Adérico Júnior Badaró Pimentel

Eficiência de fungicidas no controle da brusone em trigo

Wheat blast, caused by the fungus Pyricularia grisea, constitutes one of the major obstacles to the expansion of wheat production in Central Brazil. The aim of this study was to evaluate the efficiency of fungicides in the control of wheat blast. Three fungicides with different active ingredients and combined with four wheat genotypes were used. Two applications of the commercial product were performed in stages 45 and 65 of the scale of Zadoks et al. Artificial inoculation with P. grisea spores was done in stages 58-60 of the above-mentioned scale. The area under the disease progress curve (AUDPC), the severity on flag leaves (SEVFL) and the severity on spikes (SEVEsp) were determined, and grain yield (GY) was quantified. At the end of the experiment, different analyzed parameters were subjected to Pearsons correlation analysis. The fungicides epoxiconazole+pyraclostrobin and tebuconazole+trifloxystrobin provided the lowest AUDPC for the genotypes VI 03061, VI 07505 and BRS 254. There was no difference for SEVFL among genotypes in the presence of fungicides. The genotypes VI 98053 and VI 07505 showed the lowest SEVFL in the absence of fungicide. Tebuconazole+trifloxystrobin provided higher GY and lower SEVEsp. The disease severity on the ears was greater than on flag leaves. Control of wheat blast by means of fungicide application was effective for flag leaves but not for ears.

Estimação de parâmetros genéticos e predição de valor genético aditivo de trigo utilizando modelos mistos

The objective of this work was to estimate the genetic parameters and to predict the genotypic value of populations and individuals from wheat segregating populations, using the methodology of mixed models (restricted maximum likelihood/best linear unbiased prediction, REML/BLUP). Thirty-six wheat segregating populations and four controls were evaluated in the F3 generation, in a randomized complete block design, with individual information taken from within the plots. The evaluated traits were: grain yield, harvest index, number of tillers, and plant height. Genetic variability between populations was observed for all evaluated traits. The mean heritability varied from 39.15 to 92.78%, and accuracy varied from 62.57 to 96.32% in the selection of populations. The narrow-sense individual heritability was low within populations for all traits. The accuracy for individual selection had a moderate value for plant height, and low values for the other traits. Individual heritability contributes to a greater gain for the traits plant height and harvest index with the use of individual BLUP, in comparison to population BLUP. The segregating populations Embrapa22/BRS207, Embrapa22/VI98053, Embrapa22/IVI01041, BRS254/BRS207, BRS254/VI98053, BRS254/UFVT1Pioneiro, and BRS264/BRS207 stand out with high additive genetic value, for two or more traits.

Urease inhibitor (NBPT) and efficiency of single or split application of urea in wheat crop

O NBPT (N-(n-butil) tiofosforico triamida) e uma substância inibidora da urease, que se vem apresentando como das mais promissoras para a maximizacao do uso do nitrogenio da ureia em sistemas agricolas. O objetivo deste estudo foi avaliar o desempenho produtivo do trigo irrigado, submetido a fertilizacao com ureia ou ureia+NBPT aplicadas em dose unica ou parcelada. O experimento foi conduzido, de junho a outubro de 2006, em Vicosa-MG, Brasil. Seguiu-se o esquema fatorial 2×2, em que a ureia ou ureia+NBPT foram combinadas com duas formas de aplicacao: dose total na semeadura (60kg ha-1) ou parcelada (20kg ha-1 na semeadura + 40kg ha-1, em cobertura, no perfilhamento). O delineamento experimental foi o de blocos ao acaso com dez repeticoes. Conclui-se que o parcelamento da fertilizacao nitrogenada nao promove incremento de produtividade do trigo, sob as condicoes de cultivo empregadas; o uso de inibidor de urease aumenta a produtividade da cultura do trigo, quando a ureia e aplicada, em cobertura, durante o perfilhamento, mas, seu uso nao promove aumento da produtividade quando a ureia e aplicada no sulco, durante a semeadura.

