Strategy to identify resistance to white mould associated with high yield for irrigated common bean in Brazil

Abstract

Development of common bean cultivars with partial white mould resistance through breeding techniques has been a challenge in Brazil. As yet, lines/cultivars from breeding programmes have not been investigated for resistance; therefore, this study screened 107 lines/cultivars for their reactions to white mould in 14 preliminary trials conducted under irrigation. Thirteen resistant lines/cultivars (three of Andean origin) and six Mesoamerican cultivars (three intermediately resistant and three susceptible) were selected for further investigation. These lines/cultivars and the resistant control A195 were evaluated in six advanced trials and two straw tests to assess the effectiveness of the screening procedure. In 11 preliminary trials, screenings were performed under moderate/high or higher disease pressure. These pressures occurred in two advanced trials in which, when yields were averaged across moderate/high and high pressures, 10 Mesoamerican lines/cultivars selected for resistance yielded 14%, 23%, and 38% more than intermediately resistant cultivars, A195, and susceptible cultivars, with median disease ratings (1–9 scale) of 4.5, 5.7, 5.7, and 6.7, respectively. In the straw test, three Andean lines/cultivars (A195 included) and two susceptible cultivars in the field were among those with the highest levels of physiological resistance. Thus, field rating under high disease pressure and greenhouse rating did not correlate significantly, suggesting that field trials are critical to evaluating resistance and to identifying high‐yielding beans. Therefore, lines/cultivars from breeding programmes assessed in field trials may provide a low cost and fast way to identify high‐yielding bean cultivars with partial resistance to white mould in the subtropical southern hemisphere.

Strategy to identify common beans with resistance to white mould for dry‐irrigated areas: Additional evidence

“…However, G1, G2 yielded 43% more and produced 33% less sclerotia than G3. All these results confirm and reinforce the findings of the research conducted by Lima et al (2020). These for releasing cultivars with partial resistance may expedite the process compared with traditional breeding methods (Schwartz & Singh, 2013).…”

“…G1 had seven Mesoamerican genotypes; G4 had two Mesoamerican cultivars; and G5 had three Mesoamerican cultivars (Table 2). These 12 genotypes were selected in VCU trials conducted between 2008 and 2011 and subsequently evaluated in six advanced trials and two straw tests by Lima et al (2020). In each trial, WM pressure was considered low when the mean of the susceptible group (G5) exhibited WMI ≤25% or WMSI ≤15%; low/moderate, 26%-45% of WMI or 16%-30% of WMSI; moderate, 46%-65% of WMI or 31%-45% of WMSI; moderate/high, 66%-85% of WMI or 46%-60% of WMSI; and high, >85% of WMI or >60% of WMSI (adapted from Lima et al, 2019).…”

“…We evaluated canopy closure, canopy height, and foliar diseases at the R7 growth stage (pod filling); lodging, WMI, and WMSI at harvest; seed yield; and weight of sclerotia. Canopy closure, canopy height, lodging (1-to-9 scale), and seed yield were evaluated as described by Lima et al (2020). Foliar diseases, canopy height, lodging, and seed yield were evaluated over the six trials.…”

Characterization of Novel Brazilians Rhizosphere Soil Trichoderma spp. to Select Effective Biocontrol Agents against Sclerotinia sclerotiorum on Beans

“…Beans are one of the most important crops based on harvested areas and global production of this legume [1]. Brazil is the world's largest producer of common bean (Phaseolus vulgaris L.) with an annual production of 3,250,000 t and an average grain yield of 1,024 kg/ha [2].…”

“…Brazil is the world's largest producer of common bean (Phaseolus vulgaris L.) with an annual production of 3,250,000 t and an average grain yield of 1,024 kg/ha [2]. Although this crop is susceptible to several diseases, especially in large cultivated areas, few of them are as harmful as white mold [1,3], caused by the soil fungus Sclerotinia sclerotiorum [(Lib.) de Bary (1884)].…”