Lucia Brandão Franke

Efeitos do condicionamento osmótico na qualidade fisiológica de sementes de Adesmia latifolia (Spreng.) Vog.

Desiccation tolerance acquisition is a phenomenon which may occur during the development of seeds of several species, but it has been little investigated for coffee seeds. The present research was carried out to ascertain at which stage of coffee seed development tolerance to desiccation is acquired. Seeds of Coffea arabica cultivar Acaia Cerrado harvested at three maturation stages, green, yellow and reddish were used. Part of the seeds was dried in forced air, under constant temperature of 30oC until the seed moisture content reached 15%. Then the seeds were stored in hermetic containers in a cool chamber at 10oC and 50% relative humidity. The evaluation was made after zero, 3, 6 and 9 months of storage, looking at moisture content, physiological conditions through the germination test, radical protrusion, percentage of secondary roots, emergence in growth room, emergence speed index. According to the results it was possible to conclude that coffee seeds present an increased desiccation tolerance as they reach later development stages. Seeds harvested at the green and yellow stages presented a decline in the production of secondary roots and percentage of seedling emergence. Drying seeds to 15% moisture content provided conditions to keep physiological quality throughout 9 months storage at 10oC and 50% relative humidity. Non dried seeds (50% moisture content) presented a linear reduction in the physiological quality when stored at 10oC, 50% relative humidity in hermetic containers.RESUMO - Considerando que a especie Adesmia latifolia (Spreng.) Vog. apresenta estabelecimento lento, aliado a dureza do tegumento de suas sementes, o que contribui para uma emergencia desuniforme, este trabalho teve como objetivo investigar os efeitos do condicionamento osmotico na qualidade fisiologica, avaliando-se a percentagem final e velocidade de germinacao, comprimento medio das plântulas e indices de materia fresca e materia seca das plântulas, em laboratorio e em canteiros. Para o condicionamento osmotico as sementes foram embebidas por dois dias em solucao de polietilenoglicol (200g/l)), aquecida a uma temperatura inicial de 70°C e posteriormente resfriada a 20°C. Alem da testemunha nao osmocondicionada, as sementes tambem foram colocadas em agua quente a 60°C e semeadas em canteiros, em linhas, num delineamento em blocos completamente casualizados, com quatro repeticoes de 40 sementes cada. As sementes osmocondicionadas de A. latifolia mostraram desempenho fisiologico superior (P<0,05) na percentagem final e na velocidade de germinacao, no comprimento medio das plântulas e nos indices de materia fresca e materia seca das plântulas tanto em canteiros, como em laboratorio. O condicionamento osmotico com aquecimento da solucao, alem de melhorar o desempenho das sementes de A. latifolia foi eficiente em superar a dormencia, nao sendo necessaria a utilizacao de metodos normalmente aplicados em leguminosas.

SUPERAÇÃO DE DORMÊNCIA E METODOLOGIAS PARA TESTES DE GERMINAÇÃO EM SEMENTES DE Trifolium riograndense Burkart E Desmanthus depressus Humb.

RESUMO – O objetivo deste trabalho foi estudar metodos para superacao da dormencia e conducao do teste de germinacao em sementes de Trifolium riograndense Burkart e Desmanthus depressus Humb., leguminosas nativas ainda nao relacionadas nas Regras para Analise de Sementes vigentes. O experimento foi dividido em duas etapas: na primeira, objetivando a superacao da dormencia, foram testados os tratamentos imersao em agua aquecida a 60°C, por cinco minutos; escarificacao quimica com acido sulfurico concentrado por cinco minutos e escarificacao manual com lixa n°180. Para a determinacao das condicoes para o teste de germinacao, avaliou-se os parâmetros luz (presenca e ausencia), substratos (papel e areia), posicao da semente no substrato (sobre e entre) e diferentes temperaturas constantes (5, 10, 15, 20, 25 e 30°C). O delineamento experimental utilizado foi o completamente casualizado, com quatro repeticoes de 25 sementes cada. A imersao em agua aquecida e a escarificacao manual do tegumento com lixa sao os tratamentos mais eficientes para a superacao da dormencia em sementes de D. depressus e T. riograndense, respectivamente. As sementes de D. depressus apresentam maior germinacao na presenca de luz, sobre substrato papel, a 25°C, e as sementes de T. riograndense na ausencia de luz, sobre substrato papel, a 30°C. A temperatura alternada de 20-30°C e considerada adequada para a conducao do teste de germinacao, para ambas as especies.

