Oscar José Smiderle

Tratamentos pré-germinativos em sementes de acácia

The study was conducted to study the time of water imbibition required to overcome acacia seed dormancy. A randomized experimental design with four replicates of 50 seeds/treatment was used. In addition to the control, which consisted of intact seeds with no previous treatment, the following treatments were considered: seed immersion in boiling water at 100°C, for 30, 45, 60 and 75 seconds; subsequently, half the seeds were maintained immersed for 12 hours in ambient (27°C) water, totalizing nine treatments. After that, the seeds were incubated at 25°C, constant temperature, inside a plastic gearbox with moistened germitest filter paper as substrate and maintained in germination chambers during assessment. Through regular assessment, the parameters germination, imbibition and number of normal seedlings after 18 days were determined. The daily counting of germinated seeds took place for 18 days. The results show that maximum seedling emergence was obtained in 100 oC water, without posterior immersion in ambient water; this temperature and the period of 1 minute are remarkable, as they present the highest germination and represent operational standardization as a method to be utilized in Acacia mangium seed procedures to overcome the tegument hardness of this species.

Avaliação de cultivares de girassol em savana de Roraima

Sunflower (Helianthus annuus L.) can be cultivated at different times of the year. Hence, this oilseed crop stands out among the viable crops to be explored in the savanna area of Roraima. However, cultivars can perform differently depending on the region they are grown. Accounting on this, a study was carried out to evaluate the effect of sowing time for this crop in Boa Vista, Roraima, utilizing six cultivars (Agrobel 910; Agrobel 920; Cargill 11; Embrapa 122; Morgan 742; and Rumbosol 91) in a split-plot scheme, in a randomized complete blocks design, with two plots (sowing time: January 20, with supplementation of water, and July 19). The sub-plots consisted of four rows, measuring 6 m each, distanciated 0.90 m; the distance between plants inside the row was 0,30 m. The cultivars cargill 11, rumbosol 91 and agrobel 910 were the most productive for cultivation in the savanna ecosystem in Roraima. The sowing of sunflower in January was more appropriate than July.

Formas de aplicação de nitrogênio em três cultivares de girassol na savana de Roraima

, nao havendo superioridade dos hibridos Agrobel 960 e Ag robel 962 em relacao a variedade Embrapa 122/V2000. Palavras-chave - Helianthus annuus L. Adubacao Nitrogenada. Savana. Plantas-efeito nitrogenio. Abstract - Nitrogen is the nutrient that limits most the production in the culture of sunflower (Helianthus annuus L). The nutritional requirements among cultivars of the same species is distinct, under the same conditions of culture and for the same agricultural year. With the objective of evaluating four different ways of nitrogen application in the production components of different genotypes of sunflower, an experiment was carried out in a randomized block design in a 3 x 4 factorial scheme (genotypes x ways of nitrogen applying) with four replicates . The treatments consisted on the combination of three varieties: Agrobel 960, Agrobel 962 and V - 2000 and four different ways of nitrogen application: 100% at 20 days after sowing (DAS) - (0-100-0-0); 30% at sowing and 70% at 20 DAS - (30-70-0-0); 30% at sowing, 30% at 20 DAS e 40% at 40 DAS (30-30-40-0); 20% at sowing, 30% at 20 DAS, 30% at 40 DAS e 20% at 60 DAS (20-30-30-20). Measured variables were: height of the plant, height of the capitulum, diameter of the stem, diameter of the capitulum and achene yield. The ways of nitrogen application affected all components of yield. The N formulation (30-70-0-0) has determined the best results for the variables studied, but the form (30-30-40-0) provided results comparable to treatment (30-70- 0-0); treatments where N was applied as (20-30-30-20) caused decrease in the performance of sunflower for all variables. The varietal effect was observed only for plant height and height of the capitulum. The highest yield of achene achieved was 1.639 kg ha-1, with no superiority for the hybrids Agrobel 960 and 962 in relation to the variety 122/V2000 Embrapa.

