Effect Of Nutrient Regimes Research Articles

Effect of nutrient regimes on desalination rate and lipid production of Scenedesmus obliquus in saline water

Effect of nutrient regimes on desalination rate and lipid production of Scenedesmus obliquus in saline water

Uptake of weathered p, p′-DDE by plant species effective at accumulating soil elements

Ten plant species previously shown to accumulate inorganic elements effectively from natural solids were grown under field conditions in p,p′-dichlorodiphenyldichloroethane ( p, p′-DDE) contaminated soil. The plant species, which included rye, mustard, canola, vetch, pigeonpea, clover, peanut, and 3 cultivars of white lupin, represented both monocots and dicots, as well as two major families within the dicots: the Brassicaceae and the Fabaceae. The plants varied widely in their ability to phytoextract and translocate weathered p, p′-DDE. The percentage of contaminant phytoextracted ranged from 0.06% (white lupin) to 0.22% (clover, vetch), and the translocation factors (TF; contaminant concentration ratio of stems to roots) ranged from 0.04 (clover, white lupin) to 0.37 (canola). An inverse relationship exists between the amount of contaminant in the roots as measured by the root BCF (bioconcentration factor; dry weight contaminant concentration ratio of root to soil) and the TF. Duplicate mounds of each species were periodically amended with nitrogen (N), phosphorus (P), nitrogen and phosphorus together (N/P); a minus phosphorus treatment involved the addition of AlSO 4 to the soil prior to planting. The effect of nutrient regime on plant biomass, p, p′-DDE uptake and translocation, and inorganic element content varied greatly among the 10 plant species. For some species (rye, vetch, pigeonpea, clover, white lupin), reductions or non-significant changes in p, p′-DDE uptake were observed under the nutrient treatments and were not correlated with plant biomass effects. For mustard, canola, and peanut, the percentage of p, p′-DDE phytoextracted in the various treatments was more than doubled and was directly correlated with a two-fold increase in total plant biomass. Although it is generally assumed that fertilizer amendments will enhance the phytoremediation of organic and inorganic pollutants, the data here suggest that such effects are highly species specific and in some cases may actually decrease remediation potential.

Regional patterns in periphyton accrual and diatom assemblage structure in a heterogeneous nutrient landscape

The effect of nutrient regime on periphyton community development in large rivers was examined (sites ranged from oligotrophic to eutrophic). Patterns in diatom community structure were examined at a large spatial scale (ultimate), whereas at the microhabitat scale (proximate), artificial nutrient-diffusing substrata were used to examine periphyton response to amendment with nitrogen, phosphorus, and N + P. Ratios of ambient dissolved inorganic nitrogen to total phosphorus were used to make predictions of nutrient limitation (molar total inorganic nitrogen (TIN) : total phosphorus (TP)), which matched experimental results in 8 of 12 sites. Two sites with highest ambient nutrient levels (mean NO3 + NO2 and TP, 1.49 and 0.081 mg·L–1, respectively) possessed the highest diatom richness and diversity (mean richness = 42). Lowest diatom taxa richness (19) occurred in an impounded system with low TP (0.008 mg·L–1). Principal components analysis (PCA) of diatom taxa structure among sites (control treatments only) and small-scale patterns among nutrient treatments using all sites and treatments combined indicated that sites were grouped according to drainage basin (r2 = 0.79) and that there was no unified response to enrichment (r2 = 0.43). Results suggest that large spatial scale factors are more important in determining the potential benthic diatom assemblage than small-scale, proximate variables provided by the diffusers.

Yield of sugar beet in relation to weather and nutrients

Data on sugar beet yields from a long-term experiment (1965–1993) at IACR Broom's Barn are used, in conjunction with long-term weather data, to assess the degree to which weather affects yield and how this effect is modified by nutrient availability. Mean temperatures and rainfall during July and August were strongly correlated with sugar beet yields, as well as mean temperature during April and the length of time between sowing and harvest. The data from July and August were entered into a factor analysis to generate two factors describing how hot and dry weather conditions are during July and August. These two factors, as well as April temperature and the length of the growing season, were entered into a multiple regression. The regressions revealed strong effects of the principal axis factors on sugar beet yields across treatments, as well as strong effects of the length of the growing season, but weaker effects of April temperatures. The strength of response to weather was dependent on the nutrient regime, and was, in particular, greater with increased application of nitrogen. There was, however, no effect of nutrient regime on the strength of response of yield to the length of the growing season. These results indicate that weather-induced year-to-year variability in sugar beet yields in unirrigated crops is primarily determined by conditions in July and August as well as the length of time between sowing and harvest, and imply that drought limits yields in well-fertilised crops. The practical implications of these results are that the risk of yield losses due to drought may be minimised by maximising the length of growing season, and that there is the potential for developing simple measures to forecast yields through monitoring of rainfall.

The Effect of Nutrient Regime on Biomass Allocation and Nutrient Accumulation in Red Oak Seedlings

ln Spring 1993, red oaks (Quercus rubra) were propagated from seed. From June through October, plants were fertilized twice daily with 1.4 liters of 20N–10P–20K water-soluble fertilizer solution at concentrations of 0, 25, 50, 100, 200, or 400 ppm N. Destructive harvests were conducted six times at intervals from June through Dec. 1993. Leaf area, stem height, root length, root area, and dry weights of roots, stem, and leaves of harvested plants were measured and tissue nutrient concentrations were analyzed. There was no relationship between whole-plant N concentration and total plant biomass (r = 0). However, there were some linear relationships between total plant N and total plant biomass for an individual fertilizer treatment. Biomass allocation between root, stems, and leaves was very consistent across all fertilizer levels at any one harvest. Percent total N in roots, stems, and leaves also was fairly consistent across fertilizer levels. This was true at each harvest, except the first two, in which a greater percentage of total N was partitioned to the leaves and a smaller percentage was partitioned to the roots in the high (100, 200, 400 ppm N) fertilizer treatments. Whole-plant K concentrations increased with increasing fertilizer level, but decreased over time. Whole-plant P concentrations increased linearly with whole-plant dry weight in the higher (100, 200, 400 ppm N) fertilizer treatments.