Resumo em Inglês:

Abstract This study estimated the general and specific combining abilities and mean heterosis of tobacco lines of the varietal groups Flue-Cured Virginia (FCV) and Air-Cured Burley (BY). In addition, possible advantages and an improved strategy of using hybrids in tobacco breeding in the tropics were discussed. Ten BY and 13 FCV lines were crossed in a diallel mating design. The hybrids and parental lines were evaluated at two locations in Southern Brazil. The mean heterosis was 5.37% for FCV and zero for BY lines, although higher than 15% in some combinations. The occurrence of heterosis indicates dominance in the control of tobacco yield. Tobacco breeding programs must focus primarily on improving the performance of lines per se and then on the identification of the best hybrid by testing combinations.

Resumo em Inglês:

Abstract Hancornia speciosaGomes, a native fruit tree, plays an important socio-economic role in Brazil's traditional communities. The objective was to estimate the genetic structure of 176 individuals from eight locations in the Cerrado, Caatinga and Atlantic Forest biomes, based on six microsatellite markers. The analyzes revealed the formation of five population groups: A- Pernambuco, Paraíba and Sergipe (Atlantic Forest), B- Maranhão (Cerrado); both, var. speciosa, C- Bahia (Caatinga / Cerrado transition zone) and Ceará (Caatinga), D- Goiás (Cerrado) and E- Minas Gerais (Cerrado,) being groups C, D and E possibly var. pubescens. Most of the genetic variation is within the groups (65.61%, Fst = 0.34, p <0.001). Although group A had the highest Ho (0.66), it had a negative fixation index (f = -0.02), while the other had positive values. Our results revealed high levels of genetic diversity and provide support the development of more efficient conservation strategies for H. speciosa.

Resumo em Inglês:

Abstract In breeding for resistance to Fusarium head blight (FHB) there should be precise differentiation between QTL for resistance and those for spike architecture traits that indirectly affect disease. QTL mapping for FHB Type II resistance and spike architecture traits was carried out in a population of 80 RIL. Three QTL for FHB Type II resistance were identified respectively on chromosomes 2A, 4A and 6D, the last of which is reported here for the first time. The number of florets per spike and per spikelet was associated with FHB Type II resistance but there was not co-localization between QTL for these traits. However, QTL for number of spikelets per spike overlapped with those for FHB Type II resistance on chromosomes 2A and 6D. Spike architecture traits - notably, the number of florets per spike and per spikelet - should be considered in the design of breeding strategies to increase Type II resistance to FHB in bread wheat.

Resumo em Inglês:

Abstract Wheat blast disease is responsible for severe production losses. The disease resistance associated with the 2NS/2AS translocation is effective, but its level can be variable. In this study, we evaluated the presence of 2NS/2AS translocation in 310 advanced breeding lines from six crosses (Caninde 2/Milan, Milan/Caninde 2, Maringa/Milan, Milan/Maringa, Ciano79/Milan and Milan/Ciano79), and also studied their wheat blast reaction in the field to three virulent pathogen strains (P13-009, P14-031 and P14-039) collected in Paraguay. Advanced lines of two crosses (Caninde 2/Milan and Milan/Caninde 2) yielded the highest number of blast-resistant entries without 2NS/2AS translocation. Earlier studies have shown Caninde 2 to be a moderately susceptible line, which in combination with Milan, is probably adding non-2NS/2AS type resistance to these crosses. Our result indicates that such a resistance is based on several additive factors derived from multiple sources, which need to be explored further and also used to develop more durable wheat blast-resistant germplasm in the future.

Resumo em Inglês:

Abstract The objective of this study was to establish classification ranges for genetic and additive genetic coefficients of variation, as well as for broad and narrow sense heritability, as a function of growth and wood quality traits for Eucalyptus spp. We conducted statistical analyses to determine differences in this classification the types of coefficients used. The selected studies that met the inclusion criteria, 58 presented genetic variation coefficients (448 data points) and 53 presented heritability coefficients (423 data points). To descriptive statistics and the Shapiro-Wilk test, we confirmed that it was necessary to separate coefficients and traits into groups. Inconsistencies for growth traits were observed, confirming the influence of experimental error, indirect estimation methods, and environmental effects on coefficient estimates. We recommend the use of the classification tables included in this literature review to interpret results in studies so as to standardize the classification of coefficients of genetic variation and heritability.

