Gerusa Massuquini Conceição

Temperaturas de secagem na integridade física, qualidade fisiológica e composição química de sementes de arroz

The drying of seeds is essential for its production process , however, the temperature used can affect seeds quality . T his study aimed at evaluating the effect of different temperatures on physical integrity, physiological quality and chemical composition of rice seeds. Four lots were arranged for each cultivar, being dried with the aid of the stationary method, by using the following temperatures: 32oC, 38oC, 44oC and 50oC. After each drying treatment, the physical integrity of seeds was analyzed, by evaluating its moisture content and fissures percentage. Physiological quality was evaluated with the aid of the germination test, first counting, electrical conductivity, accelerated aging, cold test, total length and dry mass of seedlings. The chemical composition of seeds was determined by evaluating their dry mass, crude protein and fiber and ethereal extract. The drying temperatures affected seeds quality, and when they increased ( 32-50 oC), the percentage of fissures in irrigated rice seeds also increased. Drying t emperatures of 32 oC and 38 oC allowed the expression of seed quality , while the temperature of 50 oC reduced its physiological potential .

Teste de lixiviação de potássio para a avaliação do vigor de sementes de arroz

The aim of this study was to determine the conditions of the potassium leaching test for evaluating rice seed vigor. Five seed lots of the IRGA 424 variety and five seed lots of the Puita Inta CL variety were tested, and results compared with those from germination tests, first germination count, cold test (without soil), electrical conductivity and seedling germination in the field. The amount of potassium leachate was determined using a flame photometer, after 30, 60, 90, 120, 150 and 180 minutes of immersing 50 seeds in distilled and deionised water at volumes of 20 and 50 mL at 25 oC. The combination of 50 pure seeds submerged in 50 mL of distilled and deionized water at 25 oC for 60 minutes was the most efficient procedure for classifying the physiological quality of rice seed lots.

Redução populacional de trigo no rendimento e na qualidade fisiológica das sementes

Na producao de sementes de trigo diversos fatores (bioticos e abioticos) podem alterar o rendimento e a qualidade de sementes, dentre esses cita-se o estabelecimento adequado das plantas no campo. Dessa forma, objetivou-se com esse trabalho verificar o efeito da reducao da populacao de trigo de forma aleatoria no rendimento e na qualidade fisiologica das sementes produzidas. O estudo foi realizado nas cultivares Horizonte, Marfim, Mirante e Quartzo. Anteriormente a fase do afilhamento, procedeu-se a retirada de plantas de maneira aleatoria nas intensidades de 0; 20; 40 e 60% em relacao a populacao original (350 plantas por metro quadrado). Apos a colheita, avaliou-se o rendimento e a qualidade das sementes produzidas, por meio dos testes de germinacao, envelhecimento acelerado, condutividade eletrica massal e massa de mil sementes. Verificou-se que as cultivares apresentam desempenho diferente quando submetidas a reducoes aleatorias de plantas demonstrando capacidades distintas em compensar eventuais falhas na semeadura. A resposta para rendimento de trigo em funcao da reducao aleatoria na populacao de plantas varia conforme o genotipo utilizado. Quanto a qualidade das sementes produzidas, reducoes aleatoria de plantas de trigo afetam negativamente a qualidade fisiologica das sementes.

Contribution of nitrogen derived from mineral supplementation for soybean seedlings

Seeds can absorb N from mineral supplementation, thus stimulating seedling development in soybeans (Glycine max (L.) Merrill). This study aimed to evaluate the contribution to soybean seedlings of N derived from mineral supplementation in seeds with different nutritional contents. Seeds of the cultivar BMX Potência RR received mineral supplementation enriched with 2.5% excess 15N. The treatments were performed in seeds in two lots, one with high and one with low nutritional content. At 2, 6 and 10 days after sowing on paper towels, the seedlings were collected and separated into cotyledons, roots and shoots. Dry matter production, root length and root volume were assessed. Total N and 15N values were analyzed in the seedling organ tissues. The seeds from the lot with lower nutritional content absorbed more N from the mineral supplement, which was accumulated in the cotyledons and redistributed to the root systems and cotyledons. At 10 days after sowing, most of the N in the organs of soybean seedlings was derived from the seed reserves, regardless of nutritional content. Thus, application of N through mineral supplementation is of low importance for the development and nutrition of seedlings.

Co-inoculation with diazotrophic bacteria in soybeans associated to urea topdressing

O incremento na produtividade de graos pode ser obtido pela interacao entre plantas e microrganismos promotores do crescimento vegetal. Bacterias do genero Bradyrhizobium spp. sao capazes de realizar a fixacao do nitrogenio em soja [Glycine max (L.) Merril], enquanto as do genero Azospirillum spp. induzem a sintese de hormonios vegetais. O objetivo do presente trabalho foi avaliar a inoculacao com Bradyrhizobium e co-inoculacao com Bradyrhizobium + Azospirillum brasilense em sementes de soja associado a aplicacao de 0, 75 e 150 kg de N ha-1 de ureia aplicada em cobertura no estadio reprodutivo. Tres cultivares de soja (BMX Ativa, TEC 6029 e BMX Potencia) foram utilizadas nos experimentos em Santa Maria, RS, Brasil, durante dois anos agricolas (2013/2014 e 2014/2015) e duas epocas de cultivo. Foram avaliadas as caracteristicas morfologicas, de nodulacao e componentes da produtividade. A co-inoculacao proporcionou incremento de 240 kg de graos ha-1 em relacao a inoculacao convencional. Quando co-inoculadas, as cultivares BMX Ativa, TEC 6029 e BMX Potencia acresceram a produtividade de graos em 6, 4 e 12% respectivamente. A aplicacao de 150 kg de N ha-1 acresceu a produtividade em 300 kg de graos ha-1, com a co-inoculacao das cultivares TEC 6029 e BMX Potencia, porem, sem retorno economico. Os cultivares testados quando inoculados somente com Bradyrhizobium nao responderam positivamente a aplicacao de ureia.