Browsing by Author "Tukamuhabwa, P."

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    Genetic Components of Pod Shattering in Soybean
    (Euphytica, 2002-05-16) Tukamuhabwa, P.; Rubaihayo, P.; Dashiell, K.E.
    Half diallel crosses among ten pure breeding lines of soybean were made in 1997 and 1998 to study the inheritance of pod shattering in soybean. Evaluation for pod shattering among F2 segregating populations was carried out in an oven set at 80 °C for 12 hours. Diallel analysis was carried out to estimate genetic parameters and detect presence of non allelic interaction of genes affecting pod shattering. Hayman's diallel analysis indicated significant variation of Wr + Vr and Wr – Vr over arrays, suggesting epistatic gene action. Similarly results from a joint regression coefficient over replications were significantly (p < 0.05) different from unity and zero, suggesting presence of non allelic interaction of genes. The intercept was positive, suggesting partial dominance for the shattering trait. Both general combining ability (GCA) and specific combining ability (SCA) effects were significant (p < 0.05).
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    Potential for soybean rust tolerance among elite soybean lines in Uganda
    (Crop protection, 2009) Oloka, Herbert K.; Tukamuhabwa, P.; Sengooba, T.; Adipala, E.; Kabayi, P.
    Soybean rust, (Phakopsora pachyrhizi), currently the most devastating disease of soybeans worldwide, is known to challenge single resistance genes deployed against it and therefore, disease tolerance is indisputably the most viable measure in controlling the pathogen. Studies were conducted at Namulonge in Central Uganda to assess the level of tolerance to soybean rust among selected elite soybean lines. Seven elite lines together with three local checks were tested in a split-plot design where some plots were protected with fungicide to estimate the level of tolerance to soybean rust. The experimentwas conducted for three cropping seasons beginning second rains of 2005. A rust tolerance index (RTI) was computed for each test line as the ratio of yield from unprotected plots to yield from protected plots. The study showed that high levels of tolerance to soybean rust were present in the test lines. The soybean lines that showed high levels of tolerance included MNG 10.3 and MNG 3.26 all showing RTIs higher than 0.93. These lines also out-yielded the local checks by about 400 kg ha 1 and are recommended for multi-location testing.
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    Potential for yield loss reduction and profitability assessment of pesticide control of groundnut leaf miner among soybean genotypes
    (African Journals Online (AJOL), 2019-05-17) Namara, M.; Karungi, J.; Edema, R.; Gibson, P.; Tukamuhabwa, P.
    Groundnut leaf miner (GLM) is currently a threat to soybean production in Uganda due to the great yield losses as a result of the severe damage it causes on leaves leading to reduced photosynthetic area. GLM is a fairly new pest on soybean in Uganda, having initially been observed in soybean fields in 2011 in eastern Uganda. The objective of this study was to determine the yield loss caused by the groundnut leaf miner and effectiveness and profitability of commonly used pesticides for the control of the groundnut leaf miner (Aproaerema modicella Deventer) (GLM), when tested with popular soybean (Glycine max) genotypes grown in Uganda. In a split plot RCBD design, pesticide protection (treated vs. untreated) formed the main plots; and six commercial soybean varieties (Maksoy 1N, 2N, 3N, 4N, 5N; and Namsoy 4M) as subplots. The study was done in two locations in eastern Uganda (Iki Iki District Agricultural Training and Information Centre (Iki Iki DATIC) and National Semi-Arid Resources Research Institute, Serere (NaSARRI) with two planting rounds at Iki Iki. These sites were chosen because they are hot spots for GLM. GLM severity and soybean yield were significantly affected by the pesticide protection. Overall, percentage grain yield losses caused by GLM on the different soybean varieties ranged from 37.3% to 65.7% and the highest loss was displayed by Maksoy 5N. Grain yield loss recorded at Iki Iki DATIC (53.1%) was remarkably higher than that recorded at the NaSARRI (49.1%). Economic analysis showed marginal returns to be dependent on location, with the Iki Iki DATIC having 0.6 and NaSARRI 1.1. This study has shown that the groundnut leaf miner, a recently emergent pest of soybean is becoming a big threat to soybean production and that chemical control alone may not be economical in managing the pest.
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    Reaction of Exotic Soybean Germplasm to Phakopsora pachyrhizi in Uganda
    (Plant Disease, 2008) Oloka, H. K.; Tukamuhabwa, P.; Sengooba, T.; Shanmugasundram, S.
    Host plant resistance is the best long-term strategy for managing soybean rust (Phakopsora pachyrhizi) in endemic areas. Resistance breeding efforts are hampered by the presence of several races of the pathogen that often overcome single resistance genes deployed against them. In Uganda, only two soybean cultivars show moderate resistance to Phakopsora pachyrhizi, but this is likely to break down given the aggressive nature of the pathogen. A total of 25 rust tolerant or resistant accessions were imported from the Asian Vegetable Research and Development Centre and screened at Namulonge, in central Uganda. Only 10 accessions, G 33, G 8527, G8586, G 8587, GC 60020-8-7-7-18, GC 87016-11-B-2, GC 87021-26-B-1, SRE-D-14A, SRE-D-14B, and SS 86045-23-2, showed no rust symptoms at growth stage R6 during the three seasons of testing. Soybean rust resistance genes Rpp1, Rpp3, and Rpp4 did not confer resistance at Namulonge; gene Rpp2 was effective.