Álvaro Carlos Gonçalves Neto

Resistência mediada por aleloquímicos de genótipos de tomateiro à mosca-branca e ao ácaro-rajado

The objective of this work was to assess the degree of resistance to the whitefly (Bemisia argentifolii) and to the two-spotted spider mite (Tetranychus urticae) of tomato hybrids resulting from crosses between high-zingiberene (ZGB) lines and high-acylsugar (AS) lines, as compared to their parental lines and to commercial vouchers. High-AS lines, high-ZGB lines, double heterozygous (ZGB+AS) hybrids, hybrids heterozygous for ZGB and hybrids heterozygous for AS were tested. The wild accessions PI 127826 and LA-716 were used as high-ZGB and high-AS vouchers, respectively, while the genotypes Debora Max and TOM-684 were used as vouchers for low ZGB and AS. The genotypes were submitted to resistance tests to the whitefly and repellency to the spider mite. Double heterozygous (ZGB+AS) hybrids were more resistant to whiteflies than the commercial vouchers, but less resistant than the high-ZGB or the high-AS lines. Double heterozygous (ZGB+AS) hybrids were more repellent to the spider mite than the commercial vouchers, and their repellency to mites was similar to that of high-ZGB or high-AS lines. There was no synergistic effect between ZGB and AS, for both resistance to the whitefly and repellency to the two-spotted spider mite, in the double heterozygous (ZGB+AS) genotypes.

Aptidões de genótipos de batata-doce para consumo humano, produção de etanol e alimentação animal

The objective of this work was to identify agronomic aptitudes of sweet potato (Ipomoea batatas) genotypes for fresh consumption, ethanol production, and animal feed, using aptitude indices. The aptitude indices were established as the weighted means of standardized variables for 16 traits of interest, using different weights for each trait according to the evaluated aptitude. The experimental design was a completely randomized block, with two replicates and 39 sweet potato genotypes: 36 accessions of the germplasm collection of Universidade Federal de Lavras (Brazil) and three commercial cultivars (Palmas, Brazlândia-Branca e Brazlândia-Rosada). Eight genotypes were considered apt to ethanol production, 11 to animal feed, and 11 to human consumption, including the cultivars Palmas and Brazlândia-Branca. The accessions UFLA07-12, UFLA07-31, UFLA07-43, UFLA07-49, and UFLA07-53 showed aptitude for ethanol production, animal feed and human consumption. The selection index is efficient in establishing aptitudes for sweet potato genotypes.

Resistance to the South American tomato pinworm in tomato plants with high foliar acylsugar contents

A traca-do-tomateiro foi constatada pela primeira vez no Brasil em 1980 estando hoje dentre as principais pragas da tomaticultura nacional. O controle desta praga e feito principalmente por inseticidas, sendo realizada em casos extremos, ate tres pulverizacoes semanais. Acessos silvestres de tomateiro como S. pennellii LA-716 possuem resistencia a pragas, mediada pela presenca de acilacucares nos foliolos. Os objetivos deste trabalho foram obter genotipos de tomateiro com caracteristicas comerciais e altos teores foliares de acilacucares (AA), e avaliar seus niveis de resistencia a traca do tomateiro Tuta absoluta. Os genotipos foram obtidos a partir de populacoes segregantes (F2) oriundas do cruzamento entre AF-8665 (linhagem elite com baixos teores de AA) e as linhagens BPX370E-30-275-11-7, BPX370E-30-275-11-8, BPX370E-30-380-68-6 e BPX370E-30-380-68-8 (linhagens pre-comerciais com altos teores, obtidas a partir do cruzamento interespecifico S. lycopersicum x S. pennellii LA-716). Plantas F2 previamente selecionadas com base nos teores de AA foram clonadas e em seguida testadas quanto a resistencia a traca-do-tomateiro. Genotipos selecionados para altos teores de AA expressaram menor ovoposicao da traca e niveis inferiores de danos causados a planta pela infestacao do microlepidoptero do que genotipos (comerciais ou nao) com baixos teores de AA. Embora genotipos com altos teores de AA tenham sido mais resistentes a traca do que os demais, seus niveis de resistencia podem ser dependentes do background genotipico: clones BPX-410H (alto teor de AA) mostraram-se em geral ligeiramente mais resistentes do que o dos clones BPX-370G (tambem alto teor de AA). Os clones BPX-410H-01pl#281, BPX-410H-04pl#348 e BPX-410H-04pl#481 foram superiores nas avaliacoes de resistencia a traca e sao recomendados para a continuidade do programa de melhoramento.

Híbridos pré-comerciais resistentes a Tuta absoluta obtidos de linhagem de tomateiro rica em acilaçúcares

This experiment was designed to assess the agronomic potential of tomato hybrids obtained from the tomato line TOM-687, an acylsugar-rich line with confirmed resistance to an array of tomato pests. The experiment was carried out at the HortiAgro Sementes research station, in Ijaci, Minas Gerais State, Brazil. The treatments comprised 30 genotypes (5 commercial hybrid checks, 1 high acylsugar line (TOM-687), and 24 hybrids in which TOM-687 was one of the parents). Plants were trained to two stems, in a spacing of 1.30 m between rows x 0.50 m between plants within a row, totaling 15,385 plants per hectare. Nine harvests were performed between November 1st, 2008 and November 28th,2008. Traits assessed were mean fruit weight (g fruit-1) and total yield (t ha-1). All 24 hybrids with TOM-687 as a parent showed yields similar to those of the commercial check hybrids Debora Max, Bravo, Bonus, Kombat and Atyna. Four of these experimental hybrids (TEX-298, TEX-310, TEX-315 and TEX-316) were assessed for resistance to the South American tomato pinworm Tuta absoluta, and were shown to possess higher degrees of pest resistance than the current commercial hybrid checks.

