Effects of Nitrogen Fertilizer with Nitrification Inhibitor DMPP (3,4-Dimethylpyrazole phosphate) on Nitrate Accumulation and Quality of Cabbage(Brassica campastris L.ssp. pekinesis)

To assess the effects of N fertilizer ammonium sulphate nitrate [(NH4)2SO4 plus NH4NO3;ASN] with the new nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP)(ASN+DMPP) on yield, nitrate accumulation, and quality of cabbage (Brassica campastrisL. ssp. pekinesis), two field trials were carried out under various soil-climaticconditions in Jinhua City and Xinchang County, Zhejiang Province of China in 2002.Results showed that DMPP could increase the mean yield by+2.0tha-1 in Jinhua, +5.5tha-1 inXinchang, decrease NO3--N content by -9.4% in Jinhua, -7.3% in Xinchang and improvenutritional quality by increasing vitamin C (VC), soluble sugar, K, Fe, Zn contentssignificantly.

Remediation of nutrient-rich waters using the terrestrial plant, Pandanus amaryllifolius Roxb.

Effective control of eutrophication is generally established through the reduction of nutrient loading into waterways and water bodies. An economically viable and ecologically sustainable approach to nutrient pollution control could involve the integration of retention ponds, wetlands and greenways into water management systems. Plants not only play an invaluable role in the assimilation and removal of nutrients, but they also support fauna richness and can be aesthetically pleasing. Pandanus amaryllifolius, a tropical terrestrial plant, was found to establish well in hydrophytic conditions and was highly effective in remediating high nutrient levels in an aquatic environment showing 100% removal of NO^-N up to 200 mg/L in 14 days. Phosphate uptake by the plant was less efficient with 64% of the PO4-P removed at the maximum concentration of 100 mg/L at the end of 6 weeks. With its high NO^-N and PO43--P removal efficiency, P. amaryllifolius depleted the nutrient-rich media and markedly contained the natural colonization of algae. The impediment of algal growth led to improvements in the water quality with significant decreases in turbidity, pH and electrical conductivity. In addition, the plants did not show stress symptoms when grown in high nutrient levels as shown by the changes in their biomass, total soluble proteins and chlorophyll accumulation as well as photochemical efficiency. Thus, P. amaryUifolius is a potential candidate for the mitigation of nutrient pollution in phytoremediation systems in the tropics as the plant requires low maintenance, is tolerant to the natural variability of weather conditions and fluctuating hydro-periods, and exhibit good nutrient removal capabilities.