Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions

Abstract Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40 °C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively) were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days). After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic). However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity) and carbon release.

Multiplicación en sistemas de inmersión temporal y enraizamiento ex vitro de ocumo blanco (Xanthosoma sagittifolium (L) Schott) / Multiplication in temporary immersion systems and ex vitro rooting of white cocoyam (Xanthosoma sagittifolium (L) Schott)

El ocumo (Xanthosoma sagittifollium (L.) Schott) es una Arácea cultivada en países tropicales debido al valor nutritivo de sus cormos. La principal limitante para su cultivo es la carencia de semilla de calidad, por esta razón se planteó evaluar la multiplicación de brotes de ocumo blanco en sistemas de inmersión temporal, y el enraizamiento ex vitro de los mismos, para lo cual se estudió el tiempo y la frecuencia de inmersión, y la densidad de explantes sobre la proliferación de los brotes. Asimismo, el efecto del ácido indolacético (AIA) y ácido indolbutírico (AIB) sobre el enraizamiento ex vitro de brotes. De acuerdo con los resultados obtenidos, la mayor eficiencia en la proliferación de brotes se obtuvo utilizando el sistema de inmersión temporal del tipo RITA®, con una frecuencia y tiempo de inmersión de 6 veces/día y 5 min, respectivamente, y una densidad de 9 explantes/RITA®. En el enraizamiento ex vitro se determinó que bajo las condiciones de cultivo empleadas no es necesario el uso de auxinas. Se concluye que es posible la multiplicación eficiente de ocumo blanco en sistemas de inmersión temporal, y realizar el enraizamiento ex vitro sin el uso de auxinas.

The white cocoyam (Xanthosoma sagittifollium (L.) Schott), is an Arácea cultivated in tropical countries, due to the nutritional value of its corms. The main limiting factor for cultivation is the lack of healthy seed, by this reason be outlined to evaluate the multiplication of shoots of white cocoyam in temporary immersion systems and the ex vitro rooting of the same. For that which, itself study, the time and frequency of immersion and the density of explants on the proliferation of the shoots. As well as, the effect of the indole acetic acid (IAA) and indole butyric acid (IBA) on ex vitro rooting the shoots was studied. According to the results obtained, the greater efficiency in the proliferation of shoots was obtained utilizing the temporary immersion system of the type RITA®, with a frequency and time of immersion of 6 times/day and 5 min, respectively and a density of 9 explantes/RITA®. In the ex vitro rooting was determined that under the conditions of employed cultivation is not necessary the use of auxins. It is concluded that is possible the efficient multiplication of white cocoyam in temporary immersion systems and to carry out the ex vitro rooting without the use of auxins.

Plant regeneration of Anthurium andreanum cv Rubrun

To establish an efficient regeneration system for Anthurium andreanum cv Rubrun, seeds from plant spadixes were germinated on a medium supplemented with 2.2 muM BA. After 2 weeks, 74 percent of the seeds germinated and four weeks later, micro-cuttings from these plantlets were subcultured on a medium containing 4.4 muM BA and 0.05 muM NAA. On average, 3.6 shoots per explant were obtained. Four weeks old in vitro plants from germinated seeds and the plantlets obtained from micro-cuttings, showed callus proliferation at the stem base. These tissues were subcultured on a medium supplemented with 8.9 muM BA and 2.7 muM NAA. After 6 weeks of culture, about 43.8 plantlets per square cm of callus were obtained. Anatomical studies showed the organogenic nature of these calli. Anthurium andreanum plants regenerated by organogenesis were transferred to pots and a rate of 80 percent of plant acclimatization was obtained.