Germination of Urochloa ruziziensis seeds according to substrate water availability and seeds moisture content

Water stress and seed water content can affect the first germination stages and disturb the full pasture establishment. This study aimed at evaluating the effect of substrate water availability and seed water content on the germination of Urochloa ruziziensis seeds, as well as verifying any harmful effect of seed imbibition. The treatments consisted of seeds with 9.5%, 11.3% and 14.6% of moisture content, subjected to substrate water availability simulated with aqueous solutions of polyethylene glycol 6000 (PEG 6000) of 0.0 MPa (PubMed control), -0.1 MPa, -0.2 MPa, -0.3 MPa and -0.4 MPa. The following characteristics were used to evaluate the seeds physiological quality: germination percentage and first counting, aerial and primary root length and seedlings fresh weight. The experimental design was completely randomized, with four replications of 50 seeds. All the evaluated characteristics were negatively influenced by the water potentials reduction, however, the U. ruziziensis seeds with 11.3% and 14.6% of moisture content showed a higher germination rate and seedlings growth at low water availability. Despite the reduction in the indexes evaluated for water deficiency, the damage extension in seeds was determined by seeds moisture content and water stress severity

Substrate water availability and seed water content on niger germination

Niger is an oleaginous species whose cultivation has been spreading, but there is not much information on the adverse conditions during its seedling establishment. This study aimed at evaluating the effects of substrate water availability and seed water content on niger germination. Seeds were moistened using the humid atmosphere method for 0; 24; 48; and 72 hours, obtaining the water contents of 7.0 %, 12.8 %, 16.8 % and 32.2 %. Then, they were sown in substrate moistened with PEG 6000 solutions with different osmotic potentials: 0.0 MPa (control), -0.1 MPa, -0.2 MPa, -0.3 MPa and -0.4 MPa. A completely randomized design, in a 4 x 5 factorial scheme (water content x osmotic potential), with four replications of 50 seeds, was used. First count and germination percentage, germination speed index and mean time, shoot and root length and seedlings dry weight were evaluated. The reduction in the substrate osmotic potential decreases the niger seed germination and seedling growth, regardless of water content, but with a higher evidence in seed water contents below 32.2 % and 12.8 %, respectively

Germination and vigor of Campomanesia adamantium seeds according to fruit and seed size

The knowledge on biometric aspects of fruits and seeds and their influence on germination are important for the production and properties of native species. This study aimed at evaluating the influence of fruit and seed size on the germination and vigor of Campomanesia adamantium seeds. For the biometric characterization, 120 fruits were randomly selected and visually divided into four classes, with predominance for size, in which longitudinal and transversal diameters and mass of seeds were measured. The seed characterization was carried out in 30 fruits of each class, by determining the number of whole, empty and total seeds of every fruit. The seeds physiological potential, according to fruit size, was evaluated with the aid of the following tests: imbibition curve, moisture content, germination percentage and speed index, seedling length, total fresh and dry matter of seedlings. A completely randomized design, with four treatments, was used. Fruits were respectively classified according to their longitudinal and transversal diameters as small (12.71 mm; 12.46 mm), medium small (15.38 mm; 15.01 mm), medium large (18.84 mm; 18.02 mm) and large (22.74 mm; 22.36 mm). The classes of small, medium small and medium large fruits presented seeds with higher germination percentage and speed index, while seedlings with higher biomass accumulation were observed for large fruits

Germinação de sementes de Dimorphandra mollis Benth.: efeito de salinidade e condicionamento osmótico

