Hugo Cesar Rodrigues Moreira Catão

Qualidade física, fisiológica e sanitária de sementes de milho crioulo produzidas no norte de Minas Gerais

The objective of this research was to evaluate the physical, physiological and sanitary quality of corn seeds of 17 maize varieties (landraces) before and after storage in PET bottles. The seeds were submitted to the following tests: physical purity, retention on sieves, weight of 1000 seeds, germination, seed moisture content, emergence in flowerbed, infested seed exam and seed health (deep-freezing method). Germination and emergence velocity index were determined. Maize landraces seeds of different varieties presented a great percentage of physical purity and germination, which were over the minimum standards values required for commercialization of corn seeds (98 and 85%, respectively), even after storage. Seed moisture content remained below 13% before and after storage, standing out the potential of Nothern Minas Gerais for production and conservation of high-quality seeds. Three varieties presented infestation higher than the maximum values accepted for corn seeds commercialization (3%), indicating the need of better pests control during storage. Samples of three varieties have not reached satisfy standard values of retention on the same sieve (94%), indicating the need of better standardization on size classification of some seed lots.

Incidência e viabilidade de sementes crioulas de milho naturalmente infestadas com fungos em pré e pós-armazenamento

Objetivou-se com este trabalho avaliar a qualidade sanitaria e fisiologica de quatorze variedades de sementes de milho crioulas em pre e pos-armazenamento em embalagens de polietileno tereftalato (PET). Houve efeito das variedades e das epocas de avaliacoes sobre a incidencia de fungos e germinacao. Dentre a micobiota observada, Fusarium moniliforme (88%), Penicillium spp. (6,9%) e Aspergillus spp. (2,1%) tiveram a maior porcentagem de incidencia. Apos o armazenamento, houve decrescimo de F. moniliforme (69%) e aumento de Penicillium spp. (35%) e Aspergillus spp. (22%). A incidencia desses fungos nao comprometeu a qualidade fisiologica das sementes, que apresentaram elevadas porcentagens de vigor e germinacao.

Correlations among methods to estimate lipid reserves of second-stage juveniles and its relationships with infectivity and reproduction of Meloidogyne incognita

We studied the correlations between the processes used to estimate the body lipid of second-stage juveniles (J2) of Meloidogyne exigua and M. incognita, and the infectivity and reproduction of the M. incognita J2. The lipids were quantified by image analysis of the area stained red with Oil Red O dye and by the dark area of the non-stained J2. The content of neutral lipids of stained J2 of M. exigua and M. incognita correlated positively to the lipid index, body mass lipid and the dark area of J2. The period of incubation of J2 decreased the neutral lipids content and correlated significantly with the reductions of infectivity and reproduction. The period of 6 days incubation of M. incognita resulted in losses of more than 50% of the neutral lipid content, representing the threshold period for infectivity on tomato, whereas, for reproduction, the threshold was 3 days incubation.

POTENCIAL PRODUTIVO DE GENÓTIPOS DE TOMATEIRO DO GRUPO CEREJA DIANTE À INFECÇÃO POR Alternaria tomatophila

Early blight (caused by Alternaria tomatophila) is a major disease of tomato with no resistant cultivars. Thus, it is necessary to identify sources of resistance and productive genotypes for the development of new cultivars. Therefore, this study aimed to evaluate the productive potential of cherry tomato genotypes grown in the summer / fall, the severity of early blight on leaves and the incidence of disease in fruits. The treatments consisted of Carolina tomato genotypes, Cereja Vermelho, CH 152 and CLN1561A. The experimental design consisted of randomized blocks with six replications, and the experimental plot had 16 plants. The following characteristics were evaluated: area under the disease progress curve (AUDPC), average number of microinjuries on the fruits (MF), average number of fruits per bunch (NFC), average number of bunches per plant (NCP), average number of fruits per plant (NFP), average yield, number of fruits with incidence of early blight per plant (NFI) and the severity of early blight in leaves (%). The cherry tomato genotype CH152 showed tolerance to early blight with a smaller area under the disease progress curve, lower severity and fruits with incidence of A. tomatophila were not observed in this genotype. The CH152 had the highest number of fruits per bunch, greater number of bunches per plant, higher number of fruits per plant and higher productivity. This line has great potential of being integrated into breeding programs.

Health quality and germination of Butia capitata seeds treated with bactericide and fungicide

A propagacao do coquinho-azedo (Butia capitata) e limitada devido a dormencia e a alta incidencia de fungos em suas sementes. O objetivo deste trabalho foi avaliar o efeito do tratamento de sementes de coquinho-azedo com diferentes concentracoes de bactericida e/ou fungicida na incidencia de fungos e na germinacao das sementes. Para isto, sementes de coquinho-azedo foram imersas em quatro doses do bactericida kasugamicina (0, 1.5, 3.0 e 4.5 mL/L) e/ou em quatro concentracoes do fungicida carbendazim + thiram (0, 2.92, 5.84 e 8.75 mL/Kg), totalizando 16 tratamentos. Apos o tratamento, retirou-se o operculo das sementes, as quais foram colocadas em bandejas contendo areia autoclavada, revestidas com filme plastico transparente, e mantidas em viveiro. No teste de germinacao, os tratamentos foram distribuidos em delineamento de blocos casualizados em esquema fatorial 4 x 4 (doses do bactericida e doses do fungicida), com 4 repeticoes de 50 sementes por parcela. Para o teste de sanidade foi empregado o metodo do “Blotter test” em delineamento inteiramente casualizado utilizando 20 repeticoes com 10 sementes. A qualidade sanitaria e a germinacao foram avaliadas 15 e 40 dias apos o tratamento das sementes, respectivamente. Nao houve interacao entre o bactericida e o fungicida sobre a germinacao e o controle dos fungos associados as sementes. Porem, houve efeito das concentracoes de fungicida sobre os parâmetros avaliados. Observou-se correlacao negativa entre as concentracoes do fungicida carbendazim + thiram e a incidencia fungica e correlacao positiva entre as concentracoes do fungicida e a germinacao das sementes. Portanto, o tratamento fungicida reduz a incidencia fungica e propicia melhor germinacao das sementes do coquinho-azedo.