Tratamento inseticida e qualidade de sementes de milho durante o armazenamento

To study the effects of insecticides (deltamethrin, chlorpyrifos, phosphin, and diatomaceous earth) on the insect control of stored corn seeds during 12 months, this research was performed to find an alternative product, using a randomized design. Seeds of the hybrid AG 303 were treated with either isolated or combined deltamethrin and chlorpyrifos, phosphin and diatomaceous earth, and they were further arranged into multifoliated paper bags and stored for twelve months (May/1997 through April/1998) under normal environmental conditions. Seeds were submitted to an infested seed exam, mass of 100 seeds, germination test, cold test, accelerated aging, electric conductivity test, emergence of seedlings in field and rate of seedling emergence, seven times in bimonthly intervals. Interpretation of the results showed that: deltamethrin and chlorpyrifos insecticides (alone or combined), phosphin and diatomaceous earth promoted the control in a similar manner, of pest-insects occuring during storage without causing toxicity to corn seeds. The physiological quality of corn seeds was effectively preserved by the addition of chemical insecticides and diatomaceous earth.

Épocas de colheita e qualidade fisiológica das sementes de arroz irrigado cultivar BRS 7 TAIM, em Roraima

Harvesting time is one of most important factors which influence rice seed characteristics for the purpose of planting or milling. With the objective to determine the proper period of harvesting of irrigated rice (Oryza sativa L.) the seeds of BRS 7 TAIM cultivar were harvested at at 15, 22, 29, 36, 43 and 50 days after flowering, dryed, processed for cleaning purpose and evaluated in relation to moisture, productivity, dry weight of 100 seeds, undamaged rice yield, viability and storability. Seeds harvested at 15 and 22 days after flowering showed low performance exhibiting deficiency in all variables studied, besides high initial humidity. Seeds harvested at 29 days showed hight quality, but yield was lower than those of later periods. Those obtained from harvest at 50 days showed good performance, with exception for undamaged rice yield. The best harvesting period considering TAIM cultivar is between 38 an 42 days after flowering, when seeds present high rates of quality, yield, dry weight, undamaged rice yield, physiological quality and storability.

População microbiana em solo cultivado com soja e tratado com diferentes herbicidas em área de cerrado no estado de Roraima

This work aimed to evaluate the impact of glyphosate, imazaquin and trifluralin on soil microbial biomass, on bacteria community associated with soybean rhizoplane and soybean nodulation under two different agricultural management: no-tillage (SD) and conventional tillage (SC). The results showed that imazaquin in SD area lead a significant reduction of soil microbial biomass during the period of evaluation (60 days) and, also had greater modifications in bacterial DGGE profile than the glyphosate treatment. There was no significant effect of herbicides on microbial biomass in SC area, and DGGE profiles presented high variability among replicates of the same treatments, which had difficult the observation of herbicides effects. Some fragments excised from DGGE gels and sequenced indicate that glyphosate interfered in the development of a bacterium with 90% of homology to Herbaspirillum sp. 16S rDNA, while another with 96% of homology to Ralstonia sp. 16S rDNA was greatly present only in imazaquin treatment, and some others bacteria with more than 92% of homology like Burkholderia, Thiomonas and Pseudomonas were not affected by herbicides. Besides that, no significant effect of the herbicides occurred on soybean nodulation.

Qualidade de sementes de soja BRS Tracajá, colhidas em Roraima em função do tamanho no armazenamento

The main goal of this study was to evaluate the physical and physiological quality of soybean seeds, cultivar BRS Tracaja, harvested in savanna (cerrado) area of the State of Roraima according to size and storage. The seeds were cleaned and manually classified by size, using three sieves with round holes with dimensions: 5.5; 6.0 and 6.5 mm, subsequently disposed in proper paper bags and stored during six months under conditions of temperature (23 °C) and air relative humidity (60%) at Embrapa Roraimas seed laboratory. The seed quality was evaluated in the beginning of storage and after 2; 4 and 6 months of storage according to the thousand seeds weight test, germination, first germination count, electrical conductivity, field seedling emergence, speed of seedling emergence in the field, seedling dry weight and dry weight per seedling. The results show that the size influences physical and physiological quality of seeds from cultivar BRS Tracaja during storage. Seeds of higher sizes from cultivar Tracaja (6.5 mm) present higher value in the thousand seeds weight test. The highest percentages of germination and vigor through seeds electrical conductivity test, concerning seeds of BRS Tracaja cultivar, during storage, were obtained among seeds of larger sizes (6.0 and 6.5 mm). Seeds with larger sizes from BRS Tracaja (6.0 and 6.5 mm) showed during storage, the highest percentage of field seedling emergence and the seeds with smaller sizes (5.5 mm), the smallest rates of field speed of seedling emergence.

