Pearl Millet (Pennisetum glaucum [L.] R. Br.) Water Use Efficiency and Productivity in Semi-Arid Conditions of Namibia

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dc.contributor.authorMoseki, Ofentse
dc.date.accessioned2025-12-11T13:28:48Z
dc.date.available2025-12-11T13:28:48Z
dc.date.issued2025-08
dc.description.abstractPearl millet (Pennisetum glaucum (L.) R. Br.) is a C4 crop that is well adapted to semi-arid climates and is a staple food in Namibia. However, declining yields due to climate variability and changes have raised concerns regarding its sustainability and its ability to drive food security. In this study, the responses of two local pearl millet cultivars, Kangara and Okashana 2, to different water regimes (100%, 75%, and 50% crop evapotranspiration [ETc]) at the Mannheim Crop Research Station, Tsumeb, Namibia, during the 2023 and 2024 cropping seasons were investigated. A split-plot factorial design was employed to assess morpho-physiological, yield, nutritional responses and water use efficiency (WUE) of pearl millet. Additionally, the projected climatic conditions were used to estimate pearl millet yield and water productivity under various climate change and planting date scenarios. Water stress significantly affected plant height, leaf number, tillering, chlorophyll content, stomatal conductance, leaf temperature, panicle traits, biomass, grain yield, and 1000-seed weight (p < 0.001). The 50% ETc regime significantly reduced the growth and yield parameters, whereas the 75% ETc regime maintained acceptable productivity, suggesting that it is an optimal irrigation strategy under water-limited conditions. Biomass yield (BY) varied between 5.54 and 1.14 tons/ha in Season 1 and between 3.81 and 1.50 tons/ha in Season 2, while grain yield (GY) ranged from 1.23 to 0.38 tons/ha in Season 1 and from 1.02 to 0.58 tons/ha in Season 2. The highest yields were observed at 100% ETc, with a decline under increasing water stress. Okashana 2 exhibited a significantly higher harvest index under 50% ETc (p = 0.003), suggesting its ability to allocate resources effectively under water stress. WUE for BY varied from 0.78 to 1.74 kg. ha/m³, whereas that of GY ranged from 0.28 to 0.47 kg. ha/m³, with strong positive correlations between GY and BY (r = 0.88, p ≤ 0.01), and between WUE-GY and GY (r = 0.80, p ≤ 0.01). The nutritional composition was minimally influenced by water stress. Although the moisture content remained unaffected in the first season, significant differences were observed in the second season (p < 0.001), with the highest levels at 75% ETc (6.63%) and the lowest at 50% ETc (2.10%). In the second season, the fat content varied significantly (p < 0.001), with the highest content at 50% ETc (4.99%) and the lowest at 100% ETc (2.11%). Several mineral elements, including acid detergent fiber, calcium, potassium, magnesium, phosphorus, and iron (Fe), were significantly affected by irrigation regimes (p < 0.05), with the highest Fe (76.61 mg/kg) recorded at 50% 2 ETc. Principal component analysis revealed distinct correlations under different water regimes, highlighting the nutritional resilience of pearl millet. To assess future climatic effects, the AquaCrop model was used under historical (1995–2014) and projected (2020–2059) climate scenarios for two planting dates (15 December and 15 January). Future projections indicate a decline in rainfall, rising temperatures, and higher reference evapotranspiration (ETo). Water productivity is projected to decline by 22-35%, with dry yields decreasing from 0.94 to 0.81 tons per hectare in December and from 1.83 to 1.21 tons per hectare in January between 2020 and 2039. The 15th of January is recommended as the planting date to maintain crop yield under future climate conditions. These findings underscore the importance of optimising irrigation and planting strategies to enhance pearl millet production and resilience under water-limited conditions. Therefore, this study recommends adopting water-saving strategies such as deficit irrigation management to ensure the sustainability and production of pearl millet, thereby promoting food security in water-scarce environments. This study contributes to the scientific understanding of how water use and pearl millet performance are affected by moisture levels. In addition, this study contributes to the development of climate-resilient cropping systems suitable for dryland agriculture in Southern Africa.
dc.identifier.citationMoseki, Ofentse. (2025). Pearl Millet (Pennisetum glaucum [L.] R. Br.) Water Use Efficiency and Productivity in Semi-Arid Conditions of Namibia [Unpublished doctoral dissertation]. Namibia University of Science and Technoogy.
dc.identifier.urihttp://hdl.handle.net/10628/1100
dc.language.isoen
dc.publisherNamibia University of Science and Technology
dc.subjectAquaCrop model
dc.subjectAgricultural water management
dc.subjectClimate change adaptation
dc.subjectPearl millet
dc.subjectSemi-arid Namibia
dc.subjectWater use efficiency
dc.subjectWater productivity
dc.titlePearl Millet (Pennisetum glaucum [L.] R. Br.) Water Use Efficiency and Productivity in Semi-Arid Conditions of Namibia
dc.typeThesis

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