P.H. Graham's research while affiliated with University of Minnesota Duluth and other places

... As regiões sul e centro-oeste do Brasil são as que possuem maior concentração de área plantada de soja totalizando 78,2% de toda a área destinada ao cultivo (Hungria et al., 2005;Hirakuri et al., 2018). ...

... Inoculant rhizobia are available for some of these legumes ), but in many cases the species and even the genus to which the rhizobia belong are still unknown (Graham 2005). Adding complexity to this matter, cross inoculation can occur among some of these genera, including Amorpha, Astragalus, and Dalea, as well as Phaseolus with unknown implications (Bernal et al. 2004;Cloutier et al. 1996;Graham 2005;Graham et al. 1999;Tlusty et al. 2005). ...

... 17 Nitrogen fixation helps in the improvement of soil fertility and crop production. 18 Azotobacter can convert the nitrogen present in atmosphere into ammonia which can be taken up by plants and gets utilized in plant body. 19 At the time when they are fixing the nitrogen the plant become resistant to oxygen because of production of nitrogenase. ...

... Hence, competition of soil rhizobial populations is an important biotic factor that precludes nodulation by inoculated strains. Although several attempts were made to improve the competitiveness of inoculants, including through bacterial genetics (Toro, 1996;Da Costa Coutinho et al., 1999;Sadowski and Graham, 1999;Amarger, 2002, Okazaki et al., 2003, optimization of plant variety-bacterial strain compatibility (Herridge and Rose, 2000;Siriluck and Sadowsky, 2008), and enhancement of inoculant formulations (Smith, 1992, López-García et al., 2001, López-García, 2004, little success was obtained under fi eld conditions. Th is was particularly the case when the size of the competitor populations was higher than 10 3 infective propagules g -1 of soil, which is the situation in the center of Argentinean soybean cropping areas. ...

... The coefficient of correlation between NN and -PAT% (r = 0.27; p < 0.01) was similar to that reported by Houngnandan et al. (2008) between nodule number and δ 15 N (r = 0.325*) in a diverse group of soybean cultivars. Additionally, Pazdernik, Graham, and Orf (1997) studied a soybean population to investigate early nodulation traits and found that %Ndfa at R5 was significantly correlated with nodule fresh weight (r = 0.33; p < 0.01). ...

... The hypothesis of this work was that indigenous rhizobium isolated from roots and rhizosphere soil of M. axillare can achieve the most efficient symbiosis and serve as the basis for the production of an inoculant to the legume. As pointed out by Sadowsky and Graham [16], a way of multiplication of rhizobium strains is through their multiplication in nodules that further decompose and liberate them into the soil. If nodulated plants in a low-fertility soil are well developed, the chances that the nodules host efficient strains are favorable. ...

... Soybean has a high demand for N to achieve greater grain yield and seed protein content (Fabre and Planchon, 2000). However, N fertilization is not recommended due to the high SNF efficiency in Brazil (Hungria et al., 2006a;2006b). The exception is at sowing, when a maximum rate of 20 kg N ha −1 can be applied to supply N without affecting SNF establishment (Embrapa, 2013). ...

... The use of more effective, competitive, and adapted strains to inoculate common bean, such as R. tropici and R. freirei strains recommended in Brazil, has already shown that it is possible to attenuate the competitiveness of resident rhizobia and achieve improvements in nodulation, nitrogen fixation, and yield for this crop (Hungria et al., 2003). Strains with high nodule-forming efficiency (i.e., initiating and sustaining an infection rapidly and efficiently) are often found to have a competitive advantage over those that are slower and less efficient (McDermoti and Graham, 1990;Vlassak et al., 1997). Therefore, the higher nodulation ability of AzR18 and AzR19 may represent a competitive advantage for nodule occupation of common bean in the presence of indigenous soil rhizobia and represent and additional advantage as compared to CIAT899. ...

... también mostraron una respuesta variable entre las especies con aumentos signifi cativos en la MS aérea de las plantas. En particular, Beyhaut et al. (2006b) obtuvieron incrementos de 100% de biomasa vegetal de D. illinoensis con respecto a plantas sin inocular. ...

... Although our approach to estimating d 15 N a was prone to error, we suggest that this error was likely no greater than what would be engendered by more traditional methods (Ledgard, 1989;Unkovich et al., 1994;Okito et al., 2004). In particular, our approach avoided biases that arise from deriving B values with one set of rhizobial strains that differ from those that inhabit root nodules in the field (Byun et al., 2004). Summed across harvests within years, annual Ndfs in N 2 -fixing alfalfa (137 kg N ha 21 ) was greater than Ndfs in nonfixing alfalfa alone (87 kg N ha 21 ), but equal to Ndfs of nonfixing alfalfa plus weeds (144 kg Nha 21 ). ...