Compatibilidade do tratamento de sementes de feijão-caupi com fungicidas e inoculação com estirpes de Bradyrhizobium

The objective of this work was to evaluate the compatibility of seed treatment with fungicides and Bradyrhizobium strains inoculation for cowpea. Cell survival on seeds of cultivar BRS Guariba treated or not with fungicides (fludioxonil, carbendazim, carbendazim + thiram, and carboxin + thiram) and inoculated or not with Bradyrhizobium (strains UFLA3-84, BR 3267, INPA3-11B, and BR 3262) were evaluated in laboratory. Another experiment was carried out in greenhouse, in Leonard jars, using the same treatments. The following were evaluated: shoot dry matter weight, besides number and dry matter weight of nodules 25 days after plant emergence. Two experiments were performed in the field with the strain BR 3262, with fungicides on the seeds: one in a first cultivation area and the other in an area previously cultivated with annual crops. Nodule number, nodule dry weight, and shoot dry matter weight were evaluated at 35 days, and grain yield at harvest. Fungicides did not have significant effect on Bradyrhizobium survival, plant nodulation, and grain yield, which was, in average, higher than 1,200 kg ha-1. Cowpea seed treatment with fungicides is compatible with the inoculation of the evaluated strains.

Superação da dormência em SementeS de paricarana (Bowdichia virgilioides Kunth.) 1

Dormancy is a phenomenon in which seeds of a species do not germinate, even when they are viable and environmental conditions are suitable. The objective of this study was to assess the effects on seeds of different periods of immersion in boiling water, with or without posterior immersion in sodium hypochlorite, on the alleviation of paricarana (Bowdichia virgilioides Kunth.) seed dormancy. Seeds were previously homogenized and separated according to size and color, with red-colored seeds being used. The treatments applied were: T1 = immersion in water at 100 °C for one second; T2 = immersion in water at 100 °C for 10 seconds; T3 = T2 + posterior immersion in 2.5% sodium hypochlorite for 1 minute; T4 = immersion in water at 100 °C for 20 seconds; T5 = T4 + immersion in 2.5% sodium hypochlorite for 1 minute. Each treatment consisted of four replicates of 50 seeds. The highest emergence scores were obtained with seed immersion in water at 100 °C for 10 seconds, with or without the posterior use of sodium hypochlorite. This is the recommended procedure for breaking the seed tegument dormancy of paricarana (B. virgilioides). Immersion of paricarana seeds in sodium hypochlorite for one minute, after seed immersion in water, facilitates imbibition and reduces seed deterioration.

POTENCIAL FISIOLÓGICO DE SEMENTES DE GENÓTIPOS DE SOJA PRODUZIDOS EM DIFERENTES AMBIENTES DE CERRADO EM RORAIMA

Several factors can determine the physiological quality of the seeds, among them we can highlight the genotype caused by the physiological maturation, defined by the weight of dry mass, germination and vigor. The objective was to determine the physiological potential of soybean genotype seeds produced in three cultivation ENCICLOPÉDIA BIOSFERA, Centro Científico Conhecer Goiânia, v.15 n.27; p. 2018 232 environments in the cerrado of Roraima. The experiments were carried out in three environments in the cerrado of Roraima and in the Laboratory of Seed Analysis (LAS) of Embrapa Roraima in 2017. Soybean seeds of thirty five genotypes produced in three environments were evaluated (Água boa experimental field / Embrapa RR AB, Fazenda Livramento FL, Fazenda São Pedro FSP) for evaluation of mass of 1000 seeds, productivity, first germination count, germination test, emergence of field seedlings, field emergence velocity and electrical conductivity. The design used in the field was in blocks and in the laboratory was completely randomized formed by the factorial scheme (3x35). The data obtained from the measured variables were submitted to analysis of variance with application of the Scott-Knott test for different genotypes and Tukeys test for different environments at 5% probability. It was verified that there was significant interaction at 5% of probability between environments and the analyzed genotypes. For the variables measured, M. Soy 8372 IPRO produces seeds with greater vigor in the Água Boa environment, while BRASBT13-0225 in Farm Livramento environment, and Sambaiba 05 IPRO in the environment Farm Saint Peter. None of the 35 genotypes present greater vigor in the three environments. The Farm Livramento environment produces more seeds and less vigor.