A. A. Henning

Qualidade fisiológica, física e sanitária de sementes de soja produzidas no Brasil

Nos ultimos anos, o Brasil tem apresentado desempenho crescente em termos de produtividade e producao de soja. Todavia, alguns estudos mostram que a falta de controle de qualidade tem comprometido a germinacao e o vigor de parte significativa de sementes de diferentes genotipos. Com base nessa realidade, foi conduzido um estudo, objetivando dimensionar e avaliar os aspectos da qualidade de sementes da soja em diferentes regioes produtoras do Brasil. Na safra agricola 1997/98, foram coletadas 331 amostras nos estados do Parana, Minas Gerais, Goias e Rio Grande do Sul. Para a analise da qualidade foram empregados os seguintes parâmetros: germinacao, vigor (TZ 1-3), viabilidade (TZ 6-8), deterioracao por umidade (TZ 6-8), lesoes de percevejos (TZ 6-8), sementes quebradas, ruptura de tegumento, dano mecânico (TZ 6-8) e sanidade (blotter test). A analise estatistica dos resultados mostrou reducao acentuada da germinacao e do vigor, em funcao dos altos niveis de deterioracao por umidade, de lesoes de percevejos, de quebras, de ruptura de tegumento e de injuria mecânica, no norte e oeste do Parana, Goias e Minas Gerais, quando comparados com o sul do Parana e Rio Grande do Sul. Estas ultimas regioes apresentaram baixos indices de deterioracao por umidade e de lesoes de percevejo. Ainda foi observado que a incidencia de certos patogenos, em sementes de algumas regioes, nao chegou a comprometer a germinacao e o vigor das diferentes cultivares avaliadas. De uma maneira geral, as sementes produzidas na regiao sul do Parana e no Rio Grande do Sul apresentaram um melhor padrao de qualidade quando comparadas com as demais regioes estudadas.

Pre-harvest desiccation: effects on the physiological quality of soybean seed.

Temperature fluctuations associated with high rainfall and the oscillating relative humidity of the air during the pre-harvest stages of seed maturation may result in losses in physical and physiological quality and also in seed health. Pre-harvest desiccant application helps to reduces seed exposure to unfavourable climate conditions and reduce seed vigor and germination. The object of this research was to determine the effects of the application period of desiccants and of early harvesting on soybean seed quality. The experiments were conducted in Alto Garcas, MT, with the cultivars MG/BR-46 Conquista and FMT Tucunare in the 2005/2006 growing season, and with BRS MT Pintado and FMT Tucunare in 2006/2007. The experimental design was a randomized block in a factorial arrangement 6x2x2x2 [6 treatments (5 desiccants and 1 control), 2 application times, 2 harvest times and 2 storage periods]. Five desiccant treatments were evaluated: paraquat, diquat, paraquat + diquat, paraquat + diuron and glyphosate, applied at the R6.5 and R7 growing stages, which were compared to a control treatment. Seeds were harvested at two stages: first, when moisture content reached 17% to 20% (early harvest), and secondly, 12% to 13% (normal harvest). Seeds from early harvesting were dried to 12% to 12.5% moisture content in a forced air chamber at temperatures ranging from 38 oC to 40 oC. Seed quality was evaluated by the following tests: germination, seedling vigor classification, tetrazolium, field seedling emergence and seedling growth. Paraquat, diquat, paraquat + diquat and paraquat + diuron as pre-harvest desiccants do not affect seed physiological quality but glyphosate causes phytotoxic damage to seedling roots. With the exception of glyphosate, pre-harvest desiccation at the R6.5 and R7 growth stages results in the production of seeds having a similar quality. Early harvest results in the production of higher quality seeds compared to those from a normal harvest.

RECOBRIMENTO DE SEMENTES DE SOJA COM MICRONUTRIENTES, FUNGICIDA E POLÍMERO 1

Seed coating is being used to incorporate pesticides, biological hormones, micronutrients and polymers that provide better performance for seeds, seedlings and plants in advanced stages of the crop. The main objective of this study was to evaluate the effect of soybean seed cv. BRS 153 coating on seed quality and seedling performance. Coating was made with three doses of micronutrients: 1; 2 and 4 mL/kg seeds; one fungicide: Derosal Plus® (Carbendazim + Thiram) and a polymer (Laborsan Red Solid Pam Bril® + color agent). Evaluations were made in the laboratory, greenhouse and in the field and consisted of standard germination, first count of germination, accelerated ageing, seedling length, emergence and germination speed index in the greenhouse and field emergence; The results allowed the following conclusions: a) coating soybean seeds with micronutrients, fungicide and polymer provide better uniformity (adherence, distribution and coloration) to the seeds. b) soybean seed coating does not affect its quality and performance up to 2mL micronutrient per kg of seed, if a limit of 6mL final liquid mixture per kg is observed; and c) micronutrient dosage of 4mL/kg seed is phytotoxic when seeds are coated.