PERfORMANcE Of DIffERENT DRYING METHODS AND THEIR EffEcTS ON THE PHYSIOLOGIcAL quALITY Of GRAIN SORGHuM SEEDS (S. bicolor (L.) Moench) 1

This experiment viewed to evaluate the physiological quality of grain sorghum seeds as well as to determine the respective drying curve of each of three drying methods. The seeds harvested at 18.9%, 18.1%, and 18.2% of moisture content were submitted to the following drying methods : a) under natural conditions, b) an intermittent dryer in which the combustion of firewood was the source of caloric energy, and c) a stationary dryer in which the source of caloric energy was the burning of liquefied petroleum gas. The experimental design was a completely randomized one with 25 repetitions of one hundred seeds each. The water contents and weight of one thousand seeds were evaluated. Seeds physiological quality was evaluated by germination and vigor tests. Seed drying rates were of 0.11, 1.25, and 0.55 percent points per hour (pph -1 ) for the natural, intermittent and stationary drying methods, respectively. The intermittent treatment permits the highest loss of water in the shortest period of time, and germination and vigor remaining unchanged.

Produção de sementes de quatro ecótipos de Paspalum nativos do Rio Grande do Sul

The objective of this study was to investigate components of production and seed production of two Paspalum species. It was evaluated two ecotypes of Paspalum notatum and Bagual) and two ecotypes of Paspalm urvillei (Andre da Rocha and Eldorado do Sul). It was used a complete randomized experimental design, in a factorial scheme (ecotypes x days after planting), with five replicates nested within days after planting. Each species was analyzed separately for determination of the components of production and seed production. The variables were measured weekly from November 7th 2006 to March 31st 2007. The following variables were evaluated: number of vegetative tillers, number of reproductive tillers/m2, percentage of fertile tillers, number of racemes/m2, weight of 1000 seeds, number of seeds/inflorescence, number of seeds/raceme and seed yield per area. Seed production of Paspalum is negatively affected by the long flowering period and by the capacity of retention by the seeds in the inflorescence. Seed production differs among ecotypes inasmuch as mean values were 47.17 kg/ha (Paspalum notatum Andre da Rocha), 61.01 kg/ha (Paspalum notatum Bagual), 30.60 kg/ha (Paspalm urvillei Andre da Rocha) and 47.95 kg/ha (Paspalm urvillei Eldorado do Sul). Seed production of those species is highly affected by the number of reproductive tillers, by the percentage of fertile tillers and by the weight of 1000 seeds.

Teste de condutividade elétrica para avaliação da qualidade fisiológica de sementes de azevém (Lolium multiflorum L.)

The electrical conductivity test has the potential to be used by seed companies in quality control but some factors can affect the results of the EC. The object of this study was to evaluate the effect of the number of seeds, water volume and the imbibition time on the electrical conductivity of the solution, on ryegrass seed vigour. Four lots of common ryegrass seeds were used. The test was made at 25 oC, at imbibition testing times of 1, 2, 4, 6, 8, and 24 hours, in 50 and 75mL water, using 50 and 100 seeds. The treatments constituted a factorial, using a completely randomized design with four repetitions. The use of four subsamples of 50 pure seeds soaked in 50mL of de-ionized water is promising for the use of the electrical conductivity test of ryegrass seeds conducted after 1 hour of soaking.

Análise de trilha dos componentes do rendimento de sementes de trevo-branco

The objective of this study was, by using a path analysis of seed yield in white clover, to obtain basic information for use in management strategies for higher seed production and higher natural reseeding and greater persistence of the species in the pasture. The following variables were analyzed: number of flower buds, number of inflorescences, number of mature inflorescences, number of legumes/inflorescence, weight of 100 seeds and seed yield. The variable most correlated with seed yield was the number of mature inflorescences (r = 0.91), and this correlation occurred almost only due to its direct effect. Among the other variables, the number of flower buds also had a high correlation coefficient (r = 0.55) and indirect effects on the other components. The number of mature inflorescences appeared to be the main characteristic to be considered when searching for a higher seed production in white clover.

