ABSTRACT. In most cases, in genetic breeding of Arabica coffee, plot size is defined in an empirical manner. It is often based only on the experience of the breeders and the availability of resources, potentially leading to a reduction in precision. Therefore, the aim of this study was to estimate the size of the experimental plot for evaluation of coffee yield. We evaluated two experiments for validation of cultivars with 12 treatments set up in a randomized complete block design with three replicates and plots composed of 50 plants. Each plant was considered as a basic unit. Estimates of ideal plot size were made by maximum curvature of the coefficient of variation, linear-plateau segmented model and by the resampling methods. We discussed the variations in the parameter estimates for different plot sizes. Divergence was seen among the plot sizes estimated by the different methodologies. Increasing the number of plants per plot led to a higher experimental precision to the point that the increase was no longer significant. The plot size recommended for evaluating coffee production is from seven to 19 plants.

Abstract The coffee cultivar Catuaí is among the most successful cultivars in Brazilian agriculture; it has been on the market for more than 40 years. It was obtained by Dr. Alcides Carvalho, a researcher of the Instituto Agronômico de Campinas (IAC), from the cross between ‘Caturra’ and ‘Mundo Novo’ carried out in 1949 for the purpose of joining plant vigor with small plant size. Our aim was to report the activities that culminated in the recommendation of 16 lines of ‘Catuaí’, consisting of eight lines with red fruit and eight with yellow fruit, analyzing the data of several experiments. The decision regarding what to recommend was made in the F1:2 generation, based on two harvests. It became clear that Dr. Alcides should be taken as an example by all breeders, above all in his persistence, scientific rigor, and belief that farmers can be an important ally of breeders.

Abstract Brazilian arabica coffee production is based on a set of highly productive cultivars sexually propagated. All of them are susceptible to coffee leaf miner, Leucoptera coffeella, and most of them are also susceptible to coffee leaf rust, Hemileia vastatrix. Aiming to reduce the selection process of cultivars with multiple resistances to both biotic constraints, the Coffea arabica clones 760, 1059, 1064 and 1215 were evaluated under field conditions. The mean yield of four C. arabica clones was not statistically different from the experimental controls; however, the yield of clone 1059 was 21% higher than the control cultivar Obatã IAC 1669-20. Leaf miner resistance level in all the evaluated clones remained the same as the mother plant's. However, the same did not occur for resistance to H. vastatrix, due to the emergence of new pathogen races. In summary, it is potentially feasible the adoption of clone 1059 as a new clonal cultivar resistant to coffee leaf miner.