Resumo em Inglês:

Abstract To meet the demands of the production chain, breeding programs need to reduce the time for selection and development of higher yielding maize genotypes. This involves application of new strategies, such as the use of the doubled haploid lines. We evaluated the use of stomatal area and density in distinguishing doubled haploids (DH) from false positive (FP) plants derived from nine tropical source populations. We selected four DH plants and two FP plants for identification of DH through leaf anatomy in the populations, in each group. Data on stomatal area and density were considered in a completely randomized model in a factorial scheme (populations and genotypes) and analyzed by restricted maximum likelihood. There were statistically significant effects of populations and genotypes for both traits. For stomatal density, the population by genotype interaction was not verified. Stomatal density proved to be efficient for distinguishing DH and FP for use in selection of doubled haploids.

Resumo em Inglês:

Abstract The conservation of plant genetic resources is fundamental for the development of agriculture. The development of efficient cryopreservation protocols has become an effective tool to preserve cells, tissues and organs of different plant species. We sought here to develop an efficient method of cryopreservation of Eucalyptus grandis employing the V cryo-plate technique. This experiment examined the exposure of shoot tips to three different cryoprotectants (PVS2, PVS3, and PVS4). The cryoprotectants PVS2 and PVS4 proved to be more efficient among the cryoprotectants tested, as 44.4% of the shoot tips immersed in those solutions survived, and 31.1% generated new shoots. Ethylene glycol was found to be a key compound for the successful cryopreservation of shoot tips, in light of its low toxicity as compared to other cryoprotective compounds. Thus, the methodology developed here represents an effective method for the conservation of E. grandis germplasm through cryopreservation and the use of the V cryo-plate technique.

Resumo em Inglês:

Abstract Tree breeders use traits of economic interest as productivity, stem form and wood quality, to select individuals for advanced generations. We determined the genetic control of growth volume, tree height and diameter, stem form and wood resistance, and calculated a selection index for Pinus maximinoi and P. tecunumanii, selected individuals were used to establish a seedling seed orchard (SSO). The largest genetic gain obtained in SSO for P. maximinoi was 21.48% for volume, while for P. tecunumanii it was 21.87% for stem form. There is enough genetic variability for genetic gain in future generations in tests of P. maximinoi and P. tecunumanii progenies. The selection index provided satisfactory total genetic gains for several traits, being more recommended than the BLUP method in order to support the selection and ranking of superior genetic materials in the progeny tests with greater probability of retaining favorable alleles over generations.

Resumo em Inglês:

Abstract We aimed to measure the efficiency of visual selection of plant vigor for green biomass production of U. ruziziensis using single- and multitrait approaches to maximize the predictive accuracy of the genetic value. The green biomass production and plant vigor of 254 U. ruziziensis clones were measured over nine evaluation cuttings to determine the efficiency of these approaches for production improvement. Individual and multicutting analyses were performed under single-trait and multitrait approaches using mixed models. The efficiency of visual selection was assessed by measuring plant vigor based on direct and indirect genetic gains. Plant vigor showed a high genetic association with green biomass and could be selected for production, especially in the initial phases of breeding programs. The multitrait approach was superior to the single-trait approach in predicting the genetic value of the clones, and it can be used in U. ruziziensis breeding programs.

Resumo em Inglês:

Abstract ‘BRMGS Camaleão’ is a mungbean cultivar with large, shiny, green seeds released for the state of Minas Gerais, Brazil. It was developed by the Asian Vegetable Research and Development Center as line VC 6148-B-16. In seven trials established in the Zona da Mata region, it had an average yield of 1493 kg ha-1 and 1000-seed weight of 68-78 g.

Resumo em Inglês:

Abstract: The cultivar BRS 420 has superior starch yields in early and late harvest, moderate resistance to the main diseases of the crop, adaptation to mechanized planting and to the no-till system, as well as rapid formation of soil cover (which assists in weed control). It represents an alternative for cassava growers in Paraná and Mato Grosso do Sul.

Resumo em Inglês:

Abstract NDLH 2051-1 has a mean seed cotton yield potential of 1590 kg ha-1 and has been singled out for commercial cultivation in the south and central zones of India by the Regional Agricultural Research Station, Nandyal, India. This cultivar represents an essential contribution to sustainable cotton production in India.

Resumo em Inglês:

Abstract ‘Caviano’ is a black bean cultivar recommended for Santa Catarina, for being highly adaptable to the main grain-producing regions of the state (mean grain yield 2315 kg ha-1). Compared to previously released cultivars, Caviano has a larger root system and desirable characteristics for mechanical harvesting.