Rodrigo Ramos Lopes

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.

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.

Aspectos térmico-biológicos da germinação de sementes de cornichão anual sob diferentes temperaturas

The objective of this research was to determine the minimal, optimal and maximal temperatures for seed germination of Lotus subbiflorus Lag., using germination percentage, speed, frequency, informational entropy and enthalpy of activation of germination. The experiment was carried out in two lots with four replicates of 100 seeds each. The data were submitted to variance analysis and means were compared by Tukeys test. Eight constant temperatures (0, 5, 10, 15, 20, 25, 30 and 35 oC) and light exposition (darkness and 8 h of light plus 16 h of darkness) were used. This species of seed germinates in a temperature range of minimal values between 0 and 5 oC, optimal values between 15 and 20 oC and maximal values between 30 and 35 oC. Germination rate was temperature dependent. The highest values of speed germination, occurring between 15 and 20 oC below and above this range germination speed had a significant reduction. The lowest values of informational entropy occurred between 15 and 20 oC, showing a higher synchronization of germination process in these temperatures. The enthalpy value of the system was calculated, reaching its minimum point at 278 K, and its maximum, at 303 K; the point at which the curve crossed the absciss axis was 290.5 K

Temperature requirements for seed germination of Pereskia aculeata and Pereskia grandifolia.

Pereskia aculeata and Pereskia grandifolia have been studied widely due to their high nutritional and therapeutic values. However, little is known about the biological requirements of their seeds for the various germination factors. Thus, this experiment aimed to evaluate the thermal effects on the germination of these species at the temperatures of 24°C, 27°C, 30°C, 33°C and 36°C. After verification of the existence of differences in the performance of germination, a non-linear regression was carried out, relating the germination to temperature and identifying its point of maximum efficiency. We found that the lowest synchronization indexes of germination were observed close to 30°C. The best germination response of the P. aculeata and P. grandifolia was observed at 30°C and 33°C, respectively, with greater germination strength and fewer days to attain 63.21% of germinations. The results obtained from the germination of P. aculeata and P. grandifolia can be described by the Weindull distribution model with three parameters, as proposed by Carneiro and Guedes (1992).

Overcoming dormancy and determining optimal temperature for slender serradella seed germination

The objective of this study was to identify the most efficient method for overcoming coat-imposed dormancy and determine the optimal germination temperature for Ornithopus pinnatus seeds. Treatments to overcome dormancy were: intact seeds; immersion in hot water at 60 oC, followed by soaking in the same water (unheated)/24 h; immersion in hot water at 90 oC, followed by soaking in the same water (unheated)/24 h; mechanical scarification; chemical scarification, H2SO4/5 min; and chemical scarification, H2SO4/10 min. Percentages were calculated for germinated, abnormal, dormant, and dead seeds. Optimal germination temperatures were calculated using eight constant temperatures (0, 5, 10, 15, 20, 25, 30, and 35 °C), with 8 h of light and 16 h of darkness. Germination rate, frequency, and synchronization index of germination were used as parameters to establish optimum temperature for germination. A completely randomized experimental design was used, with twelve repetitions of 100 seeds per treatment. Data obtained were subjected to analysis of variance and Tukeys test at a 5% significance level. O. pinnatus seeds exhibit dormancy caused by the seed coats impermeability to water. Mechanical scarification was efficient in promoting seed germination. The species is stenothermal, meaning it cannot tolerate significant temperature variations. The germination rate of seeds was linearly dependent on temperature. Synchronization of the germination process is greater in the optimum temperature range, established between 15 and 20 °C.

Avaliação do potencial de produção de sementes de acessos de trevo branco

This work was carried out to evaluate the potential of seed production of 25 accessions of the basic collection of white clover from the United States Department of Agriculture. Through weekly samplings performed from 11/6th/2003 to 3/10th/04 the following variables were analyzed: number of inflorescence/plant, number of flowers/inflorescence, number of mature inflorescence/plant, number of mature legumes/inflorescence, weight of 1000 seeds, and seed yield/plant. It was used a complete randomized experimental design with the accessions individually arranged in five replications. Seed yield of white clover is highly affected by number of inflorescence/plant, number of mature inflorescence/plant, and weight of 1000 seeds. The 53, 2 and 20 accessions differ from the others because of their superiority (7, 68, 19, 79, 58, 3, 15, 75, 64, 50, 33, 13, 59, 38, 28, 80, 54, 29, 31, 23, 22, 27, 65 and 73) of seed production. The accessions 27, 65 and 73 do not produce seeds in the local conditions during the first year of evaluation.