Abstract Microorganisms associated with organic management are essential in nutrient transformation and release for plant use. The present study aimed to isolate, identify and characterize plant growth promoting diazotrophic rhizobacteria associated with sugarcane under organic management. Rhizospheres of organic sugarcane varieties IAC 911099 and CTC4 were sampled and inoculated onto nitrogen free NFb and Burk media. The isolated microorganisms were screened in vitro concerning their ability to produce plant growth promoting factors. Eighty-one bacteria were isolated; 45.6% were positive for the nifH gene and produced at least one of the evaluated plant growth promotion factors. The production of indole-3-acetic acid was observed in 46% of the isolates, while phosphate solubilization was observed in 86.5%. No isolates were hydrogen cyanide producers, while 81% were ammonia producers, 19% produced cellulases and 2.7%, chitinases. Microorganisms belonging to the Burkholderia genus were able to inhibit Fusarium moniliforme growth in vitro. Plant growth promoting microorganisms associated with organic sugarcane, especially belonging to Burkholderia, Sphingobium, Rhizobium and Enterobacter genera, can be environmentally friendly alternatives to improve sugarcane production.

Foi avaliada a reação de 23 genótipos de feijoeiro comum (Phaseolus vulgaris) à mancha angular causada por Phaeoisariopsis griseola, utilizando os isolados monospóricos Ig 664 e Ig 669, caracterizados como os patótipos 63.23 e 63.19, respectivamente. Quatorze dias após a semeadura (estádio V3), as plantas foram inoculadas com uma suspensão contendo 2,5 x 10(4) conídios/mL, nas faces adaxial e abaxial da primeira folha trifoliolada. A avaliação dos sintomas foi efetuada aos 14 e 18 dias após a inoculação, utilizando-se uma escala variando de 1 (sem sintomas) a 9 ( > 25% da área foliar com lesões de mancha angular). Das cultivares analisadas, BRS Valente, CNFC 10281, CNFP 10138, BRS Grafite, BRS Requinte, BRS Pontal, MAR 02, Cornell 49-242 e AND 277 foram resistentes aos dois isolados. As cultivares Carioca Rubi, CNFC 9504, CNFC 10150 e Soberano foram suscetíveis aos dois patótipos testados. O patótipo 63.23 foi o mais virulento. As novas fontes de resistência à mancha angular identificadas neste trabalho podem ser utilizadas em programas de melhoramento do feijoeiro comum, que visem incorporar resistência em novas cultivares.

Twenty-three common bean (Phaseolus vulgaris) genotypes were tested for reaction to angular leaf spot disease caused by Phaeoisariopsis griseola in the greenhouse. All genotypes were tested with monosporic isolates Ig 664 and Ig 669, characterized as pathotypes 63.23 and 63.19, respectively. Fourteen-day-old plants (vegetative stage V3) were inoculated with a suspension containing 2.5 × 10(4) conidia/mL. This suspension was applied to the upper and lower leaf surfaces. Disease symptoms were evaluated 14 and 18 days after inoculation by using a rating scale varying from 1 (no symptoms) to 9 (> 25% of leaf area with angular leaf spot lesions). Culivars BRS Valente, CNFC 10281, CNFP 10138, BRS Grafite, BRS Requinte, BRS Pontal, MAR 02, Cornell 49-242 and AND 277 showed resistance to both isolates. Cultivars Carioca Rubi, CNFC 9504, CNFC 10150 and Soberano were susceptible to both pathotypes. Pathotype 63.23 was the most virulent. The new resistance sources identified in this work could be used in common bean breeding programs aiming to incorporate resistance to angular leaf spot in new common bean cultivars.