Resumen en Inglés:

Abstract Yellow passion fruit (Passiflora edulis Sims) yield and longevity have been drastically reduced by bacterial spot (Xanthomonas axonopodis pv. passiflorae - Xap) and passion fruit woodiness disease (PWD) (Cowpea aphid-borne mosaic virus - CABMV). This study was aimed at evaluating the reaction of 11 genotypes of yellow passion fruit, based on the reaction of their progenies, to both mechanically inoculated Xap and CABMV, under greenhouse conditions. There was a progressive increase in bacterial spot and PWD severity with time. BRS Gigante Amarelo, MAR20#12, and MAR20#34 were selected as the progenies with lowest bacterial spot severity and disease progress over time. MAR20#2005, EC-L-7, UnB2015-1, and EC-3-0 presented the lowest PWD severity and disease progress over time. These progenies, along with individual plants from other progenies in which disease severity was significantly low until the last evaluation, will be cloned and tested again for Xap and CABMV, including other isolates.

Resumen en Inglés:

Abstract The present work aimed to estimate the adaptability and stability of new papaya hybrids. The experiments were carried out at the company Caliman Agrícola S/A, in the municipalities of Linhares-ES and Pureza-RN, with seven hybrids from inbred parents of the groups ‘Solo’ and ‘Formosa’ and three controls (‘Golden’, ‘Calimosa’, and ‘Tainung 01’). The experiment consisted of a randomized block design with four replications and ten plants per plot. The variables mean fruit weight (MFW), number of commercial fruits (NCF), and production (PROD) were measured at 270, 360, 450, and 540 days after planting. Afterward, the adaptability and stability of the hybrids were estimated using the Lin and Binns, Eberhart and Russell, and Mixed Models. MFW was less affected by the evaluation periods and showed high behavior predictability. The hybrids UC10, UC12, UC14, UC15, and UC16 were the most adapted and predictable and can be recommended for the regions where the experiment took place.

Resumen en Inglés:

Abstract In breeding of sweet sorghum hybrids, non-additive genetic effects are important in phenotypic expression of the traits of interest. The aim of this study was to evaluate the general combining ability (GCA) of sweet sorghum lines and the specific combining ability (SCA) of the hybrids for agronomic and technological traits. Five fertility restorer lines, four male-sterile lines, and their hybrids from partial diallel crosses were evaluated in experiments laid out in a 5 x 6 triple rectangular lattice design in the municipalities of Lavras, MG and Sete Lagoas, MG, Brazil. Diallel analysis was performed using the Griffing model adapted to partial diallel crosses. There was a significant effect of GCA and SCA for most of the traits evaluated, indicating the participation of additive or dominant genes in inheritance. The restorer lines CMSX508, BRS 511, CMSXS643, and CMSXS646 show potential for use as parents in sorghum breeding programs.

Resumen en Inglés:

Abstract The objective was to determine the predominant genetic inheritance in the trait root distribution in common bean and define the selection strategy. An experiment involving 40 genetic constitutions (segregating and fixed populations), was developed during the agricultural years 2014/15 and 2015/16. The experiment was arranged in a Federer's augmented block design with 3 replicates. The root distribution was evaluated by Bohm method. Estimates of mean contrasts between the F4 progenies and their parents did not reveal any significant differences in any comparison. The generations F5 and F6 presented the same behavior. The distribution of the component of the additive genetic variance was similarly conducted for the segregating generations. Thus, since the predominant inheritance of the root distribution is additive, the selection of this trait is recommended to be performed at the end of the breeding program.

Resumen en Inglés:

Abstract Breeding new maize varieties that take up more N from the soil and increase N fixation is a crucial source of combined nitrogen in agricultural systems. Thus, this study aimed to select superior maize parental lines efficient in the use of nitrogen and Azospirillum brasilense. Three experiments were conducted in two agricultural seasons aiming to allocate all diallel hybrids in three different nitrogen conditions. The experiments were performed in a RCB design with two replications, and the diallel was analyzed using the mixed model approach. The general combining ability and Azospirillum use efficiency were applied to select the best parental line. The most promising hybrid combinations were “I-08 x II-06”, “I-02 x II-04”, and “I-01 x II-02”. Parents involved were selected for the development of hybrids. Parents I-01, I-02, I-08, II-01, II-02, II-04, II-05, and II-06 were selected to explore the basic population in the A. brasilense-use efficiency breeding program.

Resumen en Inglés:

Abstract Asian soybean rust (ASR) is one of the most serious diseases for soybean crops, and it can be responsible for severe yield reduction. Due to the low durability of vertical resistance, studies on horizontal resistance are important for breeding programs. The objective of this study was to identify quantitative trait loci (QTLs) related to ASR horizontal resistance. A genetic linkage map with 26 groups was generated for simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers from 163 recombinant inbred lines (RILs). We found 13 QTLs related to 12 traits, including eight directly related to plant resistance. Furthermore, two QTLs controlling more than one trait were observed: one was related to agronomical traits, and another was related to a similar region of the Rpp3 locus associated with the number of uredinia and sporulation levels. These results will be useful for breeding programs to generate cultivars resistant to ASR.

