Maria do Carmo Lana Braccini

Avaliação da qualidade fisiológica de sementes de soja, após o processo de hidratação-desidratação e envelhecimento acelerado

A work was carried out with the purpose of evaluating the physiological quality of osmoconditioned soybean (Glycine max (L.) Merrill) seeds of UFV-10, IAC-8 and Doko RC varieties, in terms of response to stress induced by the accelerated aging test. Seeds were osmoconditioned in PEG 6000, with an osmotic potential of -0.8 MPa and 20 o C of temperature, for four days. After that, seeds were dried back to the initial moisture content and submitted to the accelerated aging test for the following periods: 0, 24, 48 and 72 hours. Two controls were used: untreated seeds and seeds soaked in water. After several determined accelerated aging periods, seeds were evaluated by the standard germination test, seedling length and dry biomass of seedlings. In greenhouse the speed of emergence-index and the final emergence in sand seedbed were determined. Soybean seeds hydration-dehydration treatment in PEG 6000 solution improved seed performance in relation to germination and vigor. The extent of the accelerated aging period affected seed performance in all parameters evaluated. However, PEG 6000 treatment was satisfactory in maintaining the seed quality during the accelerated aging periods. The soybean seed water soaking affected negatively the physiological seed quality. The soybean varieties showed differential response to the hydration-dehydration treatments and to the accelerated aging periods.

Tolerância de genótipos de cafeeiro ao alumínio em solução nutritiva. I. Crescimento e desenvolvimento da parte aérea e sistema radicular

An experiment was carried out in January of 1994, in the greenhouse of the Crop Science Department of the Universidade Federal de Vicosa, located in the Zona da Mata, State of Minas Gerais, Brazil (651 meter mean altitude) to evaluate the effect of aluminum on growth and development of nine coffee genotypes. Coffee plants with two pairs of fully expanded leaves were submitted to 0 and 0.296 mmol L-1 of aluminum in nutrient solution with pH 4.0 for 115 days. After this period, the plants were harvested and separated in higher and lower leaves, first pair of fully expanded leaves, stems, and roots. These plant parts were dried and evaluated for dry matter production. In addition, the following variables were evaluated: plant height, main root length, lateral root number, and leaf area of the first pair of fully expanded leaves. The aluminum inhibited shoot and root growth, with the latter showing typical symptoms of aluminum toxicity. Root dry matter reduction in presence of aluminum in the nutrient solution was the characteristic which best differentiated the genotypes. There was a reduction in the length of the main root, plant height and leaf area, and increase of lateral root number in response to increase of aluminum concentration. The evaluated characteristics allowed the differentiation of the genotypes into four groups or classes: tolerant (UFV 1359, UFV 2149), moderately tolerant (UFV 2145, UFV 2877 e UFV 2163), moderately sensitive (UFV 3880) and sensitive (UFV 2147, UFV 2198, UFV 2237).

Sowing seasons and quality of soybean seeds

Considering the difficulties of producing high quality soybean [Glycine max (L.) Merrill] seeds during the traditional cropping period in some areas of the State of Parana, Brazil, a research project was carried out with the objective of evaluating the influence of sowing dates on the physiological and sanitary quality of seeds, during the 1998/99 and 1999/00 cropping seasons, in Maringa, PR, Brazil. The experiment consisted of five cultivar competition assays, arranged in a completely randomized block design, with each assay sown at different dates (10/15, 10/30, 11/15, 11/30 and 12/15) for each cropping season. The evaluated cultivars were BRS 132 (early), BRS 133 (semi-early), BR 16 (semi-early), BRS 134 (intermediate) and FT- Estrela (late). Seeds obtained at the sowing dates were evaluated in the laboratory by germination, accelerated aging, and health tests. Sowing in November resulted in seeds with superior physiological and health quality. Cultivar BRS 133 showed the greatest stability in seed production with better quality for the different sowing dates. Cultivars BRS 134 and BRS 133, which were sown during the period from 10/15 to 11/30, produced seeds that had higher percentages of normal seedlings in the germination and accelerated aging tests. Advancing or delaying sowing dates had adverse effects on soybean seed production with regard to their sanitary quality.

