Physiological potential of rice seeds treated with rhizobacteria or the insecticide thiamethoxam

Development of new technologies, aiming at increasing productivity in different crops, involves constant research on the effectiveness and application of these techniques in seed treatment. In this study, it was aimed at evaluating physiological potential of rice seeds treated with plant growth-promoting rhizobacteria (PGPR) (strains DFs185, DFs223, DFs306, DFs416), or with two dosages of the insecticide thiamethoxam. The variables assessed were: germination (G); first count of germination (FCG); cold test (CT); length of seedlings aerial parts (LAP), root system (LRS), and total length (TL); emergence speed index (ESI); emergence (E), at 14 days; and dry phytomass (DP). Treatments have had a positive effect on percentage of G, FCG and E. The strain DFs185 has promoted increase in percentage emergence, for five of the six lots assessed. The variables: LAP; LRS; TL; ESI; and DP have undergone low or none influence of treatments; and there has been no toxic effect of rhizobacteria or insecticide thiamethoxam. In the cold test, a negative effect of treatments has been detected. Seed treatment with rhizobacteria, as well as with thiamethoxam, improve quality of low quality rice seeds. The strain DFs185 is promising for treating rice seeds, once it stimulates seed germination and emergence.

Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions

Prediction of the solar wind conditions in near-Earth space, arising from both quasi-steady and transient structures, is essential for space weather forecasting. To achieve forecast lead times of a day or more, such predictions must be made on the basis of remote solar observations. A number of empirical prediction schemes have been proposed to forecast the transit time and speed of coronal mass ejections (CMEs) at 1 AU. However, the current lack of magnetic field measurements in the corona severely limits our ability to forecast the 1 AU magnetic field strengths resulting from interplanetary CMEs (ICMEs). In this study we investigate the relation between the characteristic magnetic field strengths and speeds of both magnetic cloud and noncloud ICMEs at 1 AU. Correlation between field and speed is found to be significant only in the sheath region ahead of magnetic clouds, not within the clouds themselves. The lack of such a relation in the sheaths ahead of noncloud ICMEs is consistent with such ICMEs being skimming encounters of magnetic clouds, though other explanations are also put forward. Linear fits to the radial speed profiles of ejecta reveal that faster-traveling ICMEs are also expanding more at 1 AU. We combine these empirical relations to form a prediction scheme for the magnetic field strength in the sheaths ahead of magnetic clouds and also suggest a method for predicting the radial speed profile through an ICME on the basis of upstream measurements.

Seed dormancy and germination of Ficus lundellii and tropical forest restoration

We investigated seed dormancy and germination in Ficus lundellii Standl. (Moraceae), a native species of Mexico's Los Tuxtlas tropical rain forest. In an 8-h photoperiod at an alternating diurnal (16/8 h) temperature of 20/30 degrees C, germination was essentially complete (96%) within 28 days, whereas in darkness, all seeds remained dormant. Neither potassium nitrate (0.05-0.2%) applied continuously nor gibberellic acid applied either continuously (10-200 ppm) or as a 24 hour pretreatment (2000 ppm) induced germination in the dark. Germination in the light was not reduced by a 24-h hydrochloric acid (0.1-1%) pretreatment, but it was reduced both by a 24-h pretreatment with either H2O2 (0. 1-5 M) or 5% HCl, or by more than 5 days of storage at 40 degrees C (4.5% seed water content). In a study with a 2-dimensional temperature gradient plate, seeds germinated fully and rapidly in the light at a constant temperature of 30 degrees C, and fully but less rapidly in the light at alternating temperatures with low amplitudes (< 12 degrees C) about the optimal constant temperature. The base, optimal and ceiling temperatures for rate of germination were estimated as 13.8, 30.1 and 41.1 degrees C, respectively. In all temperature regimes, light was essential for the germination of F lundellii seeds.

Assessing the accuracy of CME speed and trajectory estimates from STEREO observations through a comparison of independent methods

