O café é a segunda principal commodity no mercado mundial. A espécie Coffea arabica é uma das principais espécies cultivadas no mundo. No entanto, a cultura hospeda uma grande variedade de patógenos e pragas. Os patógenos Hemileia vastatrix e Colletotrichum kahawae são as doenças mais importantes da cultura, e a praga bicho-mineiro, impacta severamente a produtividade e qualidade de bebida. Assim, como forma de controle, o desenvolvimento de cultivares resistentes, com a utilização de marcadores moleculares auxiliam no progresso de melhoramento genético da cultura. O objetivo do trabalho foi identificar cafeeiros portadores de genes de resistência para as principais doenças do café; determinar a diversidade genética por meio de características morfológicas e estimar os parâmetros genéticos e os ganhos com a seleção utilizando a metodologia de modelos mistos (REML/BLUP). O estudo foi composto por duas populações, a primeira, os cafeeiros em geração F 2 são provenientes do cruzamento entre cultivar resistente a ferrugem e CBD e outra ao bicho-mineiro, enquanto que a segunda, são originados de cruzamentos de cafeeiros arábicas com fontes de resistência (seleção indiana). A identificação de cafeeiros resistentes foi feita fenotipicamente e/ou molecularmente. A análise de diversidade genética foi baseada na distância generalizada de Mahalanobis e a seleção fenotípica, por meio do procedimento REML/BLUP. Ambas populações apresentaram resistência múltipla para as principais doenças com diferentes combinações. Com base nas análises utilizando o método REML/BLUP, foi possível selecionar cafeeiros promissores por serem geneticamente divergentes e complementares pela análise de agrupamento e por proporcionar ganhos com a seleção principalmente para a característica infestação de bicho- mineiro. Além disso, foi possível observar que os materiais em desenvolvimento apresentam superioridade em relação as cultivares comerciais. Palavras-chave: Hemileia vastatrix. Colletotrichum kahawae. Melhoramento preventivo. Piramidação de genes.
Baby corn maize (Zea mays L.) is a highly profitable alternative to farmers due to its short crop duration, being harvested at the juvenile stage. It demands large amounts of nutrients in a short time, especially nitrogen, which is responsible for the rapid development of crop. This study aimed to evaluate the effect of topdressing application of different doses of nitrogen on the vegetative and spikelet productivity features in the baby corn crop in Janaúba -Minas Gerais. The experiment was laid out in randomized block design with three replications and four treatments. The treatments comprised four doses of nitrogen (0, 40, 80 and 120 kg ha -1 N applied as urea) top dressed at the V6 (sixty leave with visible auricle) growth stage, which occurs 30 days after sowing the seed. Nitrogen topdressing doses did not interfere in vegetative characteristics of baby corn cultivar Al Bandeirante, but the productivity of spikelet responded to the increasing doses of nitrogen, being the highest productivity at a dose of 120 kg ha -1 N.
The insufficiency of morphological descriptors reveals the importance of studies related to this topic for the genetic improvement of soybean, with attention to the possible descriptors measured in early stages of plant development which allows obtaining fast results. The aim of this work was to estimate the coefficient of repeatability of some morphological descriptors in the early stages of development of soybean and the minimum number of evaluations necessary to predict the real value of genotypes. Five (5) experiments were carried out with 124, 93, 90, 16 and 16 genotypes of soybean for the first, second, third, fourth, and fifth experiment, respectively, with characteristics combined at the stage V3. It was concluded that the length of the first internode requires fewer measurements compared to other measured characteristics. With six measurements, it was possible to obtain 95% and 90% reliability for plant height in V3 and first internode length, respectively, by the methods ANOVA, CP (correl), CP(cov) and AE(correl). With seven measurements, it was obtained 90% reliability for the epicotyl length for all methods used; 85% for the petiole length of unifoliate leaf by method of CP(cov) and 90% by methods ANOVA, CP(correl), AE(correl). With 15 measurements, it was possible to obtain 90% reliability for the hypocotyl length, petiole length of trifoliate leaf and the angle formed by the insertion of the petioles of the unifoliate leaf for all methods used; and, for the rachis length of the first trifoliate leaf, 37 measurements would be necessary for reliability of 90% by methods of ANOVA, CP(correl), CP(cov) and AE(correl).
The water deficit in arid and semiarid regions and the high cost of fertilizers are factors for the study of application of sewage on agricultural crops. Therefore, the objective of this study was to evaluate the effect of application of different doses of treated sewage from the tertiary treatment (TS-3), and mineral fertilizer on the yield and production components of common bean plants. The experiment was conducted in Janaúba, MG, Brazil, using a randomized block design, with four repetitions, in a split-plot scheme, with five treatments in the plots consisting of potassium (K2O) applications at the dose required by common bean plants via clear water + 40 kg ha-1 of K2O mineral (Control), and TS-3 applications supplying 20, 40, 60 and 80 kg ha-1 of K2O, and two cultivars in the subplots, BRS-MG-Madreperola and Ouro Negro. The cultivar Ouro Negro was more responsive than the cultivar BRS-MG-Madreperola to the different TS-3 doses and mineral fertilizer regarding their leaf, stem, and shoot dry weights, and their ratios. However, the highest doses of K2O via TS-3 affected negatively the grain yield in common bean plants. The dose of 20 kg ha-1 of K2O via TS-3 is the best dose for common bean plants.
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