Incidence of base rot and wilt, sanitary severity and influence about seed pathology by cultivars of common bean (Phaseolus vulgaris) / Incidência de podridão-do-colo e severidade fitossanitária e impacto na patologia de sementes de cultivares comerciais de feijoeiro-comum (Phaseolus vulgaris)

The objective of this work was to conduct a temporal evaluation of incidence of rot base and sanitary severity, and to relate the impact on the seed pathology of common bean cultivars. In the 2015-2016 harvest, in the city of Ipameri, Goiás, ten cultivars of common bean were evaluated (BRS Estilo©, BRS Pérola©, IPR Tangará©, IPR Tuiuiú©, IPR Uirapuru©, IAC Milênio©, Imperador©, IAC F3 R2©, IAC OTG© and IPR Campos Gerais©) and distributed into five blocks, totaling 40 experimental units. The incidence of wilt and base rot and sanitary severity were analyzed by taking ten random samples per block at 21, 28, 56, 63 and 69 days after planting. At the end of 120 days, a total of 20 plants were harvested per cultivar, and 250 seeds were harvested for application of the Blotter Test method. From 21 to 69 days after planting, the cultivars BRS Pérola© and IPR Campos Gerais© deserve to be highlighted for presenting the lowest incidence of wilt in the reproductive and vegetative cycles. The cultivar BRS Pérola© showed the lowest incidence of wilt and sanitary severity. In the analysis of harvested seeds, the cultivar BRS Pérola© presented high physiological quality for all evaluated parameters. On the other hand, Cramberry (OTG)© showed low physiological potential in germination and vigor tests.(AU)

O objetivo deste trabalho foi realizar uma avaliação temporal da incidência de podridão-do-colo e severidade fitossanitária, e relacionar o impacto na patologia de sementes de cultivares comerciais de feijoeiro-comum. Na safra 2015-2016, no município de Ipameri, Goiás, foram avaliados dez cultivares de feijoeiro (BRS Estilo©, BRS Pérola©, IPR Tangará©, IPR Tuiuiú©, IPR Uirapuru©, IAC Milênio©, Imperador©, IAC F3 R2©, IAC OTG© e IPR Campos Gerais©), distribuídos em cinco blocos, totalizando 40 unidades experimentais. Analisou-se temporalmente a incidência da murcha e ­podridão-do-colo e a severidade fitossanitária tomando dez amostragens aleatórias por bloco aos 21, 28, 56, 63 e 69 dias após o plantio. Ao final dos 120 dias, colheu-se um total de 20 plantas por cultivar, sendo extraídas 250 sementes de cada para aplicação do método "Blotter Test". Dos 21 aos 69 dias após o plantio, merecem destaque os cultivares BRS Pérola© e IPR Campos Gerais©, por apresentarem as menores incidências de murcha nos ciclos reprodutivo e vegetativo. O cultivar BRS Pérola© apresentou as menores incidências de murchas e severidade fitossanitária. Na análise de sementes colhidas, o cultivar BRS Pérola© apresentou elevada qualidade fisiológica para todos os parâmetros avaliados. Em contrapartida, o cultivar Cramberry (OTG)© mostrou baixo potencial fisiológico nos testes de germinação e vigor.(AU)

Antagonistic endophytic bacteria associated with nodules of soybean (Glycine max L. ) and plant growth-promoting properties

Abstract A total of 276 endophytic bacteria were isolated from the root nodules of soybean (Glycine max L.) grown in 14 sites in Henan Province, China. The inhibitory activity of these bacteria against pathogenic fungus Phytophthora sojae 01 was screened in vitro. Six strains with more than 63% inhibitory activities were further characterized through optical epifluorescence microscopic observation, sequencing, and phylogenetic analysis of 16S rRNA gene, potential plant growth-promoting properties analysis, and plant inoculation assay. On the basis of the phylogeny of 16S rRNA genes, the six endophytic antagonists were identified as belonging to five genera: Enterobacter, Acinetobacter, Pseudomonas, Ochrobactrum, and Bacillus. The strain Acinetobacter calcoaceticus DD161 had the strongest inhibitory activity (71.14%) against the P. sojae 01, which caused morphological abnormal changes of fungal mycelia; such changes include fracture, lysis, formation of a protoplast ball at the end of hyphae, and split ends. Except for Ochrobactrum haematophilum DD234, other antagonistic strains showed the capacity to produce siderophore, indole acetic acid, and nitrogen fixation activity. Regression analysis suggested a significant positive correlation between siderophore production and inhibition ratio against P. sojae 01. This study demonstrated that nodule endophytic bacteria are important resources for searching for inhibitors specific to the fungi and for promoting effects for soybean seedlings.