Browsing by Author "Nakanwagi, Mildred Julian"

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    Accuracy of using leaf blade length and leaf blade width measurements to calculate the leaf area of Solanum aethiopicum Shum group
    (Heliyon, 2018) Nakanwagi, Mildred Julian; Sseremba, Godfrey; Nahamya, Pamela Kabod; Masanza, Michael; Balyejusa Kizito, Elizabeth
    Leaf area is an important parameter when determining growth response under normal as well as stressed environments. No attempt had been made to come up with an affordable but accurate alternative of measuring leaf size in research neglected leafy vegetable crops. Other techniques such as use of leaf area meters are either destructive, expensive or both. A study was conducted to determine leaf area in like-shaped leaves of research neglected crop plants, taking case of S. aethiopicum Shum group (SAS) germplasm. Data was collected on 552 individual plants (including pure lines and hybrids) at eight weeks after planting where a third fully open leaf from top of each plant was considered. Leaf blade length (LBL) and leaf blade width (LBW) were linearly measured while leaf area (LA) was measured using a leaf area meter. This was followed by correlation and regression analysis of LA with LBL, LBW, and LBL þ LBW. Correlation coefficients at p < 0.001 ranged between 0.84 and 0.92, 0.79 and 0.88, 0.86 and 0.95 for total germplasm, pure lines and hybrids, respectively. The coefficient of determination (R2) ranged between 0.72 and 0.92. The best prediction for LA was obtained with hybrid plants (LA ¼ -165.82 þ 5.38LBL þ 16.17LBW) at R2 of 92%. The implication is that we can accurately and affordably predict LA from duo measurements of LBL and LBW in SAS as well as in other crops having similar leaf shapes.
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    Identification of growth stage specific watering thresholds for drought screening in Solanum aethiopicum Shum
    (Scientific Reports, 2020) Nakanwagi, Mildred Julian; Sseremba, Godfrey; Kabod, Nahamya Pamela; Masanza, Michael; Balyejusa Kizito, Elizabeth
    Effective phenotyping for drought resistance is a pre-requisite for identification of modest crop varieties for farmers. For neglected and underutilized crops such as Solanum aethiopicum Shum group, no drought screening protocol based on rigorous iterations has been documented. A split-plot nested treatment structure was arranged in an experiment to identify growth stage-specific watering thresholds for this crop. Three plant growth stages (main plot; seedling, vegetative and flowering), watering regime at plant growth stage (2 regimes; well-watered and drought stressed) and day since last watering at plant growth stage were evaluated for soil moisture content (SMC), leaf wilting score (LWS), number of green leaves per plant (LPP) and leaf blade width (LBW). Highly significant differences (p < 0.001) were found at the different plant growth stages, watering regime (WR) within plant growth stage, and day within WR and plant growth stage. Under drought stress treatment, SMC declined exponentially at each stage. The earliest leaf wilting, reduction in LPP and LBW were generally observed at flowering followed by vegetative and slowest at the seedling stage. For future effective drought phenotyping studies in S. aethiopicum Shum and related crops, we recommend setting minimum drought stress treatments below 18% SMC at which the LWS is ≥2 at the vegetative.
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    Performance of Solanum aethiopicum Shum group accessions under repetitive drought stress
    (Journal of Plant Breeding and Crop Science, 2017) Nakanwagi, Mildred Julian; Sseremba, Godfrey; Masanza, Michael; Balyejusa Kizito, Elizabeth
    Drought is a serious climatic hazard to crop production, more especially when it occurs repeatedly. This created a need to identify repetitive drought tolerant varieties that recover following exposure to drought. Twenty accessions of Solanum aethiopicum Shum group were evaluated for their response to repeated drought exposure in a screen house at Uganda Christian University stressed and well-watered conditions in a split-plot arrangement. Data was collected on growth and yield parameters namely leaf area, plant canopy width, plant height, plant branching, fresh leaf weight, fresh shoot biomass, and harvest index. Exposure of plants to repetitive drought stress led to significant decrease in all evaluated growth parameters at p<0.001 except for plant branching. Similarly, yield parameters exhibited a highly significant difference among accessions and between water levels at p<0.001. Principal component analysis of growth rate traits showed that leaf area contributed to the highest variation for recovery from repetitive drought stress among accessions. The accessions that recovered best from drought stress include SAS108/2015, SAS163/P/2015, SAS183/G/2015, and SAS168/G/2015. For yield parameters, the accessions SAS137/2015, SAS148/2015, SAS108/P/2015, and SAS160/2015 had the highest dry shoot biomass. These findings indicate prospect for improvement of tolerance to repetitive drought stress in S. aethiopicum Shum group.