Influence of photoperiod on the uptake of nitrogen and phosphorus in the water by Eichhornia crassipes and Salvinia auriculata

The main goal of this research was to quantify the concentrations of total and ammonium N, nitrate, total and soluble P in the water in the presence of Eichhornia crassipes and Salvinia auriculata, which were submitted to two different photoperiods in a 24 hours incubation period in the laboratory. The macrophytes were incubated in plastic vials of approximately 1.5 litters, with a previously prepared solution with NH4NO3, NH4Cl, and KH2PO4. Eichhornia crassipes showed the highest average rate of reduction of all the nutrients analysed in relation to Salvinia auriculata. The largest photoperiod reflected in a higher average rate of reduction of nutrients, in both plants. Therefore, we may expect that in some periods of the year (e.g. summer), the aquatic macrophytes would show higher growth rates and higher rates of nitrogen and phosphorus absorption. These results are important for the implementation and management of wastewater treatment systems in tropical areas using aquatic macrophytes

The role of external mycellial network of arbuscular mycorrhizal (am) fungi. II. S study of phosphorus transfer between plants interconnected by a common mycellium

A transferência de 32 p entre Lolium pereme (planta doadora) e plantago lanceolata (planta receptora), mediada por fungos micorrízicos arbusculares (FMA), foi avaliada quando as espécimes cresceram juntas ou separadas. Os resultados demonstraram que a infecçäo micorrízica arbusculares proporcionou aumento significativo na quantidade de 32 P transferida das plantas doadoras para as receptoras näo somente quando as mesmas foram cutivadas com os sistemas radiculares juntos, mas também quando tiveram seus sistemas radiculares separados por uma distância de 2,33 cm. A maior quantidade de 32p transferido entre as duas espécies de plantas ocorreu através da transferência direta via micélio fúngico que as interligou