We have estimated the speed and direction of propagation of a number of Coronal Mass Ejections (CMEs) using single-spacecraft data from the STEREO Heliospheric Imager (HI) wide-field cameras. In general, these values are in good agreement with those predicted by Thernisien, Vourlidas, and Howard in Solar Phys. 256, 111 -aEuro parts per thousand 130 (2009) using a forward modelling method to fit CMEs imaged by the STEREO COR2 coronagraphs. The directions of the CMEs predicted by both techniques are in good agreement despite the fact that many of the CMEs under study travel in directions that cause them to fade rapidly in the HI images. The velocities estimated from both techniques are in general agreement although there are some interesting differences that may provide evidence for the influence of the ambient solar wind on the speed of CMEs. The majority of CMEs with a velocity estimated to be below 400 km s(-1) in the COR2 field of view have higher estimated velocities in the HI field of view, while, conversely, those with COR2 velocities estimated to be above 400 km s(-1) have lower estimated HI velocities. We interpret this as evidence for the deceleration of fast CMEs and the acceleration of slower CMEs by interaction with the ambient solar wind beyond the COR2 field of view. We also show that the uncertainties in our derived parameters are influenced by the range of elongations over which each CME can be tracked. In order to reduce the uncertainty in the predicted arrival time of a CME at 1 Astronomical Unit (AU) to within six hours, the CME needs to be tracked out to at least 30 degrees elongation. This is in good agreement with predictions of the accuracy of our technique based on Monte Carlo simulations.

Age related changes in speed and mechanism of adult skeletal muscle stem cell migration

Skeletal muscle undergoes a progressive age-related loss in mass and function. Preservation of muscle mass depends in part on satellite cells, the resident stem cells of skeletal muscle. Reduced satellite cell function may contribute to the age-associated decrease in muscle mass. Here we focused on characterising the effect of age on satellite cell migration. We report that aged satellite cells migrate at less than half the speed of young cells. In addition, aged cells show abnormal membrane extension and retraction characteristics required for amoeboid based cell migration. Aged satellite cells displayed low levels of integrin expression. By deploying a mathematical model approach to investigate mechanism of migration, we have found that young satellite cells move in a random ‘memoryless’ manner whereas old cells demonstrate superdiffusive tendencies. Most importantly, we show that nitric oxide, a key regulator of cell migration, reversed the loss in migration speed and reinstated the unbiased mechanism of movement in aged satellite cells. Finally we found that although Hepatocyte Growth Factor increased the rate of aged satellite cell movement it did not restore the memoryless migration characteristics displayed in young cells. Our study shows that satellite cell migration, a key component of skeletal muscle regeneration, is compromised during aging. However, we propose clinically approved drugs could be used to overcome these detrimental changes.

Default perception of high-speed motion

When human observers are exposed to even slight motion signals followed by brief visual transients—stimuli containing no detectable coherent motion signals—they perceive large and salient illusory jumps. This novel effect, which we call “high phi”, challenges well-entrenched assumptions about the perception of motion, namely the minimal-motion principle and the breakdown of coherent motion perception with steps above an upper limit. Our experiments with transients such as texture randomization or contrast reversal show that the magnitude of the jump depends on spatial frequency and transient duration, but not on the speed of the inducing motion signals, and the direction of the jump depends on the duration of the inducer. Jump magnitude is robust across jump directions and different types of transient. In addition, when a texture is actually displaced by a large step beyond dmax, a breakdown of coherent motion perception is expected, but in the presence of an inducer observers again perceive coherent displacements at or just above dmax. In sum, across a large variety of stimuli, we find that when incoherent motion noise is preceded by a small bias, instead of perceiving little or no motion, as suggested by the minimal-motion principle, observers perceive jumps whose amplitude closely follows their own dmax limits.

Electrical conductivity test in the evaluation of physiological quality in seeds of Zeyheria tuberculosa

The electrical conductivity test is still an excellent tool to evaluate the effect of seeds of various forest and agricultural species and recent studies have been conducted aiming at verifying its application in forest seeds. The objective of this study was to establish a specific methodology to test the electrical conductivity of forest seeds of Zeyheria tuberculosis. Four lots of seeds were used, which were submitted to the germination test, evaluating the percentage of germination, germination speed index and dry mass of seedlings. For the electrical conductivity test, five replicates of 20 seeds installed in three volumes of deionized water (75, 100 and 125 mL) were used and eight periods for seed imbibitions (2, 4, 6, 12, 18, 24, 48 and 72 hour) at 25 degrees C were allowed. The statistical design used was completely random; the comparison of means was performed by Tukey test at 5 % probability. Lot II showed higher germination percentage and speed. The electrical conductivity test allows discrimination of the same batch by the germination test under laboratory conditions. It was possible to separate the seed lot presenting better physiological quality (lot II) from among the other lots. It was recommended the use of 75 or 125 mL of deionized water at a temperature of 25 degrees C to perform the electrical conductivity test.

