scholarly journals Laboratory study on the effects of nutrient enrichment on a phytoplankton population in Sawa Lake, Iraq

2008 ◽  
Vol 5 (2) ◽  
pp. 230-236 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Population Dynamics ◽  
Lake Water ◽  
Nutrient Enrichment ◽  
Cell Number ◽  
Shannon Index ◽  
Nitrogen And Phosphorus ◽  
Phytoplankton Population ◽  
Phytoplankton Cell ◽  
Nitrogen Phosphorus ◽  
Index Of Diversity

Nutrient enrichment of Sawa lake water was made using different nitrogen and phosphorus concentrations during autumn and spring at three stations. Different concentrations of nitrogen, phosphorus and N: P ratios were used to test variations in phytoplankton population dynamics. Nitrogen at a concentration of 25 µmole.l-1 and N: P ratio of 10:1 gave highest phytoplankton cell number at all stations and seasons. A total of 64 algal taxa dominated by Bacillariophyceae followed by Cyanophyceae and Chlorophyceae were identified. The values of Shannon index of diversity were more than one in the studied stations.

The interrelation of susceptibility to breakdown, cell size, and nitrogen and phosphorus levels in Jonathan apple fruits

1965 ◽  
Vol 16 (4) ◽  
pp. 617 ◽  
Author(s):  
D Martin ◽  
NS Stenhouse ◽  
TL Lewis ◽  
J Cerny
Keyword(s):  
Nitrogen Content ◽  
Cell Volume ◽  
Negative Relationship ◽  
Dry Weight ◽  
Cell Number ◽  
Nitrogen And Phosphorus ◽  
Individual Tree ◽  
Phosphorus And Potassium ◽  
Low Incidence ◽  
Nitrogen Phosphorus

A block of Jonathan apple trees were treated for 4 years as individual tree plots with nil, nitrogen, nitrogen + phosphorus, and nitrogen + potassium applied as sprays during two periods, either in spring before bud differentiation or after bud differentiation in mid January. The treatments had no effect on the levels of phosphorus or potassium in the fruit. Spring applications had no significant effect on the nitrogen content, but summer applications a marked one, though there was no evidence of a cumulative build-up or any effect on cell number per fruit. These increases in nitrogen content were accompanied by small increases in breakdown level, but only when an inherent seasonal susceptibility existed. Only a diminishing proportion of the additional nitrogen was incorporated into the protein fraction, and the preclimacteric respiration rate was not affected significantly by the increase in protein. Except for percentage dry matter, there was a wide variation in the values between trees of the variables, which permitted a multiple regression analysis. The regression of breakdown and cell volume was positive and highly significant in all years. Except for the year of very low incidence, there was a significant positive relationship between breakdown and nitrogen level, and a consistent negative relationship between breakdown and phosphorus level which was significant in the years of high breakdown incidence. No relationship could be shown between breakdown and potassium. Similar results were obtained by using a percentage fresh weight or percentage dry weight basis for the nitrogen, phosphorus, and potassium contents, or by using actual values or a log (x + 1) transformation for the variables, though there were some advantages in using the latter. The results suggest an important physiological interaction between breakdown and cell volume, nitrogen, and phosphorus.

scholarly journals The SN2 reaction and its relationship with the Walden inversion, the Finkelstein and Menshutkin reactions together with theoretical calculations for the Finkelstein reaction

2021 ◽  
Author(s):  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Linear Models ◽  
Theoretical Calculations ◽  
Computational Method ◽  
Basis Set ◽  
Free Energies ◽  
Nitrogen And Phosphorus ◽  
Atom Pairs ◽  
Leaving Groups ◽  
First Time ◽  
Nitrogen Phosphorus

AbstractThis communication gives an overview of the relationships between four reactions that although related were not always perceived as such: SN2, Walden, Finkelstein, and Menshutkin. Binary interactions (SN2 & Walden, SN2 & Menshutkin, SN2 & Finkelstein, Walden & Menshutkin, Walden & Finkelstein, Menshutkin & Finkelstein) were reported. Carbon, silicon, nitrogen, and phosphorus as central atoms and fluorides, chlorides, bromides, and iodides as lateral atoms were considered. Theoretical calculations provide Gibbs free energies that were analyzed with linear models to obtain the halide contributions. The M06-2x DFT computational method and the 6-311++G(d,p) basis set have been used for all atoms except for iodine where the effective core potential def2-TZVP basis set was used. Concerning the central atom pairs, carbon/silicon vs. nitrogen/phosphorus, we reported here for the first time that the effect of valence expansion was known for Si but not for P. Concerning the lateral halogen atoms, some empirical models including the interaction between F and I as entering and leaving groups explain the Gibbs free energies.