Seleção de clones de batata-doce resistentes a Meloidogyne incognita raça 1

The objective of this work was to select sweetpotato (Ipomoea batatas) resistant clones to Meloidogyne incognita race 1, and to assess the efficiency of the selection method deployed, through the estimation of genetic and environmental coefficients of variation, and broad-sense heritabilities. Genotypes assessed comprised 123 sweetpotato entries altogether, including four commercial cultivars - Brazlândia Rosada, Brazlândia Roxa, Brazlândia Branca, Palmas - and 119 clones previously selected by the Universidade Federal de Lavras sweetpotato breeding program. The experimental setup was a an augmented block design, using three common treatments: the sweetpotato cultivars Brazlândia branca and Palmas, and the nematode-susceptible tomato cultivar Santa Clara. Nematode resistance levels were defined both by the nematode reproduction factor and by the nematode reproduction index relative to tomato cv. Santa Clara. The ratio between genetic and environmental coefficients of variation and the broad-sense heritability estimates were high, for both nematodes reproduction factor and reproduction index, indicating that the selection method deployed was efficient for the selection of resistant genotypes. Fifty-seven sweetpotato clones were identified as resistant to M. incognita race 1, and selected to continue in the sweetpotato breeding program.

Correlação entre caracteres e estimação de parâmetros populacionais para batata-doce

Sweetpotato cultivars currently grown were selected essentially for their use in human consumption, with little regard for their other potential uses such as ethanol production or animal feed. The objective of this work was to estimate population parameters and genotypic, phenotypic and environmental correlations associated with these traits. Thirty-nine sweetpotato genotypes from the germplasm bank of the Universidade Federal de Lavras were assayed in a randomized complete block design trial with 2 replications. The estimated genetic (CVg) and environmental (CVe) coefficients of variation, the broad sense heritabilities (ha2) and the b= CVg/CVe ratio favor selection of the majority of the traits analysed, with estimates generally higher than 9.52%, 1.44 and 79.31% for CVg, CVg/CVe and ha2, respectively. For all pairs of traits studied, the genotypic and phenotypic correlations had the same sign, and were similar in both magnitude and level of significance. In the cases where correlations were significant, the estimates of the genotypic correlations were slightly higher than those of the phenotypic correlations, and both were higher than environmental correlations as was observed between total fresh root yield x percentage of dry matter in roots, percentage of dry matter in the leaves+vines x total fresh root yield, mean root shape ratings x general root shape ratings. No genetic or phenotypic correlation was observed beetween percentage of root dry matter and measured root density. The selection and recommendation of sweet potato genotypes based on a set of these studied characteristics (depending on the segment of market to be explored), will make possible the complete use of this precious vegetable genetic resource, and its more intense adoption in national agriculture.

heterose e capacidade combinatória de linhagens de tomateiro ricas em acilaçúcares

Com o presente trabalho, objetivou-se estimar a capacidade combinatoria de linhagens de tomate ricas em acilacucares (AA) quando cruzadas com linhagens com baixo teor de acilacucares e estudar a expressao da heterose nos hibridos obtidos. O experimento foi realizado no campo da HortiAgro Sementes Ltda, localizada em Ijaci-MG. O material genetico foi constituido de seis hibridos experimentais em esquema de dialelo parcial, constituido de tres genitores masculinos (grupo I, com altos teores de acilacucares) e dois genitores femininos (grupo II, com baixos teores). Foram avaliadas as caracteristicas: massa media de fruto (g fruto-1) e producao por hectare (t ha-1). As linhagens TOM-687 e TOM-688 (ricas em AA e resistentes a pragas) apresentaram estimativas positivas dos efeitos de capacidade geral de combinacao, para massa media de frutos, e estimativas negativas, para producao, o que significa que elas contribuiram positivamente para aumento no tamanho do fruto, mas reduziram a produtividade dos hibridos. Ja a linhagem TOM-689, ao contrario das duas anteriores, contribuiu para reduzir o tamanho do fruto, mas contribuiu para aumentar a produtividade dos hibridos. Os hibridos obtidos do cruzamento de linhagens com altos teores de acilacucares mostraram-se competitivas quando comparadas a hibridos comerciais encontrados no mercado. As melhores combinacoes hibridos foram obtidas quando as linhas com altos teores de acilacucares foram cruzadas com a linhagem elite TOM-684.

Caracterização de genótipos de tomateiro resistentes a begomovírus por marcador molecular co-dominante ligado ao gene Ty-1

The objectives of this study were to evaluate tomato genotypes for begomovirus resistance and to assess SSR-47 fingerprinting patterns associated with alleles Ty-1, in hybrids of fresh-market tomato with commercial potential. Twenty-four experimental genotypes, heterozygous at Ty-1 locus, were infected with begomovirus via grafting, and showed intermediate symptoms compared to the ones identified by homozygous Ty-1/Ty-1 lines and by susceptible genotypes Ty-1+/Ty-1+, which indicates the incomplete dominance of the Ty-1 allele. These hybrids were considered to possess partial resistance to begomovirus. The experimental hybrids TEX-246, TEX-261, TEX-253, TEX-256, TEX-262, TEX-252, TEX-251 and TEX-268 combined high total yields with high mean fruit mass. The hybrids TEX-246, TEX-253, TEX-256, TEX-262 and TEX-252 showed also longer half-life for fruit firmness and were thus considered competitive with current commercial hybrids used as checks. The molecular marker SSR-47 was effective for fingerprinting of tomato genotypes bearing the resistance allele Ty-1. The graft-induced infection of begomovirus showed symptoms in the genotypes tested that are in agreement with the results of fingerprinting with the marker SSR-47.