This work aimed to study the effects of salt stress and the osmotic conditioning on the physiological quality of D. mollis seeds. It was carried out two experiments with previously acetone imbibed seeds for dormancy release. The first one evaluated the effect of CaCl2 and NaCl saline solutions osmotic potentials at: 0.0 (control), -0.4, -0.8, -1.5 and -2.0 MPa on seeds percentage germination and germination speed index of 2006 seeds lot.  In the second experiment, the faveiro seeds were imbibed in polyethyleneglicol solutions (PEG 6000) at 0,0 (control), -0.3, -0.7, -1.0 and -1.3 MPa potentials. The different concentration levels of CaCl2 and NaCl affected negatively the seeds physiological quality, reduced significantly the germination and IVG. The seeds osmotic conditioning at -0.3 and -0.7 MPa provided a significant increment in the seeds germination percentage and germination speed index. The osmotic conditioning presented favorable immediate effects, accelerating the D. mollis seeds germination.Objetivou-se com este trabalho avaliar o efeito do estresse salino com soluções de CaCl2 e NaCl nos potenciais osmóticos de 0,0 (controle), -0,4, -0,8, -1,5 e -2,0 MPa e o efeito do condicionamento osmótico com soluções de polietilenoglicol (PEG 6000) nos potenciais de 0,0 (controle), -0,3, -0,7, -1,0 e -1,3 MPa durante cinco dias na germinação de sementes de faveiro. Os diferentes níveis de concentração de CaCl2 e NaCl afetaram negativamente a qualidade fisiológica das sementes de faveiro, reduzindo significativamente a germinação e o IVG. O condicionamento das sementes a -0,3 e -0,7 MPa proporcionaram um incremento significativo na porcentagem e índice de velocidade de germinação das sementes. As sementes de D. mollis apresentam sensibilidade à salinidade causada pela redução do potencial hídrico com NaCl e CaCl2 a partir de -0,4 MPa. O condicionamento osmótico apresenta efeitos imediatos favoráveis, acelerando a germinação das sementes de faveiro

Quality of second season soybean submitted to drying and storage

Drying agricultural products reduces the moisture content to suitable levels for storage, in order to maintain the product quality. However, special care with the temperatures applied in the process is important for the integrity and longevity of the material. The present study aimed at determining the immediate and latent effect of air-drying temperatures on the quality of soybean produced as a second season crop. The grains were collected at the R8 stage, close to the physiological maturity, with moisture content of approximately 23 % (w.b.), submitted to drying temperatures of 40 ºC, 50 ºC, 60 ºC, 70 ºC and 80 ºC, up to a moisture content of 12.5 ± 0.7 % (w.b.), and then stored under non-controlled humidity and temperature for 180 days. Thereafter, quality was assessed every 45 days by determining the dry matter loss, color and crude protein and lipid contents, as well as the acidity and peroxide indices of the crude oil extracted. Based on the results obtained, it was concluded that the increase in the air-drying temperature affects the soybean quality and crude oil extracted, being this effect enhanced with the storage time; the soybean and crude oil quality decline with an increase in the air-drying temperature and storage time; the air temperature of 40 ºC has the least effect on the quality of soybean grains and crude oil extracted

Qualidade fisiológica de sementes de soja produzidas em duas épocas de semeadura no sudoeste do Paraná

A região sudoeste do Paraná é tradicionalmente conhecida por apresentar características favoráveis à produção de sementes de soja com qualidade elevada. O objetivo do presente trabalho foi avaliar o potencial fisiológico das sementes de nove genótipos de soja produzidos em duas épocas de semeadura, por meio dos testes de germinação e vigor, identificando a época de plantio que proporcione sementes de soja com alta qualidade fisiológica. O experimento foi implantado no município de Mariópolis, sudoeste do Paraná, utilizando-se a semeadura antecipada em 15 de setembro de 2011e tardia em 10 de janeiro de 2012 de nove genótipos de soja. O potencial fisiológico das sementes foi avaliado por meio do teste de germinação, teste de emergência, comprimento, massas fresca e seca da parte aérea e da raiz das plântulas. Os genótipos e as épocas de semeadura influenciaram significativamente os caracteres qualitativos do potencial fisiológico das sementes de soja, sendo que as sementes produzidas na primeira época não atingiram o padrão mínimo para comercialização de sementes de soja. A semeadura na segunda época proporciona sementes com maior germinação e vigor em relação às sementes produzidas na primeira época de semeadura