Breeding for Heat-Stress Tolerance

Heat stress is one of the main abiotic stresses that affect the production of various crops in many parts of the world. High temperatures alter several metabolic processes reducing photosynthesis activity that results mainly in grain yield losses. In this context, identifying heat-stress tolerant genotypes with high yield potential could contribute to increasing food production. This chapter deals with aspects of breeding for heat-stress tolerance. First, heat stress and the tolerance mechanisms are characterized along with the main characteristics associated with heat stress, such as cell membrane thermal stability, canopy temperature depression, and some morphological characteristics. It then presents genetic control and selection environments for heat-stress tolerance, breeding methods, and selection strategies. The chapter ends with information on the use of biotechnological tools applied to breeding for heat-stress tolerance.

Comparação de métodos de seleção de genitores e populações segregantes aplicados ao melhoramento de trigo

The methods used for selecting crosses in one crop species are not necessarily appropriate for others. The present study aimed to evaluate the application of diallel analysis, genetic diversity, parental average, and the Jinks and Pooni method for the selection of parents and superior segregating populations for the grain yield character in wheat. Thus, two experiments were conducted and the treatments were arranged in lattice (experiment I) and randomized blocks with individual information within the plot (experiment II). Twelve parental individuals and 36 segregating populations in the F 3 generation resulting from the crossing of these parents in a partial diallel arrangement were evaluated. The application of the evaluated methodologies led to distinct results. The parental average and genetic diversity alone are not efficient prediction methods. The methodology of Jinks and Pooni presents practical limitation because it is not adequate for wheat crop system. Among the evaluated methodologies, diallel analysis is the most promising method for the identification of parents and superior segregating populations.

Análise dialélica parcial em gerações avançadas para seleção de populações segregantes de trigo

The objective of this work was to estimate the effects of general and specific combining ability of wheat parental lines in advanced generations, and to select superior segregating populations. Twelve parental lines and their 36 populations in F2 and F3 generations, obtained in a partial diallel arrangement, were evaluated for grain yield. The experimental design used was a 7x7 simple lattice with two replicates, plus a treatment to complete the lattice. The effect of general combining ability was significant in both generations. There was high correlation (0.83) of the effects of general combining ability between generations, but inexpressive influence of the effects of generations and years were observed on the classification of crossings. The populations derived from the crossings between the parental lines BRS 254, BRS 264, and IAC 364 (Tucurui III) and the parental lines MGS 1 Alianca, VI 98053, and UFVT 1 Pioneiro show the greatest potential for obtaining superior lines for grain yield. The use of the partial diallel analysis in advanced generations is promising for wheat breeding programs through hybridization.

Diversidade genética em cultivares de arroz e correlações entre caracteres agronômicos

The objective of this study was to estimate the genotypic correlation between traits and study the genetic diversity of the most cultivated rice cultivars between 1950 and 2001. Two field experiments were conducted at the experimental fields known as Airport and Agronomy, both belong to the Federal University of Vicosa, in Vicosa, MG. The experiments were arranged in a randomized block design with three replications and 25 cultivars. Data on grain yield, plant height, days to flowering, initial stand, final stand, useful tillering, grains per panicle, percentage of sterile spikelets or ears per panicle, and grain weight were collected and analyzed. It was verified high genotypic correlations for most trait pairs. The traits with strongest influence on yield were grains per panicle, percentage of sterile grains and grain weight. The cultivars Guarani and Bico Ganga were the most genetically divergent and cultivars Amarelao and IAC 25 the most similar.

Protein Profile and Molecular Markers Related to the Baking Quality of Brazilian Wheat Cultivars

To carry out wheat breeding programs, proteins were identified and quantified (through sodium dodecyl sulfate polyacrylamide gel electrophoresis [SDS-PAGE] and size-exclusion high-performance liquid chromatography [SE-HPLC]) and six allele-specific markers were tested on 45 Brazilian cultivars. A microscale baking test was applied to associate analytical and genetic responses with baking quality. The results suggested a prevalence of the subunits 2* and 1 in chromosome 1A; 7+8, 7+9, and 17+18 in 1B; and 5+10 in 1D; absence of 1BL/1RS translocation in 62.2% of the genotypes; and presence of Pinb-D1b and Glu-A3d in 8.9% of the genotypes. The average SE-HPLC values were 37.50 and 45.42% for polymeric protein in total protein (PPP) and unextractable polymeric protein (UPP), respectively, and 1.29 for the gliadin-to-glutenin (GLI/GLU) ratio, with significant variation among the genotypes (P ≤ 0.05). The baking test also showed a significant difference (P ≤ 0.05) between the cultivars under the same conditions....