AVALIAÇÃO DE METODOLOGIA ALTERNATIVA PARA O TESTE DE TETRAZÓLIO PARA SEMENTES DE SOJA

An alternative method of the tetrazolium test established that the preconditioning period of soybean seeds could be successfully shortened from the traditionally 16 hours at 25oC to 6 hours at 41oC. Since this alternative method has been tested so far with a limited number of soybean cultivars, it is imperative that it should be tested for additional cultivars. The applicability of this alternative procedure of seed preconditioning was tested in ten soybean cultivars: BR-13, EMBRAPA 4, EMBRAPA 48, FT-Abyara, FT-5, IAS 5, OCEPAR-13, OCEPAR-14, OCEPAR-16, and OCEPAR-17. Two imbibition periods (4 h and 6 h) at 41oC were tested and compared to the traditionally recommended period for preconditioning. The following tests were carried out: seed moisture content and tetrazolium through determinations of vigor, viability and level of mechanical damage, weathering and sting bug damage. From the results, the following conclusions can be drawn: a) seed preconditioninig for 6h at 41oC resulted in adequate staining patterns of the seeds, allowing accurate estimates of vigor and viability; b) seed preconditioning for 4 h at 41°C did not develop adequate staining of the seeds, to correctly evaluate vigor and viability of the seeds; however, this procedure was efficient to identify sting bug damage on seeds.

Perfil dos aspectos físicos, fisiológicos e químicos de sementes de soja produzidas em seis regiões do Brasil

A semente de soja, produzida em algumas regioes do Brasil, tem apresentado serios problemas de qualidade fisiologica. Essa situacao pode ser atribuida a ajustes inadequados do sistema de trilha das colhedoras, a ocorrencia de estresses climaticos na maturacao e, geralmente, a lesoes de percevejos, resultando em semente com baixos potenciais de germinacao e de vigor. O estudo teve como objetivo avaliar o comportamento da qualidade da semente produzida em diferentes regioes produtoras de soja e identificar locais com condicoes edafoclimaticas ideais para sua producao com melhor potencial qualitativo. Foram avaliadas 364 amostras de diferentes cultivares de soja, coletadas diretamente do tanque graneleiro das colhedoras, nos estados do Parana, Minas Gerais, Mato Grosso do Sul e Mato Grosso (regiao de Alto Garca). Para diagnosticar o desempenho da qualidade, empregaram-se os seguintes parâmetros: grau de umidade, germinacao, sementes quebradas e testes de hipoclorito e tetrazolio, este para estimar vigor, viabilidade, dano mecânico, deterioracao por umidade e lesoes de percevejos, alem de analise quimica. Os resultados indicaram que indices elevados de danos mecânicos, de quebra e de ruptura de tegumento, quando associados a percentuais acentuados de deterioracao por umidade e de ataque de percevejo afetaram, em maior intensidade, a qualidade da semente proveniente de Minas Gerais, do Mato Grosso do Sul e das regioes norte e oeste do Parana, quando comparados com aquelas oriundas do Estado do Mato Grosso e da regiao sul do Parana. Nos Estados do Mato Grosso e regiao sul do Parana, existem areas com potencial climatico, para producao de sementes de soja com elevada qualidade fisiologica. Existem regioes nos Estados de Minas Gerais, Parana e Mato Grosso que produzem sementes de soja com maiores teores de proteinas e oleo e com acidez relativamente baixa.

Tratamento de semente e aplicação foliar de fungicidas para o controle da ferrugem-da-soja

The objective of this work was to evaluate the effect of soybean seed treatment with fluquinconazole and foliar fungicide application on soybean rust management, in three sowing dates, during the 2007/2008 growing season, in Londrina, PR, Brazil. The experimental design was a randomized complete block, with a factorial arrangement of 2x5 (with two treatments of seeds with fluquinconazole, and five foliar fungicide applications) in the first sowing time, and of 2x6 in the second and third sowing time. The parameters evaluated were: the area under disease progress curve, the normalized difference vegetation index (NDVI) and yield. There was no significant interaction between seed treatment with fluquinconazole and fungicide mixture in foliar applications. Seed treatment with fluquinconazole did not delay the disease progress, and showed no significant difference from treatment without fluquinconazole for sowing time or any other parameter evaluated. The NDVI showed high correlation with disease severity and yield, in all sowing times. Yield response for time and the interval of application varied according to sowing dates and the time of disease onset.

