Fusarium virguliforme is a soil borne root pathogen that causes sudden death syndrome (SDS) in soybean [ Glycine max (L.) Merrill]. Once the fungus invades the root xylem tissues, the pathogen secretes toxins that cause chlorosis and necrosis in foliar tissues leading to defoliation, flower and pod drop and eventually death of plants. Resistance to F . virguliforme in soybean is partial and governed by over 80 quantitative trait loci (QTL). We have conducted genome-wide association study (GWAS) for a group of 254 plant introductions lines using a panel of approximately 30,000 SNPs and identified 19 single nucleotide polymorphic loci (SNPL) that are associated with 14 genomic regions encoding foliar SDS and eight SNPL associated with seven genomic regions for root rot resistance. Of the identified 27 SNPL, six SNPL for foliar SDS resistance and two SNPL for root rot resistance co-mapped to previously identified QTL for SDS resistance. This study identified 13 SNPL associated with eight novel genomic regions containing foliar SDS resistance genes and six SNPL with five novel regions for root-rot resistance. This study identified five genes carrying nonsynonymous mutations: (i) three of which mapped to previously identified QTL for foliar SDS resistance and (ii) two mapped to two novel regions containing root rot resistance genes. Of the three genes mapped to QTL for foliar SDS resistance genes, two encode LRR-receptors and third one encodes a novel protein with unknown function. Of the two genes governing root rot resistance, Glyma . 01g222900 . 1 encodes a soybean-specific LEA protein and Glyma . 10g058700 . 1 encodes a heparan-alpha-glucosaminide N-acetyltransferase. In the LEA protein, a conserved serine residue was substituted with asparagine; and in the heparan-alpha-glucosaminide N-acetyltransferase, a conserved histidine residue was substituted with an arginine residue. Such changes are expected to alter functions of these two proteins regulated through phosphorylation. The five genes with nonsynonymous mutations could be considered candidate SDS resistance genes and should be suitable molecular markers for breeding SDS resistance in soybean. The study also reports desirable plant introduction lines and novel genomic regions for enhancing SDS resistance in soybean.

O objetivo deste trabalho foi avaliar, em doses crescentes de fósforo, o efeito de lâminas de irrigação no teor foliar de fósforo de cafeeiros em estágio de primeiro ano de produção. O plantio (Topázio MG-1190) foi realizado em janeiro de 2010 e os tratamentos diferenciados a partir de novembro de 2011. Utilizou-se o delineamento experimental em blocos ao acaso com três repetições, com tratamentos dispostos no esquema fatorial 5 x 4 os quais se compunham por cinco lâminas de irrigação correspondentes às frações (0,4; 0,7; 1,0; 1,3 e 1,6) da lâmina calculada pelo coeficiente de cultura e quatro doses de fósforo (0, 80, 240 e 720 kg ha-1). Foi utilizado o sistema de irrigação por gotejamento enquanto a adubação fosfatada (monoamônio fosfato purificado) foi feita via fertirrigação, em doze parcelamentos iguais durante o ano. Foram avaliados os teores foliares de fósforo aos dois, quatro, seis, oito, dez e doze meses após o início dos tratamentos. Tanto em aplicação única de fósforo, no plantio, quanto na aplicação de doses crescentes parceladas via fertirrigação, observou-se que no primeiro ano de produção o teor foliar de fósforo de cafeeiros aumenta com aumento da lâmina de irrigação.

