Thomas M. Seversike

North Carolina State University, Raleigh, North Carolina, United States

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Publications (5)14.05 Total impact

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    ABSTRACT: Aims Wild soybean accession PI 468917 [Glycine soja (Sieb. and Zucc.)] was examined for traits that could potentially be beneficial for development of drought resistant soybean cultivars. Methods Water use was examined in controlled environment chambers at three temperatures (25, 30, and 35 °C). Root morphology of plants grown in hydroponics was analyzed using digital imaging software. Results Wild soybean had lower transpiration efficiency in producing mass than the domesticated soybean cultivar Hutcheson at all temperatures. As soil dried, wild soybean decreased transpiration earlier (at a higher soil water content) than domesticated soybean, but only at 25 °C. Wild soybean had much greater root length than the modern soybean when grown at 25 or 30 °C in hydroponics, with the increase observed in the 0.25 to 0.50 mm diameter class. Wild soybean’s advantages dissipated at higher growth temperatures. Conclusions Wild soybean populations, potentially, can offer useful traits for improving drought resistance of modern soybean. Sensitive transpiration control in response to soil drying would contribute to ‘slow-wilting’ strategies known to be advantageous for drought resistance, and greater root length would enhance water acquisition from the soil profile. Use of the traits in breeding programs will require extending the temperature range for trait expression.
    Plant and Soil 01/2014; 374(1-2). DOI:10.1007/s11104-013-1757-2 · 3.24 Impact Factor
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    ABSTRACT: A key strategy in soybean drought research is increased stomatal sensitivity to high VPD, which contributes to the 'slow wilting' trait observed in the field. These experiments examined whether temperature of the growth environment affected the ability of plants to respond to VPD, and thus control transpiration rate (TR). Two soybean [Glycine max (L.) Merr.] and four wild soybean [Glycine soja (Sieb. and Zucc.)] genotypes were studied. The TR was measured over a range of VPD when plants were growing at 25°C or 30°C, and again after an abrupt increase of 5°C. In G. max, a restriction of TR became evident as VPD increased above 2.0 kPa when temperature was near its growth optimum of 30°C. 'Slow wilting' genotype PI 416937 exhibited greater TR control at high VPD compared to Hutcheson, and only PI 416937 restrained TR after the shift to 35°C. Three of the four G. soja genotypes exhibited control over TR with increasing VPD when grown at 25°C, which is near their estimated growth optimum. The TR control became engaged at lower VPD than in G. max and was retained to differing degrees after a shift to 30°C. The TR control systems in G. max and G. soja clearly were temperature-sensitive and kinetically definable, and more restrictive in the 'slow wilting' soybean genotype. For the favorable TR control traits observed in G. soja to be useful in soybean breeding for warmer climates, the regulatory linkage with lower temperatures must be uncoupled.
    Physiologia Plantarum 09/2012; 148(1). DOI:10.1111/j.1399-3054.2012.01693.x · 3.26 Impact Factor
  • Functional Plant Biology 01/2012; 39(12):979. DOI:10.1071/FP12172 · 2.57 Impact Factor
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    ABSTRACT: Early-maturing soybean [Glycino max (L.) Merr] cultivars require less irrigation than full-season cultivars and may mature before drought periods most often occur in the midsouthern United States. These cultivars require high plant-population densities for radiation interception and acceptable yields, which increase costs. We hypothesized that seven-leaflet genotypes would have greater leaf area per plant, resulting in more radiation interception and higher yield than near-isogenic three-leaflet genotypes at similar populations. Near-isogenic lines from maturity groups 00 to 1.8 were seeded at rates from 4 to 80 m(-2). The fraction of photosynthetically active radiation (PAR) intercepted by plots was measured using digital imagery and used to estimate cumulative intercepted PAR (CIPAR). Although seven-leaflet isolines had greater leaf area per leaf than three-leaflet isolines, leaf area per plant was similar between three- and seven-leaflet isolines because the three-leaflet isolines had a slightly greater number of main-stem leaves than seven-leaflet isolines. Generally, seven-leaflet isolines had 10 to 21% greater CIPAR at populations <= 40 m(-2) compared to three-leaflet isolines. At populations <= 20 m(-2), seven-leaflet isolines generally had higher yields than three-leaflet isolines, but yields at these low populations were inherently low and agronomically unacceptable.
    Crop Science 01/2009; 49(1). DOI:10.2135/cropsci2007.08.0472 · 1.48 Impact Factor
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    ABSTRACT: The seven-leaflet character of soybean [Glycine max L. (Merr.)] is a single recessive trait conditioned by the lf ( 2 ) gene. The lf ( 2 ) gene is located on linkage group (LG) 16 of the classical soybean genetic map, but it has not been placed on the molecular map. The objective of this research was to identify the location of the lf ( 2 ) gene on the soybean molecular map using simple sequence repeat (SSR) markers. A backcross breeding method was used to create three- and seven-leaflet near-isogenic lines in genetic backgrounds of 'Traill', 'MN1401', and 'MN1801'. Eight mapping populations were derived from eight single heterozygous Lf ( 2 ) lf ( 2 ) plants. A total of 482 SSR markers that covered approximately every 10-20 cM of all soybean molecular LG were used to screen the mapping populations for polymorphisms. For the 115 SSRs that were identified as polymorphic, possible linkage between the lf ( 2 ) gene and the polymorphic SSR markers was determined. One SSR marker from the LG B1, Sat_272, was linked (LOD > 4.0) to the lf ( 2 ) gene in the Traill and MN1401 derived populations, with map distances ranging from 2.8 to 11.2 cM. Two additional markers (a SSR, Sat_270 and a SNP, A588c) located on LG B1 were also polymorphic and were identified as linked to the lf ( 2 ) gene in one of the populations. This research was successful in mapping the lf ( 2 ) gene to LG B1 of the soybean molecular map and therefore, provides evidence that molecular LG B1 corresponds to classical LG 16.
    Theoretical and Applied Genetics 08/2008; 117(2):143-7. DOI:10.1007/s00122-008-0759-6 · 3.51 Impact Factor