Use efficiency of controlled release fertilizer on the growth of croton and petunia and N loss by leaching

The market of flowers and ornamentals such as croton (Codiaeum variegatum) and petunia (Petunia×hybrida Vilm.-Andr) have been created new technologies to constantly development, as one of the most promising segments of horticulture. Fertilization providing adequate nutrition and less leaching to the environment is the objective of numerous studies around the world. Therefore, two studies were conducted to evaluate the use of controlled release fertilizer (CRF) on the growth of two ornamental species, and N loss by leaching. The first experiment aim to evaluate sources and rates of CRF and water soluble fertilizer (WSF) on croton growth and nitrogen concentration on drained solution. Results showed that treatments with WSF and low rates of CRF provided higher plants growth, and the amount of N leached was higher for WSF treatments. The second experiment objective to compare plant performance and cost for strategies that potentially provide adequate nutrition during both the production and consumer phases for container-grown Petunia plants. In addition, two experiments were conducted to evaluate nutrient release in sand containers inside of the greenhouse and under controlled temperature conditions without plants. Results showed that during production phase all fertilizer treatments produced high quality plants, and during consumer phase, plants grown with WSF only during the production phase were nutrient-deficient, while plants receiving CRFs were still growing vigorously, especially in a high rate. The release rates of all CRF products were temperature-dependent. In conclusion CRF provided plant growth at the same rate that WSF, with less N leaching and extra cost less than U$0.065 per plant with CRF during production.

Plant species, biomass and environmental characteristics of relevés along the North America Arctic bioclimate gradient

Question: How do interactions between the physical environment and biotic properties of vegetation influence the formation of small patterned-ground features along the Arctic bioclimate gradient? Location: At 68° to 78°N: six locations along the Dalton Highway in arctic Alaska and three in Canada (Banks Island, Prince Patrick Island and Ellef Ringnes Island). Methods: We analysed floristic and structural vegetation, biomass and abiotic data (soil chemical and physical parameters, the n-factor [a soil thermal index] and spectral information [NDVI, LAI]) on 147 microhabitat releves of zonalpatterned-ground features. Using mapping, table analysis (JUICE) and ordination techniques (NMDS). Results: Table analysis using JUICE and the phi-coefficient to identify diagnostic species revealed clear groups of diagnostic plant taxa in four of the five zonal vegetation complexes. Plant communities and zonal complexes were generally well separated in the NMDS ordination. The Alaska and Canada communities were spatially separated in the ordination because of different glacial histories and location in separate floristic provinces, but there was no single controlling environmental gradient. Vegetation structure, particularly that of bryophytes and total biomass, strongly affected thermal properties of the soils. Patterned-ground complexes with the largest thermal differential between the patterned-ground features and the surrounding vegetation exhibited the clearest patterned-ground morphologies.