A seca é um dos fatores que limitam o desenvolvimento e a produtividade do cafeeiro. O objetivo deste estudo foi analisar a anatomia de folhas desenvolvidas nos períodos chuvoso e seco, em nove cafeeiros de Coffea arabica L., descritos anteriormente como tolerantes ou sensíveis a déicit hídrico, para identiicar caracteres estruturais de tolerância à seca. Foram mensurados o tamanho e a densidade de estômatos e células epidérmicas, a espessura das epidermes e do mesoilo, o diâmetro do pecíolo e da nervura principal, a espessura do loema e xilema na nervura principal e no pecíolo e o diâmetro e a frequência de elementos de vasos do xilema. Diferenças observadas entre a estrutura foliar dos cafeeiros avaliados e as condições de desenvolvimento da folha (períodos chuvoso e seco) indicaram que há uma plasticidade anatômica favorável em relação às condições de seca. Espessuras maiores do parênquima paliçádico e do limbo total e raios maiores do loema e xilema no pecíolo e na nervura principal foram considerados características estruturais favoráveis para suportar a escassez de água e estas poderiam ser utilizadas como critérios para selecionar cultivares tolerantes à seca. Foram considerados mais adaptados à seca os seguintes cafeeiros: Geisha, Semperlorens, BA10, IAC H 8105-7, IAC H 8421-2 e a cultivar Catuaí Vermelho IAC 81.

Characterization of resistance response to pathogens is a fundamental strategy in plant breeding programmes. Thus, in this study, we developed an effective inoculation method for resistance tests of bacterial halo blight (BHB), caused by Pseudomonas syringae pv. garcae on coffee. Firstly, aggressiveness of eight selected bacterial strains as well as seven mixed strains was assessed on coffee seedlings of Mundo Novo IAC 376‐4 cultivar. Two experiments were conducted comparing three inoculation techniques: initially, we compare the methods of sprinkling and multiple needles on four cultivars of Coffea arabica; later, four cultivars and seven genotypes were compared for the multiple needles method and the abrasion technique. Severity was evaluated according a disease rating scale (DRS), considering either leaf surface area affected for sprinkling, or affected inoculated area for inoculation by multiple needles and abrasion. The area under the disease progress curve of disease (AUDPC) was calculated considering weekly evaluations of disease from seven until 42 days postinoculation (DPI). The standard deviation (SD), coefficient of variation (CV) and confidence interval (CI) variables were used to denote the effectiveness of the methods. According to the results, strain IBSBF 1197 was the most aggressive, and three other strains showed high aggressiveness. All inoculation methods were able to discriminate the resistance response to BHB, wherein the sprinkling method was less efficient than multiple needles and abrasion technique was more efficient than multiple needles. In addition, disease evaluations at 14 DPI showed a high correlation coefficient with area under AUDPC at 42 DPI, validating the early selection to BHB. Results of inoculation methods indicated the abrasion on first pair of leaves, together with evaluations on fourteenth DPI, as the most promising technique for early selection on coffee breeding to BHB.

RESUMOO presente estudo objetivou avaliar a resistência de plantas de Coffea arabica, C. canephora e de híbridos interespecíficos, à cercosporiose (Cercospora coffeicola), importante doença da cultura do cafeeiro. The most susceptible materials were Robusta IAC 1653-7, Apoatã IAC 2258, Híbrido de Timor IAC 1559-13, Bourbon Vermelho, and Bourbon Amarelo, with levels of incidence that varied from 81.6 to 63.1% in the first experiment, and from 70 to 93.3% in the second, and severity (graded scale 1-6) from 2.92 and 3.42 in the first experiment to 2.79 and 3.64 in the second. The most resistant materials were Piatã IAC 387, Ouro Verde IAC H5010-5 and Tupi IAC 1669-33, with incidence between 28.4 and 35.5 % in the first experiment and between 21.1 and 55.6%, in the second, and severity that varied from 1.44 to 1.73 in the first experiment to 1.28 to 1.88 in the second.

IAC 125 RN was derived from a cross between the coffee cultivar Villa Sarchí and the Hibrido de Timor CIFC 832/2. The coffee trees are short and resistant to races 1 and 2 of the nematode Meloidogyne exigua and to all races of coffee rust, Hemileia vastatrix, present in Brazil. Brazil.