ABSTRACT:This study aimed at assessing the interaction of potassium (K) and boron (B) in the coffee rust intensity in a nutrient solution. The experiment which was performed in a greenhouse was set up in the randomized complete block design (DBC) with four replicates. The experimental unit involved a single vase with two Catuaí Vermelho (IAC 144) cultivars. The treatments included five doses of boron (0.05, 0.50, 1, 2 and 4 mg L -1 ) and five of potassium (4.0, 5.0, 6.0, 7.0 and 8.0 mmol L -1 ), totaling to 25 treatments in a factorial variance analysis. All the coffee seedling leaves were inoculated with Hemileia vastatrix. For the next 24 hours, the vases were covered with a black plastic bag, and left in the greenhouse to ensure favorable conditions for the fungal infection. A significant interaction was observed between the potassium (K) and boron (B) nutrients in coffee rust intensity. As the boron dose increased from 0.05 to 2.0 mg L -1 , the coffee rust intensity was observed to rise. From the 0.50 mg L -1 dose of B a drastic drop in the dry plant mass was observed, which reached zero index at the highest boron dose due to phytotoxicity. ), totalizando 25 tratamentos em esquema fatorial de análise de variância. A inoculação foi realizada em todas as folhas das mudas de cafeeiro até o ponto de escorrimento. Posteriormente, os vasos foram cobertos com saco plástico preto por 24 horas, permanecendo na casa de vegetação com o objetivo de proporcionar condições adequadas para o fungo penetrar e iniciar o processo de infecção. Ocorreu interação significativa entre os nutrientes potássio (K) e boro (B) na intensidade da ferrugem do cafeeiro. A partir da dose de 0,05 até 2,0 mg L -1 de B foi observado aumento da intensidade da ferrugem do cafeeiro. A partir da dose 0,50 mg L -1 de B houve redução drástica da massa da planta seca, atingindo índice zero na maior dose de B, devido a fitotoxidez.
Termos para indexação:Hemileia vastatrix, nutrição de plantas, potássio, boro.