Influence of the temperature in germination of seeds of jabuticaba tree

A jabuticabeira (Myrciaria spp.) é uma fruteira originada do centro-Sul do Brasil e apresenta tipos diferentes. É uma árvore de tamanho médio, com tendência a formar copa com grande número de ramos desde pouco acima do solo. Uma característica considerada como limitante para a cultura comercial dessa frutífera é o grande período juvenil, aconselhando-se então produzir bons porta-enxertos de pés-francos e enxertar as variedades desejadas, ou ainda por outros processos vegetativos. Objetivando-se avaliar a influência da temperatura na germinação de sementes de três clones de jabuticabeira, realizou-se um experimento em condições de laboratório. Observou-se que há influência da temperatura na porcentagem de germinação, sendo que, nas mais baixas temperaturas (15ºC e 20ºC), foi verificada uma maior porcentagem de germinação para os três clones em estudo. Quando do uso da temperatura de 35ºC, dois clones tiveram apenas 8% de germinação, enquanto, para o outro, foi verificado 35%. Estes dados mostram a possibilidade de ocorrência de variabilidade entre clones de jabuticabeira.

Mechanism and control of Genipa americana seed germination

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Isolation and mycelial growth of Diehliomyces microsporus: effect of culture medium and incubation temperature

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phosphorus rates on yield and quality of lettuce seeds

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Effect of chickpea (Cicer arietinum L.) germination on the major globulin content and in vitro digestibility

A germinação das sementes de grão-de-bico foi acompanhada por um período de 6 dias, no qual pequenas variações nos teores de nitrogênio e globulina total foram registradas. A globulina majoritária (tipo 11 S) apresentou maiores variações após o quarto dia de germinação. A natureza e distribuição da fração globulina majoritária isolada na cromatografia em Sepharose CL-6B mostrou pequenas modificações ao final do período de germinação. A eletroforese em gel de poliacrilamida com dodecilssulfato de sódio do pico eluído na cromatografia em Sepharose CL-6B demonstra modificações nas bandas de proteínas entre os pesos moleculares de 20 e 30 kDa e acima de 60 kDa, indicando degradação protéica durante o período. Atividade proteolítica foi detectada na fração albumina da semente que aumentou até o quarto dia, seguido de queda até o sexto dia de germinação, quando da utilização de globulina total isolada da semente e caseína como substratos. Farinha de grão-de-bico, frações albumina e globulina total isoladas não apresentaram aumento na digestibilidade in vitro; entretanto, a fração globulina majoritária isolada foi mais suscetível à hidrólise após germinação.

Performance of aerodynamic baffles in cylindrical grinding analyzed on the basis of air layer pressure and speed

Over the years, grinding has been considered one of the most important manufacturing processes. Grinding is a high precision process, and the loss of a single workpiece in this stage of the production is unacceptable, fir the value added to the material is very high due to many processes it has already undergone prior to grinding. This study aims to contribute toward the development of an experimental methodology whereby the pressure and speed of the air layer produced by the high rotation of the grinding wheel is evaluated with and without baffles, i.e., in an optimized grinding operation and in a traditional one. Tests were also carried out with steel samples to check the difference in grinding wheel wear with and without the use of baffles.

Scarification, temperature and light in germination of Senna occidentalis seed (Caesalpinaceae)

The purpose of the present work was to study various aspects of the germination of seeds of Senna occidentalis Link, which had presented promising results in biological activity against the etiological agent of malaria. These aspects were dormancy, temperatures of germination and photoblastic response. In the dormancy studies, the treatments used were: unscarified seed (control); tegument puncture with sharp point; and scarification with sand-paper and immersion in concentrated sulfuric acid during 5, 10, 15 and 20 minutes. For the study of temperature and photoblast, the seeds were immersed in sulfuric acid for 20 minutes, submitted to temperatures of 10 to 45degreesC, at intervals of 5degreesC, both under light and in the dark. The seeds presented dormancy related to tegument, the best treatments for breaking dormancy were immersion in sulfuric acid for 15 and 20 minutes. At temperatures 25 and 30degreesC, the best results of percentage and index of velocity of germination were observed, at which the seeds behaved as neutral photoblastic; there was no germination at 10 or at 45degreesC.

Effects of different environmental stresses on seed germination

In this paper, the hypothesis was that different environmental stresses may show similar responses in a biological system, as exemplified by the kinetic of germination of Eucalyptus grandis W. Hill ex Maiden seeds. It was observed that the kinetic of germination depends on environmental factors, and different treatments induced similar germination responses. The treatments with PEG 6000 and NaCl suggest that germination depends on solute used, since NaCl exhibit both ionic and osmotic effects. The analysis of the results showed that different external disturbances may lead, perhaps through different physiological ways, to similar responses related to the germination process.