Resumen en Inglés:

Abstract The aim of this study was to evaluate the genetic diversity of the wheat germplasm using high-density genotyping with SNP markers. A set of 211 wheat varieties genotyped with 35,142 SNP markers were used in the experiment. Genetic distances ranged from 0.013 to 0.471, with the highest frequency of distances varying between 0.31 and 0.40. In the cluster analysis by the UPGMA method, 81% of the varieties were clustered in three groups. Genetic variability in the Brazilian wheat germplasm has remained constant for over 70 years. Mean genetic distances among the varieties developed in each decade ranged from 0.33 to 0.34. A trend of genetic distance between genotypes from different eras has been observed over time as a result of breeding. Results described in this study can help Brazilian wheat breeders to manage more adequately genetic variability in the Brazilian wheat germplasm.

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Abstract Due to the great economic importance of coconut palm in Brazil and the development of a coconut breeding program intended to produce intravarietal hybrids, the present work aimed to ease the production of hybrids with the same morphological heritage. DNA was extracted from leaf samples of 13 dwarf coconut populations from Brazil, and PCR amplification was performed using 21 previously selected microsatellites. Furthermore, this study selected nine microsatellite markers with the potential to identify Green Dwarf x Yellow Dwarf hybrids and 16 microsatellites with the potential to identify Red Dwarf x Yellow Dwarf hybrids. In conclusion, SSR marker based on DNA Fingerprinting allowed the accurate identification of legitimate intravarietal hybrids since, for those crosses, the methodology of identification based on seedling color is not a viable alternative.

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Abstract Studies highlight the hypocotyl diameter (HD) as an effective indicator of plant architecture (PA). Here, we estimated the genetic gain based on HD to improve PA. Twenty populations of cycles zero (C0) and one (C1), both in the F4 generation, were evaluated for PA, grain yield (GY) and HD. Plants with thickest HD in C0 were intercrossed in a circulant diallel mating design. In cycle C1, an estimated genetic gain of 4.93% was achieved for PA and 4.95% for HD. The populations with the highest probability of breeding lines with a thicker HD belong to cycle C1, and this selection strategy did not alter the GY of the populations of this cycle. Thus, indirect selection based on HD is promising for breeding for common bean PA by recurrent mass selection.

Resumen en Inglés:

Abstract Brazil is the largest sugarcane producer in the world and, the main varieties grown in Brazil, known as RB cultivars, were developed by the Interinstitutional Network for the Development of the Sugar and Alcohol Sector (RIDESA) and are used in 58.9% of the planted area in Brazil. These varieties were obtained through intercrosses between genotypes from the Serra do Ouro germplasm bank and successive crosses with related genotypes may have increased the level of genetic similarity. The aim of the present study was to analyze the genetic base of the Serra do Ouro germplasm bank over the past decades using microsatellite molecular markers. The genetic similarity among varieties using all the markers ranged from 0.166 to 0.823, and regression analysis showed an increase in genetic similarity in the 1970s; however, a narrowing of the genetic base over the last five decades was not observed.

Resumen en Inglés:

Abstract Paspalum notatum is a polymorphic species with two accepted varieties, according to the ploidy level. The ploidy level is closely related to the reproductive mode of this species. Usually, diploid cytotypes have sexual reproduction, and tetraploid cytotypes have an apomictic reproduction. Apomixis limits genetic recombination, hindering the development of new cultivars. The identification of sexual plants represents many possibilities in breeding programs. This study aimed to analyze the chromosome number in P. notatum accessions under agronomic evaluation. Ploidy level was determined in 25 accessions. Two ploidy levels were detected, resulting in 21 tetraploid and four diploid accessions. The four diploid accessions originate from Argentina and Uruguay, in a region close to the origin of Pensacola, which is a diploid sexual cultivar of P. notatum. These new diploid accessions may be useful in the development of breeding programs of Paspalum species.

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Abstract UENF Rioparaíba common bean cultivar from the black commercial group has a high grain yield (2351 kg ha-1), stability, and wide adaptation to the Northern and Northwestern regions of the state of Rio de Janeiro. The new cultivar contains 20.7% crude protein and has a mass of 1000 seeds equals to 256.8 g.

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Abstract BRS Sublime is a common bean cultivar with carioca grains, high nutritional grain quality, and high yield potential (4667 kg ha-1). It has a normal cycle, upright growth, low loss rates in the mechanical harvest, and is recommended for planting in 19 Brazilian states, in the three main common bean cultivation regions. It is the first cultivar developed in the world with angular leaf spot resistance.

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Abstract The early-maturing irrigated rice cultivar BRS A702 CL was developed by Embrapa in partnership with BASF for the Clearfield Production System of irrigated rice in the tropical region of Brazil. In the states of Tocantins and Roraima, BRS A702 CL produces a mean yield of 7,650 kg ha-1.

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Abstract The sweet cassava cultivars BRS 396, BRS 397, BRS 398 and BRS 399, were selected through 27 participatory tests conducted at Distrito Federal, Brazil. Their agronomic performance and their high level of acceptance among producers qualify them as a new crop option for cultivation in the region.

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Abstract IRGA 431 CL is an early rice variety, and its main characteristic is the resistance to Imidazolinones herbicides. The variety stands out for its excellent plant architecture, strong stems, high yield potential, good grain quality, and resistance to blast and high levels of toxic iron in the soil. It is recommended for exploitation in the rice fields of Rio Grande do Sul, Brazil.

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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.