H. A. A. Mascarenhas

Resistência de soja a Nezara viridula e Piezodorus guildinii em condições de campo

The soybean cultivars Parana. Vicoja and Santa Rosa, the line IAC 73-228 and the introductions PI 171451 and PI 229358,e were tsted in Campinas, State of Sao Paulo, Brazil, in relation to the stink bugs Nezara viridula L. and Piezodorus guildinii Westw. The line IAC 73-228 had the least percentage of damaged seed (48,l%) in the superior half of the plant, whereas Parana had the highest (96,8%). The introductions PI-171451 (71,1%) and PI 229358 (79,1%) had intermediate degrees of damaged seeds. This difference in damaged seeds could be due to actual resistance to the stink bugs, to resistance to Nematospora coryli transmitted by these insects or due to host evasion. It has been observed by DAUGHERTY et al. (1964) and LINK & COSTA (1974), that varieties with shorter period from flowering to harvest are less damaged by stink bugs and this would be a case of pseudo resistance called host evasion according to PAINTER (1951). There was a high positive correlation between percentage of seeds damaged and green stems at harvest. This feature could be used for field selection against these insects. There was positive significant correlation between damage and seed size. The seed size may be linked in some way to susceptibility to stink bugs. The damage was higher in the superior half of the plants than in the inferior.

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.

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.

Changes in soybean quality resulting from applications of lime and potassium fertilizer

This experiment was conducted in an acid soil low in available K. The treatments were dolomitic lime rates as the main plots and potassium rates as subplots. The soybean seeds of the cv. IAC-14, were inoculated with Bradyrhizobium japonicum. The results demonstrated that liming increased protein content of the seeds, concentration of N in the leaves and seed weight. However, it reduced the hard seed percentage and seed vigor. The supply of K increased oil content, seed weight, concentration of K in the leaves and diminished protein content and hard seed percentage. Possibly, K fertilization and primarily liming may have increased symbiotic activity in the “rooting zone”, and in this way helped to increase the supply of nutrients such as N to the plants, consequently altered the physiological and nutritional quality of the soybean seeds.

The residual effect of liming and potassium fertilization on the occurrence of fungi in soybean seeds

Estudou-se o efeito residual da adubacao potassica e da calagem sobre a ocorrencia de fungos em sementes de soja. O experimento foi instalado com a cultivar IAC-17, no ano agricola de 1991/92, aplicando doses a lanco de O, 3,5 e 7 t/ha de calcario dolomitico e de 0, 150, 300, 450 e 600 kg/ha de K2O. As sementes colhidas no terceiro ano de cultivo, (1993/94) foram submetidas ao teste de sanidade, pelo metodo do papel de filtro. Observou-se que a calagem reduziu significativamente a incidencia de Phomopsis sp., favorecendo, no entanto, a presenca de Aspergillus sp. e de Fusarium sp.. Embora nao tenham sido detectadas diferencas significativas, nos tratamentos com calagem, verificou-se reducao da incidencia de Cercospora kikuchii, Colltotrichum dematium var. truncata e Peronospora manshurica. Apenas a incidencia de Phomopsis sp. diminuiu significativamente devido a adubacao potassica, sendo menor quando se utilizou a dose de 450 kg/ha de K2O.

Linhagem de soja tolerante a alto teor de manganês

One of the obstacles of agriculture practiced in soil of low fertility is soil acidity and generally involves manganese toxicity in plants. The development of cultivars tolerant to Mn would be beneficial to farmers due to reduction in use of liming and consequently reduction in the cost of production. With this objective a preliminary experiment was conducted in nutrient solution which showed that the breeding line was highly tolerant to Mn. This breeding line originated from the cultivar IAC-Foscarin 31. Both the genotypes were planted in a pot experiment conducted in the greenhouse, in a Red Dusky Latosol soil with high Mn concentration. The results showed that the genotype tolerant had a vigorous vegetative growth attaining a height three times that of the normal genotype and without symptoms of Mn toxicity in the leaves and with roots showing normal colour with nodules. The normal genotype (IAC-Foscarin 31) showed dwarf plants with thick stems and crinkled leaves, typical of Mn toxicity symptoms. The taproot and some secundary roots showed dark coloration showing necroses of the tissue due to Mn toxicity. The concentration of Mn in the above ground parts and roots contained 33 and 15% more concentration than the normal genotype and the quantity of Mn absorbed was also 60 and 46% more than IAC-Foscarin 31 showing that the soybean breeding line is extremely tolerant to high Mn content in the plants.

Study of soyabean lines with a long juvenile period and the release of cultivar IAC-15.

To develop soybean cultivars with high productive capacity and good adaptation to the climatic conditions of the State of Sao Paulo, Brazil, hybridizations were made involving soybean parental material with long juvenile period. Lines were selected and evaluated in preliminary and regional experiments carried out at the experimental stations of the Instituto Agronomico. In order to provide soybean growers with the most productive cultivars, regardless of its origin, simultaneous varietal tests were performed by the Institute Agronomico de Campinas/Coordenadoria de Assistencia Tecnica Integral system in the areas where soybeans are cultivated. In the preliminary experiments a simple lattice design (6 x 6) was utilized whereas, in the regional varietal tests a randomized block design was used with four replications. The release of the soybean cultivar IAC-15 was a result of these regional experiments.

Produção, absorção e extração de nutrientes por linhagem de soja que nodula e que não nodula. I. Efeito do nitrogênio mineral e da inoculação

A pot experiment in the greenhouse was conducted using isolineas D71.93.20 (nodulating) and D71.93.31 (non-nodulating) to study the effect of nitrogen application as side dressing on the dry matter yield at flowering time and seed yield. The treatments consisted of 1) D71.93.30 + inoculante, 2) D71.93.30 + inoculante + N; 3) D71.93.31 and 4) D71.93.31 + N. The nitrogen was applied at the rate of 50 kg/ha of N in the form of ammonium sulphate. The results showed that there were no big differences in the production of dry matter harvested at the time of flowering but the seed production in D71.93.31 was greatly affected by nitrogen deficiency even when nitrogen was side dressed. In D71.93.30 which nodulate there was no response to N applied as side dressing, which was confirmed by concentration of N observed in leaves, seeds and seed yield.