Tolerância de genótipos de cafeeiro ao alumínio em solução nutritiva. II. Teores de P, Ca e Al e eficiência ao P e Ca

An experiment was carried out in January of 1994 in the greenhouse at the Crop Science Department of the Universidade Federal de Vicosa, State of Minas Gerais, Brazil. The objective of this experiment was to evaluate the effecets of aluminum on P, Ca and Al concentrations in the plants and on the P and Ca efficiencies of utilization by nine coffee genotypes. Plants were grown with 0 and 0.296 mmol L-1 of aluminum in nutrient solution, in pH 4.0, for 115 days. After this period, plants were separated in higher leaves, lower leaves, first pair of completely expanded leaves, stem and roots to evaluate dry matter yield and phosphorus, calcium and aluminum concentrations in plant parts. Aluminum tolerance was associated with lower root phosphorus accumulation, lower reduction of phosphorus translocation to shoot, lower reduction of calcium uptake and higher phosphorus and calcium use efficiency. A large accumulation of aluminum in the roots was observed, reducing the Al transport to shoot, for all coffee genotypes.

Crescimento da planta e coloração das raízes com hematoxilina como critérios de avaliação de genótipos de café quanto à tolerância à toxidez de alumínio

A selecao de plantas tolerantes ao Al e uma alternativa para solos que apresentam Al em niveis toxicos. Neste contexto, vinte e cinco genotipos de cafe foram estudados quanto a tolerância ao Al avaliada pela inibicao no crescimento da parte aerea e das raizes e pelo teste de coloracao das raizes com hematoxilina. Avaliou-se, tambem, a alocacao do Al nas pontas das raizes. Apos 35 e 75 dias de cultivo em solucao nutritiva, na ausencia ou presenca de Al, foram avaliados o comprimento da raiz principal e, aos 80 dias, a producao de biomassa seca da parte aerea e das raizes. Os resultados expressos em percentagem de inibicao causada pelo Al foram analisados pela tecnica multivariada, e os genotipos foram separados em classes: tolerante, intermediaria e sensivel. O teste de coloracao com hematoxilina foi realizado apos 80 dias de cultivo em solucao nutritiva, e os genotipos foram avaliados de acordo com a intensidade de coloracao da ponta da raiz. Apenas tres genotipos foram tolerantes ao Al e seis foram sensiveis, enquanto a maioria deles pertenceu a classe de tolerância intermediaria. O teste de coloracao com hematoxilina nao permitiu a adequada diferenciacao dos genotipos quanto a tolerância ao aluminio. Em cortes transversais das pontas das raizes do genotipo mais tolerante, observou-se a localizacao do aluminio apenas nas celulas epidermicas, enquanto, no genotipo de tolerância intermediaria, o Al localizou-se nas celulas epidermicas e em varias camadas de celulas do cortex.

Incidência de microorganismos em sementes de café robusta durante o armazenamento

Foi realizado um trabalho com o objetivo de isolar e identificar os microrganismos presentes em sementes de cafe robusta (Coffea canephora Pierre ex Froehner) no decorrer do armazenamento. Para tanto, sementes de cafe do cultivar Conillon, acondicionadas em diferentes embalagens (saco de polietileno transparente, saco de papel kraft e saco de algodao) e com graus de umidade iniciais distintos (25 e 35%) foram submetidas a cinco periodos de armazenamento (0, 3, 6, 9 e 12 meses), em condicoes controladas. Apos cada um desses periodos, as sementes foram avaliadas, em laboratorio, quanto a sanidade (metodo do papel-filtro), germinacao e grau de umidade. Foram isolados e identificados cinco generos dife-rentes de fungos infestando as sementes de cafe robusta, a saber: Fusarium semitectum, Colletotrichum spp., Alternaria spp., Aspergillus spp. e Penicillium spp. Observou-se predominância de Fusarium semitectum e de Alternaria spp., no inicio do armazenamento das sementes, com incidencia variando de 63-73% e 7-11% respectivamente. No decorrer do armazenamento, houve grande elevacao na incidencia dos fungos de armazenamento dos generos Aspergillus spp. e Penicillium spp. nas sementes acondicionadas em diferentes embalagens. A incidencia dos microrganismos mostrou grande variacao, em funcao do tipo de embalagem utilizado durante o armazenamento. O aumento na incidencia dos microrganismos esteve associado com a reducao na germinacao das sementes de cafe. O fungo Fusarium semitectum manteve-se em niveis elevados ate por 12 meses nas sementes acondicionadas em embalagens de papel kraft e algodao. A embalagem de polietileno, associada ao grau de umidade inicial mais elevado, foi mais favoravel na conservacao das sementes de cafe robusta.