scholarly journals A thermal trade‐off between viral production and degradation drives virus‐phytoplankton population dynamics

2021 ◽  
Author(s):  
David Demory ◽  
Joshua S. Weitz ◽  
Anne‐Claire Baudoux ◽  
Suzanne Touzeau ◽  
Natalie Simon ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Viral Production ◽  
Trade Off ◽  
Phytoplankton Population

scholarly journals Global Landscape of Total Organic Carbon, Nitrogen and Phosphorus in Lake Water

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Ming Chen ◽  
Guangming Zeng ◽  
Jiachao Zhang ◽  
Piao Xu ◽  
Anwei Chen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Total Organic Carbon ◽  
Lake Water ◽  
Nitrogen And Phosphorus

scholarly journals Effects of nitrogen and phosphorus on the abundance and cell size of planktonic nanoflagellate communities

2013 ◽  
Vol 24 (4) ◽  
pp. 427-437
Author(s):  
Danielle Goeldner Pereira ◽  
Fábio Amodêo Lansac-Tôha ◽  
Gustavo Mayer Pauleto ◽  
Luis Mauricio Bini ◽  
Luiz Felipe Machado Velho
Keyword(s):  
Cell Size ◽  
Nutrient Enrichment ◽  
Nitrogen Addition ◽  
Nutrient Addition ◽  
Heterotrophic Nanoflagellates ◽  
Nitrogen And Phosphorus ◽  
Tropical Reservoir ◽  
Pigmented Nanoflagellates ◽  
Density And Biomass ◽  
Nitrogen And Phosphorus Enrichment

AIM: We experimentally investigated the effects of nutrients (Nitrogen and Phosphorus) enrichment on the density, biomass, and cell size of pigmented and heterotrophic plankton nanoflagellates communities. METHODS: The experiment was done in mesocosms in a tropical reservoir during a 19-day period. Four different treatments were carried out: Control (non-nutrient addition - C), phosphorus additions (P), nitrogen addition (N) and phosphorus + nitrogen addition (N + P). Each treatment was performed in triplicate, sorted randomly, thus giving a total of 12 experimental carboys, which were placed transversely in the middle of the reservoir. RESULTS: In general, pigmented and heterotrophic nanoflagellates fractions responded to nutrient addition, increasing densities and biomass values at the fertilized treatments. Opposed to expected, enriched treatments resulted in a slight decrease in mean cell size of the pigmented fraction. Moreover, in nutrient-rich treatments, pigmented nanoflagellates had higher relative abundance than in the control. CONCLUSIONS: Our results indicate that: i) the density and biomass of nanoflagellates responded to the nutrient enrichment, mainly when N and P were added together; ii) the pigmented and heterotrophic fractions showed distinct time responses to fertilization; iii) the growth of nanoflagellate community seems to be co-limited by N and P; iv) the nutrient enrichment led to a greater pigmented than heterotrophic fraction contribution; and v) among the analyzed variables, nanoflagellate densities seem to be more sensitive to changes in nutrient availability than biomass or mean cell size.

Water-Fertilizer Coupling Effects and Efficient Utilization under Peanut-Millet Interplanting Conditions

2013 ◽  
Vol 742 ◽  
pp. 272-277
Author(s):  
Liang Shan Feng ◽  
Zhan Xiang Sun ◽  
Jia Ming Zheng
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Coupling Effect ◽  
Field Capacity ◽  
Nitrogen And Phosphorus ◽  
Application Rates ◽  
Optimal Value ◽  
Factor Interactions ◽  
Nitrogen Phosphorus

In this study, the results showed that water is the most important factor to affect crop yields and optimum soil moisture is lower under the conditions of peanut-and-millet interplanting. Thus, peanut-and-millet interplanting is generally able to fit most of the semi-arid region. In the interaction of various factors, the coupling effect of water and phosphorus was stronger than the coupling effect of fertilizers, following by the coupling effect of water and nitrogen. Among peanuts factors of water, nitrogen, and multi-factorial interaction of water, nitrogen, and phosphorus, water and nitrogen showed a negative effect, whereas the two-factor interactions had a positive effect. There were some differences between peanut and millet in the need for water and fertilizer, in which peanut required more nitrogen and millet needed slightly higher soil moisture and phosphorus. When other factors were in rich level, both of the optimal value for single factors of water, nitrogen, and phosphorus and the optimal value for two-factor interactions of water-nitrogen, water-phosphorus, and nitrogen-phosphorus, were higher than the optimal value for the interaction of water, nitrogen, and phosphorus. The tiny demand difference on moisture in peanut-millet interplanting could be compromised by configuring a reasonable interplanting population structure and the corresponding demand difference on fertilizer could be resolved by uneven crop planting strips. Under the condition of water-nitrogen-phosphorus interaction, the soil moisture content optimal for peanut accounted for 57.3% of the field capacity, and the related appropriate application rates of nitrogen and phosphorus were 0.98 g/pot (81.18 kg/hm2) and 0.39g/pot (32.18 kg/hm2), respectively. Likewise, the soil moisture content optimal for millet was 59.1% of the field capacity, and the counterpart appropriate application rates of nitrogen and phosphorus were 0.57 g/pot (47.03 kg/hm2) and 0.45g / pot (37.13 kg/hm2), respectively.

