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Wyszukujesz frazę "phosphorus limitation" wg kryterium: Wszystkie pola


Wyświetlanie 1-3 z 3
Tytuł:
Modelling nitrogen and phosphorus limitation on phytoplankton growth in Narva Bay, South-Eastern Gulf of Finland
Autorzy:
Lessin, G.
Lips, I.
Raudsepp, U.
Powiązania:
https://bibliotekanauki.pl/articles/47604.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
nitrogen
Finland Gulf
numerical modelling
Narva Bay
nutrient limitation
phytoplankton
phosphorus
Opis:
The relative roles of nitrogen and phosphorus in the limitation of phytoplankton growth in Narva Bay, south-eastern Gulf of Finland, were studied by combining the results of numerical modelling and nutrient enrichment experiments.Mo delled biomass-based intracellular nutrient concentrations (nutrient functions) were used to estimate the limiting nutrient in Narva Bay.Nutr ient functions – NF ∈ [0; 1] for nitrogen and PF ∈ [0; 1] for phosphorus – define the dependence of the phytoplankton growth rate on nutrients: NF = PF = 1 corresponds to nonlimitation of phytoplankton growth by nutrients, whereas NF = 0 or PF = 0 to zero growth.T he biotests indicated the response of phytoplankton growth to an increase in nutrient concentration in the surrounding water.Thr ee locations were selected for detailed analyses of temporal variations in the nutrient functions: the offshore station N12, station N8 at the mouth of the River Narva, and coastal station 38.T he biotests were performed at the same stations. NF and PF reached values of 0.9 prior to the spring bloom. With the onset of the spring bloom, NF decreased rapidly and remained below 0.1 in the open part of Narva Bay for the rest of that period.I n the coastal zone, NF was in excess of 0. 1, with a local maximum in the river mouth area. PF decreased to 0.3–0.4 in the open bay after the spring bloom.I n the coastal zone PF remained above 0.4, with a certain increase from the midsummer minimum towards the end of summer.The numerical modelling results clearly show that nitrogen limits phytoplankton growth in Narva Bay.Ph osphorus limitation may occur only for a limited period and over a limited area at the Narva River mouth and other coastal locations.I n general, the biotests backed up the modelling results, the main exception being in the open bay during summer.The model does not account for nitrogen fixation, however.S ince N-fixing cyanobacteria were prevalent in the offshore area, the addition of phosphorus led to enhanced phytoplankton growth at station N12.
Źródło:
Oceanologia; 2007, 49, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of selection for more vigorous seminal roots in two cross populations of oat [Avena sativa L.]
Autorzy:
Gorny, A G
Szolkowska, A
Powiązania:
https://bibliotekanauki.pl/articles/2047233.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
vegetative growth
cross combination
nitrogen limitation
cross population
Avena sativa
root selection
root total length
drought
selection effect
seminal root
phosphorus limitation
oat
water deficit
Opis:
Three steps of multi-stage selection for more vigorous seminal roots were done in two cross combinations of oat. The total length of roots (TRL) was measured in seedlings of the F₂, F₃ and F₄ generations grown in filter-paper rollers. On average, the finally selected F₅ (or F₆) progenies distinguished by 7-11% improved rooting ability than their midparents. Transgressive forms were selected only in one cross combination. Coefficients of realized heritability for TRL were low and ranged from 0.08 to 0.42 indicatinga relatively high proportion of non-additive gene effects in the variance of TRL. Tolerance of the F₆-progenies to water and nutrient limitations was evaluated in pot and field experiments. Correlated selection effects were dependent upon initial cross combination. Only progenies from one cross combination exhibited an improved drought tolerance at the 8-9 Feekes' stage. The both enhanced rooting and decreased S : R ratio of the F₆-progenies correlated with their improved tolerance to reduced P supply at the 4-leaf stage. However, no significant consistence occurred between indices of the tolerance to reduced nutrition at the vegetative growth and those at field maturity. Performed root selection identified more frequently high yielding genotypes with less stable grain yield. No progenies were obtained that outperform their parents under low-input conditions. It was emphasized that root selection should be accompanied by selection for integrated response components.
Źródło:
Journal of Applied Genetics; 1996, 37, 4; 331-344
1234-1983
Pojawia się w:
Journal of Applied Genetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rola krzemu w procesie eutrofizacji wód na przykładzie zbiorników Solina i Myczkowce
The Role of Silicon in the Process of Eutrophication of the Waters – Solina and Myczkowce Reservoirs Case Study
Autorzy:
Koszelnik, P.
Powiązania:
https://bibliotekanauki.pl/articles/1819150.pdf
Data publikacji:
2013
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
proces eutrofizacji wód
rola krzemu
nutrient limitation
dissolved silicate
retention
nitrogen
phosphorus
lake
transport
sediments
complex
river
Opis:
This paper reports on studies conducted during 2005–2006 years in the ecosystem of the Solina-Myczkowce mountain complex of mesotrophic reservoirs on the San River, SE Poland. The goal of the present study has been to analyse the functioning of the reservoirs as a dissolved silicon sink especially whether silicon assumes a limiting role where the biological productivity of reservoirs waters is concerned. Silicon is one of the biosphere’s most abundant elements, and one that – in the form of dissolved silica – serves as a very important nutrient playing a major role in the functioning of marine, coastal and inland waters. Investigations indicate that reservoirs are major sinks for the dissolved silica in a river system and that unfavorable changes in water chemistry downstream may ensue where (as is usually the case), the water discharged from a reservoir is poorer in Si than that supplied to it. The noted Si depletion in both the analysed reservoirs influenced growth of non-siliceous algae expressed in terms of chl a. Siliceous algal growth is usually observed there during spring. I suppose that the first chl a maximum in the case of the Solina Reservoir, and the only maximum in the Myczkowce Reservoir, result from the growth of both siliceous and green algae. The next increase in chl a – observed only in the Solina Reservoir – may result from the presence of the cyanobacteria often observed in warm lakes at the end of summer. Their absence from Myczkowce reflects the low temperature of that reservoir’s water, this being supplied from the hypolimnion of the upper one. These observations are confirmed in relationships between mean measured concentrations of Si and mean concentrations of chl a in the euphotic zone of the two reservoirs. Observed summer depletion of the silicate accelerates the growth of phytoplankton exponentially, especially in the case of the upper reservoir.
Źródło:
Rocznik Ochrona Środowiska; 2013, Tom 15, cz. 3; 2218-2231
1506-218X
Pojawia się w:
Rocznik Ochrona Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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