Substrato e luz na germinação das sementes de rainha-do-abismo

Sinningia lineata is a rock growing plant, with ornamental potential, which is in danger of extinction. This study aimed at analyzing the germinative behavior of the S. Ilineata in different substratums and light conditions. The results should contribute to the sexual propagation aiming at the conservation ex situ, as well as to offer a subsidy for its inclusion as an ornamental plant. The seeds were collected in situ. Six substrata were tested in presence and absence of light incidence: blotting paper, medium river sand, commercial substratum, mixture in the proportion of 1:1 of sand with carbonated rice husk, sand with commercial substratum, and carbonated rice husk with commercial substratum. The temperature was of 20oC. The technical concept of germination was adopted, development of normal plantlets. The results indicated that the lot had a high germination capability, which was demonstrated by the high germination percentage on the paper (92,5%). The germination and vigor tests indicated that among the studied substrata, the blotting paper and sand were the best. The germination percentage in sand was 90% and did not differ statistically from the percentage of germination on paper. The other substrata were not considered adequate for seed germination of the species. The chemical analyses of the commercial substratum presented high salinity levels, which caused a gradual loss of seedlings, indicating that the species is sensitive to this chemical condition. The test with light demonstrated that the species is a positive photoblastic.

Correlação e análise do coeficiente de trilha dos componentes do rendimento de sementes de grama-forquilha

Objetivou-se com este trabalho, por meio de uma analise de trilha para rendimento de sementes de grama-forquilha (Paspalum notatum Flugge var. notatum), obter informacoes basicas para utilizacao em estrategias de manejo para maior producao de sementes e, consequentemente, maior ressemeadura natural, proporcionando, assim, condicoes para maior persistencia da especie na pastagem. Foram analisadas as seguintes variaveis: numero de perfilhos vegetativos, numero de perfilhos reprodutivos, numero de racemos/inflorescencia, numero de sementes/inflorescencia, peso de mil sementes e rendimento de sementes. A variavel que mais se correlacionou com o rendimento de sementes foi o numero de perfilhos reprodutivos (r = 0,94), e essa correlacao se deu praticamente apenas pelo efeito direto dessa variavel. Entre as demais variaveis, destacou-se o numero de perfilhos vegetativos, com coeficiente de correlacao de -0,83 e efeitos indiretos sobre os demais componentes do rendimento de sementes. O numero de perfilhos reprodutivos parece ser a principal caracteristica a ser considerada na busca de maior producao de sementes de Paspalum notatum.

Efeito da polinização sobre a produção e qualidade de sementes de Adesmia latifolia

With the objective of studying the effect of the pollination efficiency of Apis mellifera L. and the performance on seed yield and quality of Adesmia latifolia (Spreng.) Vog., an experiment was setup at the Agronomic Experimental Station of the UFRGS in Eldorado do Sul in 2000, 2001 and 2002. Three treatments were established at the beginning of the flowering season: the presence only of honeybees, A. mellifera (a); exclusion of honeybees and all other insects (b) using in both treatments two nylon net cages, and free access to honeybees and all other insects (c). Mean seed production on the three years was 5.4 and 85.5 kg/ha on the treatments a and c, respectively. In the isolated area (b) there were no legumes and seed formation and the number of flowers unfertilized was high, which made these plants dependent on pollinator insects. It was concluded that A. mellifera was not efficient in A. latifolia pollination. A. mellifera collects nectar between the calyx and the corolla and therefore does not expose the flower reproductive organs. A. latifolia depends on wild bees such as Megachille sp. and Centris sp. for adequate pollination.

QUALIDADE DE SEMENTES DE ACESSOS DE MELÃO CRIOULO (Cucumis melo L.) 1

This study aimed to evaluate the quality of seeds from six landrace melon (Cucumis melo L.) accessions, obtained from family farms across different zones in the state of Rio Grande do Sul. The assays were carried out in the Seed Analysis Laboratory, Ministry of Agriculture (LASO/ LANAGRO-RS), and in the Seed Laboratory Department of Forage Plants and Agrometeorology, Faculty of Agronomy, Federal University of Rio Grande do Sul (UFRGS). Samples were evaluated by the weight of one thousand seeds, germination test, first count, germination speed index, seedling dry weight, seedling size and accelerated aging test. The seeds of traditional melon accessions showed significant variation in color and size. All the accessions had more than 80% germination, regardless of post-harvest and storage management, indicating that the use of these varieties can be increased. The accelerated aging test did not permit ranking of the seed vigor level. Sanitary tests did not reveal viruses or bacteria in the seeds investigated, although Phoma sp., Cladosporium sp. and Fusarium sp. were detected in some accessions.