Distribution of Biomass, Nitrogen, Phosphorus and Other Nutrients in Banksia marginata and B. ornata Shoots of Different Ages After Fire.

1986 ◽  
Vol 34 (6) ◽  
pp. 709 ◽  
Author(s):  
RH Groves ◽  
PJ Hocking ◽  
A Mcmahon
Keyword(s):  
National Park ◽  
Dry Matter ◽  
Lateral Roots ◽  
South Australia ◽  
Distribution Patterns ◽  
Nutrient Accumulation ◽  
Nitrogen And Phosphorus ◽  
Vegetative Organs ◽  
Western Victoria ◽  
Nitrogen Phosphorus

The heathland form of Banksia marginata Cav. regenerates rarely from seed but commonly by resprout- ing from buds on lateral roots, whereas Banksia ornata F. Muell. regenerates only from seed, usually released after fire. The two species co-occur in heath vegetation on nutrient-poor soils in south-eastern South Australia and western Victoria. Shoots were sampled from stands of B. marginata aged from 1 to 25 years and of B. ornata aged from 1 to 50+ years after fire in the Little Desert National Park, western Victoria. B. marginata, the resprouter, distributed a greater proportion of the total shoot dry matter and content of all nutrients to vegetative growth over its shorter life span than B. ornata, the non-sprouter. About 50% of the total phosphorus in B. ornata shoots at 50+ years was present in cones (including seeds) compared with only about 20% in B. marginata shoots at a comparable stage of senescence (25 years). This difference between the species was also true to a lesser degree for nitrogen. There were considerable differences between other nutrients in their distribution patterns in shoots. Nutrients could be grouped together on the basis of distribution in shoots more satisfactorily than on presumed physio- logical roles. Stems were major sites of nutrient accumulation in both species. The content of a particular nutrient in seeds as a proportion of the content in the living parts of the shoot ranged from 0.03% (Na, Mn) to 2.0% (P) in B. marginata, and from 0.3% (Na) to as high as 31% (P) in B. ornata. Concen- trations of all nutrients except sodium were much higher in seeds than in the woody cones or vegetative organs of both species; seeds of B. ornata were particularly rich in calcium and manganese. We conclude that the different patterns of distribution of biomass and nutrients, especially nitrogen and phosphorus, within shoots of the two species reflect their different regenerative modes after fire. Introduction Phosphorus and, to a lesser extent, nitrogen limit the growth of sclerophyllous shrubs on nutrient-poor soils in southern Australia

scholarly journals Effect of Intercropping and Fertility Levels on the Nitrogen, Phosphorus and Potash Content and Uptake by Summer Pearlmillet (Pennisetum glaucum L.) under South Gujarat Condition

2021 ◽  
Vol 9 (3) ◽  
pp. 174-179
Author(s):  
K. R. Patel ◽  
Keyword(s):  
Pearl Millet ◽  
Phosphorus Content ◽  
Pennisetum Glaucum ◽  
P Uptake ◽  
Green Gram ◽  
Treatment Combination ◽  
K Uptake ◽  
Nitrogen And Phosphorus ◽  
College Of Agriculture ◽  
Nitrogen Phosphorus

A field experiment was conducted at College Agronomy Farm, N. M. College of Agriculture, Navsari Agricultural University, Navsari during summer, 2019 and 2020 comprising four intercropping treatments i.e. pearlmillet sole, pearlmillet+greengram, pearlmillet+cowpea, pearlmillet+clusterbean and three fertility levels viz., 75 % RDF, 100 % RDF and 125 % RDF. Among the different intercropping system examined, sole pearl millet (I1) accumulated significantly less content of N and P in pearl millet grain and straw as compared to intercropping with pulses treatments. Pearl millet + green gram (I2) recorded significantly higher N and P uptake by pearl millet straw than other intercropping systems. The sole pearl millet (I1) was at par with pearl millet intercropped with green gram (I2) had significantly higher K content and uptake in pearl millet grain and straw. In case of fertility levels, nitrogen and phosphorus content and uptake in pearl millet grain and straw were recorded significantly higher by application of 100 % RDF. Significantly higher N, P and K uptake by pearl millet grain and straw in pooled results were produced by treatment combination of pearl millet + green gram (I2) intercropping along with 75 % RDF (F1).

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