Roberto Tetsuo Tanaka

Disponibilidade de nutrientes no solo, qualidade de grãos e produtividade da soja em solo adubado com lodo de esgoto

O objetivo deste trabalho foi verificar o efeito direto e residual da adubacao com lodo de esgoto, como fonte de P, na produtividade da soja, na qualidade dos graos para consumo humano e no potencial de lixiviacao do nitrato. O experimento foi realizado no campo e constituiu-se dos seguintes tratamentos: ausencia de adubacao quimica e de lodo; adubacao quimica completa; soja com inoculacao mais dose zero de lodo; soja com inoculacao mais 1,5 t ha-1 de lodo; soja com inoculacao mais 3 t ha-1 de lodo; soja com inoculacao mais 6 t ha-1 de lodo; e soja com inoculacao mais adubacao quimica, exceto a nitrogenada. As maiores produtividades de soja, tanto no primeiro como no segundo ano agricola, foram obtidas nas duas maiores doses de lodo. Os teores de varios elementos nos graos de soja, nos tratamentos com lodo, nao diferiram, significativamente, daqueles obtidos nos tratamentos testemunha ou com adubacao mineral. Perdas de NO3- para o ambiente podem ocorrer, principalmente no periodo inicial do ciclo da cultura.

Influência do magnésio na absorção de manganês e zinco por raízes destacadas de soja

-1 ) x cinco doses de Zn ou Mn (0,5, 1,0, 2,0, 5,0 e 10,0 µmol L -1 ), com tres repeticoes. Com pipetador, foi colocado 14,8 MBq de radiozinco ou de radiomanganes. Apos uma hora de exposicao, as raizes foram lavadas e secadas em estufa; em seguida foram pesadas e determinou-se a radioatividade. Os valores foram convertidos em micromoles por grama de materia seca. Foram estimadas as variaveis Km e Vmax pela equacao de Lineweaver & Burk. As cultivares apresentaram comportamentos distintos na absorcao de Mg, Mn e Zn; a inibicao do Mg sobre o Zn e o Mn na soja e do tipo nao competitiva, e as variaveis Km e Vmax comportaram-se de modo independente no processo de absorcao. Termos para indexacao: Glycine max, nutriente, inibicao, carencia mineral. Magnesium influence on manganese and zinc uptake by excised roots of soybean

Calcário e potássio para a cultura de soja

An experiment was carried out on analic Dark Red Latosol in Mococa, SP, Brazil, during three years, to study the effects of the application of dolomitic limestone (0, 3.5 and 7 t ha-1) and of potassium (0, 150, 300, 450 and 600 kg ha-1 of K2O in the form of KCl ) broadcasted. Two soybean cultivars, IAC-17 and FT-2, of 110 day cycle were utilized, the latter being more demanding for potassium. The results of three crops showed that in the absence of liming there is no response to potassium. Maximum yields were obtained at the rate of 383 and 441 kg ha-1 of K2O, respectively in the presence of 3.5 and 7.0t ha-1 of dolomitic limestone, where the soil ratio (Ca + Mg)/K were in average between 14 and 23. The cv. FT-2 had always a higher yield than IAC-17, except when no potassium was applied. Cultivars FT-2 and IAC-17 produced maximum grain yields of 2384 and 1786 kg ha-1 with the application of 450 and 370 kg ha-1 of K2O, respectively. At the 370 kg ha-1, FT-2 produced a yield of 2354 kg ha-1 of soybean grains, showing that it is more efficient in utilizing the potassium fertilizer in comparison to cultivar IAC-17.

Efeito de adubos potássicos na produção de soja

Um experimento de adubos potassicos (KC1, K2SO4, K-Mag e vinhaca) foi conduzido durante tres anos agricolas em quatro classes de solo: Podzolico Vermelho Amarelo Orto (PV), Latossolo Roxo distrofico (LR), Latossolo Vermelho Escuro textura media (LE) e Latossolo Vermelho Amarelo textura media (LV). Os tres primeiros adubos foram aplicados somente no primeiro cultivo da soja na dose de 150kg/ha de K2O a lanco e incorporados, enquanto a vinhaca foi aplicada anualmente na dose de 50.000 l/ha, um pouco antes de semeadura da soja. Os resultados mostraram que os cultivos sucessivos diminuiram gradativamente os teores de potassio tanto no solo como nas folhas. No segundo ano de cultivo em LV houve respostas positivas da cultura da soja ao uso de potassio, enquanto em PV, no terceiro ano. Entretanto, nao se observaram diferencas entre os adubos. O cultivar IAC-9 mostrou alta capacidade extratora de K como de Ca e Mg.

Boron deficiency in soybeans

Boron deficiency is not usual in soybean crop in Brazil. The observation reported in this article occurred at Guaira, State of Sao Paulo, Brazil on a low flat excessively limed and high in organic matter land. The soil boron content in the areas with plant deficiency was 0.06 ppm while in the areas of apparently healthy plants the soil boron content was 0.11 ppm extracted with boiling water. The leaf concentration for deficient and healthy plants was 10 and 19 ppm respectively. Primary leaves of deficient plants were leathery and thick and there was death of the apical buds. There were few flower formation and pod setting. The boron deficient plants were dwarf with thick stems creating difficulty at harvest and soybean yield was considerably reduced.

