical cultural hybridity of postcolonial states where hegemonic and subaltern practices coexist and mix. Alien plants and foreign styles often symbolise higher social status, but controversially, socially privileged groups are publicly leading shifts towards more geographically contextualised practices and native plants. We conclude by arguing that recognising the influences that historical processes have on the sector's operation and its links with alien plants is essential for a more ethically sound and fair stakeholder engagement in preventing and managing plant invasions from the ornamental industry in Southern Africa.

ISHS International Symposium on Wild Flowers and Native Ornamental Plants The floriculture potential of some indigenous plants of Botswana

This study was done to elucidate the effects of nitrogen (N) and phosphorus (P) on fruit quality of watermelon. The experimental design was a split-plot laid down in randomized complete blocks with three replications. The treatments were 0, 50, 100, 150 and 200 kg N/ha (main-plots) and 0, 25, 50 and 75 kg P/ha (sub-plots). There were no interactions between N and P treatments on all the dependent variables analyzed. Application of 50, 100, 150 and 200 kg N/ha to watermelon plants significantly (P < .0001) increased fruit quality (lycopene content, vitamin C, titratable acidity and fruit rind thickness) compared to fruit from control plants. However, P application had no significant (P = .05) effects on fruit lycopene content, vitamin C content, titratable acidity, soluble solids content and fruit rind thickness compared to fruit from control plants. In conclusion to optimize watermelon fruit quality, application of 150 kg N/ha and 50 kg P/ha to watermelon plants was recommended.

ISHS VI International Postharvest Symposium EFFECT OF HARVESTING TIME ON THE RESPIRATION RATE AND VASE LIFE OF THREE CUT ROSE CULTIVARS 'GOLDEN GATE', 'DUETT' AND 'CREAM PROPHYTA'