Maliata Athon Wanga

The objective of this study was to examine the effects of kraal abandonment dration on fodder crop performance and soil fertility in semi-arid Namibia. Five crops—Cenchrus ciliaris, Medicago sativa...

Pearl millet (Pennisetum glaucum (L.) R. BR.) is a C4 plant adapted to semi-arid climates and is one of the primary staple foods in Sub-Saharan Africa, including in Namibia. The decline in yields associated with water scarcity over the years has been a national concern in the country. An experimental field trial was conducted at the Mannheim Crop Research Station, Namibia, during the 2023 and 2024 cropping seasons to investigate the response of two local pearl millet cultivars (Kangara and Okashana 2) to different water regimes (100%, 75%, and 50% crop evapotranspiration [ETc]) according to morpho-physiological and yield parameters. Pearl millet was planted in a split-plot factorial design with four rows per plot under the three water regimes, and the genotypes were planted in subplots. The results revealed that the water regime had a significant effect on plant height, number of leaves, tillers, chlorophyll content, stomatal conductance, leaf temperature, stem thickness, number of productive tillers, panicle diameter, panicle length, dry panicle weight, biomass, grain weight, and 1000-seed weight of the two pearl millet cultivars (p < 0.001). At 50% ETc, the water regime significantly reduced the growth and yield parameters compared with the 75% ETc and 100% ETc water regimes, highlighting the significance of water in plant development and growth. The findings highlighted that both cultivars responded similarly to water stress. Seventy-five percent of ETc is recommended to be applied in pearl millet systems in semi-arid conditions. This research has significant implications for the planning and producing of pearl millet under water-limited environments under changing climatic conditions.

Sorghum (Sorghum bicolor [L.] Moench) is a valuable crop in the dry regions of the world, including Namibia. Due to the intensity and recurrence of drought and heat stress in the traditional sorghum growing areas, there is a need to breed and deploy new generation farmer-preferred and climate-smart cultivars to serve the diverse value chains. Therefore, the objectives of this study were to assess the present state of sorghum production in northern Namibia and document farmers’ perceived production constraints and trait preferences in new varieties to guide drought-tolerance breeding. A survey was conducted using a participatory rural appraisal in the following six selected sorghum-growing constituencies in Namibia: Kapako and Mpungu (Kavango West Region), Eenhana and Endola (Ohangwena Region), and Katima Mulilo Rural and Kongola (Zambezi Region). Data were collected using a structured questionnaire involving 198 farmers in 14 sampled villages across the regions. Results revealed variable trends in sorghum production among respondent farmers when disaggregated by gender, age, number of households, education level, cropping systems, types of varieties grown, and perceived production constraints. An equal proportion of male and female respondent farmers cultivate sorghum, suggesting the value of the crop to both genders in Namibia. Most respondent farmers (63.6%) were in productive age groups of <40 years old. In the study areas, low-yielding landrace varieties, namely Ekoko, Okambete, Makonga, Kamburo, Nkutji, Katoma, Fuba, Dommy, Kawumbe, and Okatombo, were widely cultivated, and most of the farmers did not use chemical fertilizers to cultivate sorghum. Farmers’ perceived sorghum production constraints in the study areas included recurrent drought, declining soil fertility, insect pest damage, high cost of production inputs, unavailability of improved seed, lack of alternative improved varieties with farmers’ preferred traits, lack of organic manure, limited access to market and limited extension service. The key farmers’ preferred traits in a new sorghum variety included high grain yield, early maturity, and tolerance to drought, in the field and storage insect pests. The study recommends genetic improvement and new variety deployment of sorghum with the described farmers-preferred traits to increase the sustainable production of the crop in Namibia.

Breeding new and high performing cultivars with market‐preferred traits take more than 10 years in the absence of an integrated pre‐breeding programme. During the early phases of breeding a significant amount of time, space and resources are invested in the selection and genetic advancement stages after initial crosses are performed with parental genotypes. Speed breeding has the potential to reduce the time required for cultivar development, release and commercialization. The objective of this review was to present the key opportunities and challenges of speed breeding to guide pre‐breeding and breeding programmes. Key challenges of speed breeding include: (a) access to suitable facilities, (c) staff trained in the protocol, (b) adopting major changes to breeding programme design and operations, and (d) the need for long‐term funding. The current review highlights the potential advantages of speed breeding for the successful development and release of pure line cultivars in self‐pollinated crops in ~5 years versus 8 to 10 years when using traditional methods.

Success in inducing genetic variation through mutagenic agents is dependent on the source and dose of application. The objective of this study was to determine the optimum doses of a single and combined use of gamma radiation and ethylmethane sulfonate (EMS) for effective mutation breeding in sorghum. The study involved two concurrent experiments as follows: in experiment I, the seeds of four sorghum genotypes (‘Parbhani Moti’, ‘Parbhani Shakti’, ‘ICSV 15013′, and ‘Macia’) were treated using gamma radiation (0, 300, 400, 500 and 600 Gy), EMS (0, 0.5 and 1.0%), and gamma radiation followed by EMS (0 and 300 Gy and 0.1% EMS; 400 Gy and 0.05% EMS). In experiment II, the seeds of two genotypes (‘Macia’ and ‘Red sorghum’) were treated with seven doses of gamma radiation only (0, 100, 200, 300, 400, 500 and 600 Gy). Overall, the combined applied doses of gamma radiation and EMS are not recommended due to poor seedling emergence and seedling survival rate below LD₅₀. The best dosage of gamma radiation for genotypes Red sorghum, Parbhani Moti, Macia, ICSV 15013 and Parbhani Shakti ranged between 392 and 419 Gy, 311 and 354 Gy, 256 and 355 Gy, 273 and 304 Gy, and 266 and 297 Gy, respectively. The EMS optimum dosage ranges for genotypes Parbhani Shakti, ICSV 15013, Parbhani Moti and Macia were between 0.41% and 0.60%, 0.48% and 0.58%, 0.46% and 0.51%, and 0.36% and 0.45%, respectively. The above dose rates are useful to induce genetic variation in the tested sorghum genotypes for greater mutation events in sorghum breeding programs.