Influence of Molybdenum doses in inoculation and mineral fertilization in cowpea beans

In some leguminous plants, associations with nitrogen-fixing microorganisms allow their nutrition with nitrogen (N) from the atmosphere. This process is known as Biological Nitrogen Fixation (BNF), where through nitrogenase enzymes, N2 is converted to an available form. This process can replace in part, or in total, nitrogen fertilizers. Cowpea bean is a legume species that is recognized for its high capacity to carry out BNF. In the last decades, studies have encouraged small farmers from north and northeast Brazil to use inoculants with rhizobia species since the results of researches have demonstrated that inoculation is an interesting strategy to improve cowpea production. Considering the specific function of molybdenum (Mo) in the N assimilation, different doses of Mo were tested in this study in order to find doses that could improve and enhance BNF. Therefore, this study aimed to compare nitrogen fertilization and BNF in the N assimilation by plants with different Mo doses. Inoculation was performed with the strains UFLA 03-84 and INPA 03-11B. Doses of Mo were applied in seeds and each pot contained five seeds. Thirty-five days after germination, the plants were analyzed for shoot dry matter and fresh matter, N contents and accumulation, as well as the Soil-Plant Analysis Development (SPAD) Index and nodulation in inoculated plants. The different doses of Mo and also the nodulation treatments did not show significant differences in the contents of N. Plants with N fertilization had significant higher shoot dry matter and root dry matter production, in addition to higher N foliar contents and N accumulation. Therefore, BNF was not as efficient as nitrogen fertilization in the evaluated experimental conditions using cowpea beans

Estimulação do enraizamento de estacas de seringueira (Hevea brasiliensis Muell. Arg.)

Experiment was carried out to evaluate the effect of girdling the stem before taking the cutting, the previous position of the cutting In the stem, and the treatment of the cuttings with IBA plus KOH solution, on rooting of stem cuttings of Hevea brasiliensis. Stem cuttings were taken from three stem positions (base, median, and apical regions) from 12 months old plants. Girdling treatment was done 30 days before takingcutting using a'copper wire. This treatment did not affect rooting. IBA treatment was done using a 200 ppm IBA solution plus KOH, by immerging the base of the cuttings on it by 12 hours. This treatment caused phytotoxic symptons on cutting bases. It was observed a significant difference on the rooting of the cutting according to the cutting origin from the stem. The best rooting was obtained on cuttings taken from the base of the stem. Callus formation was more evident on girdling cuttings and median cuttings of rubber plant.Com o objetivo de verificar o efeito do estrangulamento do caule e do ácido indolbutírico no enraizamento de estacas de plantas jovens de seringueira, foi conduzido este ensaio. As estacas utilizadas foram retiradas da perte basal, mediana e apical, sendo que parte das estacas foram estranguladas com fio de arame abaixo de duas folhas, 30 dias antes do estaqueamento no campo. As estacas tiveram suas bases imersas por 12 horas em água ou em solução com 200 ppm de IBA. Os resultados mostraram que as estacas da posição basal da planta foram as que apresentaram maior porcentagem de enraizamento. 0 estrangulamento na base da estaca não influiu no enraizamento. Aplicação de IBA + KOH causou necrose na base das estacas. Ocorreu formação de calo em 77,7% das estacas aneladas, 66,6%, das medianas e 33,0% das basais