Variability in soybean germ plasm for phosphorus uptake and use efficiency for dry matter yield

Twenty nine soybean [Glycine max (L.) Merr.] cultivars were evaluated and classified in relation to the response to P levels in the nutrient solution. P uptake and use efficiency, top and root dry matter yield, P concentrations and contents in plant parts and P efficiency index were estimated. The experiment was set up in a greenhouse, in 1999, in an Experiment Station of the Institute Agronomico, at Campinas, State of Sao Paulo, Brasil, and consisted of a randomized complete block design, arranged in a split-plot, with three replications. The main plots were the P levels in the nutrient solution (0.0645; 0.129; 0.258 and 0.516 mmol. L−1), and the subplots were the 29 soybean cultivars, grouped according to the cycle. The plants were harvested at flowering, separated into tops and roots and processed for dry matter determinations and chemical analysis of nutrients. Plant responses fit quadratic polynomial regression equations. Multivariate analysis showed high correlation among the variables: top and total dry matter (DM), P concentration in tops and P efficiency index (P-EI). Cultivars were classified in efficient-responsive (ER), efficient-non-responsive (ENR), inefficient-responsive (IR) and inefficient-nonresponsive (INR). The ER soybean cultivars showed the highest values for top and total DM and P-EI, and the lowest P-concentrations in the tops.

NITROGÊNIO E POTÁSSIO NA FIXAÇÃO SIMBIÓTICA DE N2 POR SOJA CULTIVADA NO INVERNO

The objective of these experiments was to study the effect of nitrogen and potassium fertilizations on the response to nodulation, nitrogen fixation, nitrogen seed content and yield of two soybean cultivars planted during the winter season. They were installed on the following soils: Eutric Lixisol (Mococa) and Rhodic Ferralsol (Ribeirao Preto and Votuporanga, SP, Brazil). The treatments consisted of three rates of nitrogen (0, 50 and 100 kg.ha-1 of N) as urea, three of potassium (0, 30 and 60 kg.ha-1 of K2O) as chloride and two soybean cultivars (IAC-8 and IAC-14). The experimental design was a random factorial with four replications. Soybean seeds of all treatments were inoculated with a commercial inoculant. At flowering, plants were sampled to evaluate nodulation and nitrogenase activity. At maturity, plants were harvest and seeds weighed.The results showed that inoculation did not provide the amount of nitrogen required to maximize soybean yield in the winter. The nitrogen treatment reduced nodulation and nitrogen fixation, but increased seed yield at the three localities. Potassium fertilization did not have any significant effect on nodulation, nitrogen fixation and yield of soybeans. Increased however dry matter weight and number of nodules of the cultivar IAC-14.

Efeito na produtividade da rotação de culturas de verão e crotalária no inverno

Em ensaio de rotacao de culturas, conduzido em Pindorama, SP, num solo podzolico vermelho amarelo, fase arenosa, durante os anos agricolas de 1991/92, 1992/93 e 1993/94, avaliou-se o efeito da rotacao entre milho, soja e arroz, com e sem crotalaria juncea de inverno, na producao das culturas, no final do terceiro ano da experimentacao. Nao houve diferenca entre tratamentos na producao da soja. A rotacao aumentou a producao de arroz e milho, comparativamente ao monocultivo dessas culturas. A boa produtividade alcancada das culturas no terceiro ano pode ser atribuida, alem da rotacao, a ocorrencia regular de chuvas e ao uso de cultivares tolerantes a acidez

EFEITO DA CALAGEM SOBRE A PRODUTIVIDADE DE GRÃOS, ÓLEO E PROTEÍNA EM CULTIVARES PRECOCES DE SOJA

A study was carried out to evaluate the effects of liming on the yield of four early varieties of soybeans. The experiment was conducted on a Red Yellow Podzolic soil during three years, in which the last two years the residual effect of liming was studied. A split plot design was used, in which the main plots consisted of liming (0, 4, 8 and 12 t/ha) and the sub-plots the early varieties (IAC-13, IAS-5, BR-4 and BR-6). The results showed that independent of varieties, liming increased the soybean yield, decreased the oil content and increased the protein content. Concerning the average of three years, independent of liming levels, the variety BR-4 produced the greatest quantity of oil and protein (444 and 709 kg/ha). The ratio protein/oil was similar among the four cultivars studied.

Crescimento em vasos, de cultivares de soja e de trigo em função da saturação de alumínio

A pot experiment was installed in a greenhouse using an acid sub-soil, classified as a Red Yellow Latosol, shallow phase, high hi aluminum and very low in phosphorus availabilities. The soil acidity was neutralized using calcium hidroxide to reduce the original aluminum saturation of 67 to 45, 30 and 15%. The quantity of subsoil used per pot was 6 kg and 60 kg/ha of P2O5 were applied hi the form of superphosphate. The varieties of soybeans utilized were Biloxi, Davis and Santa Rosa. The results showed that whichever parameter measured (height of the plant, number of nodes, lenght of internodes, number of trifoliate leaves, dry matter weights of shoots and roots) there were no significant differences within each variety for the concentration of aluminum saturation, showing that the three varieties were tolerant to Al. These results were confirmed with two wheat varieties BH-1146 (tolerant to Al) and Siete Cerros (susceptible) which were sown in the same pots. The variety BH-1146 did no show root lenght differences for the Al saturation treaments confirming its tolerance. On the other hand the cultivar Siete Cerros showed increase hi root lenght as the Al saturation was reduced, showing its suscebility.