Validação do zoneamento ecológico do estado do Paraná para produção de sementes de soja

This study was carried out to determine the ecological regions most suitable for soybean seed production in the State of Parana, Brazil. At harvest, 121 seed samples of the cultivars BR 16 and 119 samples of BRS 133 were collected from different regions in the state, from 1997 to 2002. Growing season seed quality evaluations were: standard germination and the tetrazolium test for field deterioration, mechanical damage and stink bug attack. Three regions were previously defined based upon mean temperature (MT) in February;:T1 region, with AT>24oC; T2, with AT between 22 and 24oC; and T3, with AT< 22oC. The region T3 produced the best quality seeds followed by regions T2 and T1. Mechanical damage during harvest significantly reduced seed quality, especially in regions T1 and T2. In general, region T3 was the most favorable area for production with high quality seed. Other factors, such as mechanical damage and stink bugs, were responsible for lowering seed quality of two soybean cultivars produced in the State of Parana. Based on the climatic chart of the State of Parana and the results obtained in this trial we can infer that the validation of ecological zoning is a solid alternative for seed producers in the State of Parana to search for suitable areas in which high quality soybean seed production is possible.

Épocas de tratamento de sementes no estabelecimento e desempenho produtivo da cultura da soja

The objective was to assess the early treatment effect of soybean seeds and pre-sowing with different combinations of chemicals on the establishment of plants and crop yield performance. The design was in randomized blocks in a 2x7 factorial arrangement, with two times for seed treatment and seven treatments (six chemical treatments and an untreated control). The treatments were: 1) fipronil + pyraclostrobin + thiophanate methyl; 2) imidacloprid + thiodicarb + carbendazin + thiram; 3) abamectin + thiamethoxam + fludioxonil + mefenoxam + thiabendazole; 4) carbendazin + thiram; 5) fludioxonil + mefenoxam + thiabendazole; 6) carboxin + thiram; and 7) untreated control (water only). The assessments were: seedling emergence, final stand, plant height and insertion of first pod, number of pods per plant, seeds per pod and per plant, thousand-seed weight and grain yield. Early treatment of soybean seeds (240 days prior to sowing) hinders the establishment of the crop, the thousand-seed weight and grain yield in relation to the pre-sowing treatment. Chemical treatments tested containing fungicides and insecticides associated favor the establishment of the crop, but do not alter the soybean yield performance.

Relação entre a permeabilidade da vagem e a qualidade da semente de soja

The aim of this study was to evaluate the influence of pod wall permeability on the physiological quality of soybean seed. The cultivars studied were Sant’Ana, FT-2, FT-10, Bossier, Davis and the breeding line F 84-7-30, with a black seed coat. Pods were collected from plants at the R4, R5, R6, R7 and R8 development stages, which composed the treatments in regard to time of harvest. The parameters of permeability and the lignin content of the pods and the seeds within the pods were evaluated. The seeds were collected just after full maturity (R8), and the following tests were performed: germination, electrical conductivity, and tetrazolium, which determined seed viability and vigor. A randomized complete block design in a split-plot in time arrangement was used, with four replications per treatment. The soybean genotypes (six) composed the plots, and the split-plots consisted of the development stages (R4, R5, R6, R7 and R8). In seed evaluation, the same design was used, reducing the number of treatments to three in the split-plots (R6, R7 and R8). Pod permeability varied with the genotype and stage of development; this affected seed vigor, but not the viability of newly-harvested seeds. The pod lignin content did not show any influence on pod permeability.

Spray volumes in the industrial treatment on the physiological quality of soybean seeds with different levels of vigor

The aim of this work was to evaluate the effect of different spray volumes, via industrial treatment, on the physiological quality of soybean seeds with different levels of vigor. The experimental design was completely randomized in a 2x5 factor scheme, with four replications. Factors consisted in two levels of seed vigor (high and low) and five spray volumes (0, 600, 1200, 1800 and 2400 mL. 100 kg-1). Products used to obtain the volumes were: fungicide (carbendazin + thiram); insecticide (imidacloprid + thiodicarb); nematicide (abamectin); micronutrients (cobalt, molybdenum and zinc); polymer (peridiam); biostimulants (kinetin + gibberellic acid) and inoculum (Bradyrhizobium japonicum). The used cultivars were BRS 360 RR and BRS 1010 IPRO. The physiological seed quality was determined by the following evaluations: germination, first count of the germination test, seedling emergence in sand, emergency speed index, total length of shoot and root of the seedlings. In the different spray volumes, high vigor soybean seeds have higher physiological quality than low vigor seeds. The increased spray volumes in seed treatments reduce the physiological quality of low vigor soybean seeds.