R E S U M OO potássio é o segundo nutriente mais exportado pela cultura da soja. Dessa forma, sua disponibilidade no solo pode influenciar tanto o rendimento da cultura, como a qualidade e composição química das sementes de soja. Este trabalho teve como objetivo avaliar o efeito da adubação potássica sobre caracteres agronómicos, teor de óleo e qualidade sanitária de sementes de soja. Os ensaios decorreram no ano agrícola 2012/2013 em dois locais distintos no Estado de Minas Gerais, Brasil. O delineamento experimental constou de um esquema em blocos casualizado, com três repetições, e tratamentos dispostos em esquema fatorial 4 x 6, com quatro cultivares (TMG 127 RR, TMG 1179 RR, BRSMG 850GRR, NA 7255 RR) e seis doses de potássio (0, 40, 80, 120, 160 e 200 kg.ha -1 ). Foram avaliados o rendimento, altura de plantas, inserção de primeira vagem, acama de plantas, teor de óleo e a sanidade de sementes. O aumento nas doses de potássio alterou a composição química das sementes e incrementou significativamente o teor de óleo; no entanto, não houve efeito para os caracteres agronómicos e o rendimento de grãos. Os níveis de patógenos nas sementes aumentaram à medida que se diminui o fornecimento de potássio para as plantas. Palavras -chave:Glycine max (L.) Merril, macronutriente, teor de óleo. A B S T R A C TPotassium is the second most exported nutrient for soybean. Thus, their availability in the soil can influence both crop yield, the quality and chemical composition of soybean seeds. The objective of this work was to evaluate the effect of potassium fertilization on agronomic traits, oil content and sanitary quality of soybean seeds. The trials took place in the agricultural year 2012/2013 in two separate locations in the state of Minas Gerais, Brazil. The experimental design consisted of a randomized block design, with three replications, and treatments arranged in a factorial scheme 4 x 6, with four cultivars (TMG 127 RR, TMG 1179 RR, BRSMG 850GRR, NA 7255 RR) and six doses potassium (0, 40, 80, 120, 160 and 200 kg ha -1 ). They evaluated the yield, plant height, first pod insertion, plants lodging, oil content and seed health. The increase in potassium levels altered the chemical composition of seeds and increased significantly oil content; however, there was no effect on the agronomic characteristics and grain yield. The contents of the seed pathogens increase as it decreases the potassium supply to the plants.

An option into guide selection strategies in soybean breeding programs is to investigate associations between the main traits studied by breeders. A question that is faced is the possible influence of genotype x environment (GE) interactions on correlations among traits. Path analysis allows, in addition to measuring correlation, a more detailed study of cause / effect relationships among traits. We measured the effect of the GE interaction in the association between agronomic traits in soybeans. The experiments were carried out during two crop seasons, in three municipalities of Minas Gerais, Brazil, using a randomized complete blocks design, with 35 treatments. We evaluated number of grains, number of pods (NP), number of grains per pod, grain yield, weight of 100 grains, lodging score, plant height, height of first pod insertion, and full maturity. The data were submitted to variance analysis and path analysis. We also calculated the sum of ranks index in three ways, considering different economic weights. The correlation between grain yield and other traits, as well as direct and indirect effects, varied in magnitude and direction, considering individual and multienvironmental analyses, demonstrating the influence of the GE interaction. For example, considering the individual analysis for Lavras ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 18 (3): gmr18099 D.R. Pereira et al. 2 in 2015/16, the correlation between grain yield and NP was-0.0534 and was not significant at the 5% level by the Mantel test, and the direct effect of NP on grain yield was 0.1717, while in the joint analysis of all environments, the correlation between these traits was 0.3674 and was significant, and the direct effect of NP on grain yield was-0.0520.The direct effect as an economic weight in the sum of rank index can be more efficient in selecting cultivars when compared to a simple correlation; this could become a useful strategy for the selection of multiple traits.

Selection indices are good for classification because they consider several evaluated traits simultaneously to identify superior cultivars with a combination of the traits of interest. Adaptability/stability methods enable determining contributions to the genotype-by-environment (G × E) interaction and the risk associated with each cultivar. This study used a univariate and multivariate strategy to identify commercial soybean cultivars that presented both precocity and good productive performance and studied the G × E interaction considering all cultivars both simultaneously and by maturation groups. The experiments were conducted in the agricultural years 2014/15 and 2015/16 in seven distinct environments in southern Minas Gerais State, Brazil, considering a combination of locations and seasons. A randomized complete block design was used, and the treatments included 35 commercial soybean cultivars. In the univariate analysis, were evaluate several traits. Selection indices were calculated considering yield, harvest index, plant height, first pod insertion height and absolute maturation. The selection strategy efficiencies were quantified using the coincidence index. Each cultivar’s contribution to the G × E interaction and associated risk were determined using the ecovalence and confidence index methods, respectively. The results showed that the NS 7000 IPRO and NS 7209 IPRO cultivars were the most productive. The NS 7000 IPRO cultivar, although obtaining a good yield, contributed greatly to the G × E interaction when considering the maturation groups. The low coincidence in ranking the strategies indicates that more than one agronomic trait should be used to classify the superior cultivars.