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Titolo:
THE RESPONSE OF PERENNIAL RYEGRASS WHITE CLOVER SWARDS TO ELEVATED ATMOSPHERIC CO2 CONCENTRATIONS .1. EFFECTS ON COMPETITION AND SPECIES COMPOSITION AND INTERACTION WITH N SUPPLY/
Autore:
SCHENK U; JAGER HJ; WEIGEL HJ;
Indirizzi:
BUNDESFORSCH ANSTALT LANDWIRTSCHAFT,INST PROD & OKOTOXIKOL,BUNDESALLEE 50 D-38116 BRAUNSCHWEIG GERMANY BUNDESFORSCH ANSTALT LANDWIRTSCHAFT,INST PROD & OKOTOXIKOL D-38116 BRAUNSCHWEIG GERMANY UNIV GIESSEN,INST PFLANZENOKOL D-35392 GIESSEN GERMANY
Titolo Testata:
New phytologist
fascicolo: 1, volume: 135, anno: 1997,
pagine: 67 - 79
SICI:
0028-646X(1997)135:1<67:TROPRW>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
SIMULATED SEASONAL-CHANGES; TRIFOLIUM-REPENS L; WHITE CLOVER; CARBON-DIOXIDE; PLANT-RESPONSES; LOLIUM-PERENNE; MINERAL-NUTRITION; MODEL-ECOSYSTEMS; GROWTH-RESPONSE; PASTURE TURVES;
Keywords:
PERENNIAL RYEGRASS; WHITE CLOVER; ROOT COMPETITION; SHOOT COMPETITION; CO2 ENRICHMENT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
45
Recensione:
Indirizzi per estratti:
Citazione:
U. Schenk et al., "THE RESPONSE OF PERENNIAL RYEGRASS WHITE CLOVER SWARDS TO ELEVATED ATMOSPHERIC CO2 CONCENTRATIONS .1. EFFECTS ON COMPETITION AND SPECIES COMPOSITION AND INTERACTION WITH N SUPPLY/", New phytologist, 135(1), 1997, pp. 67-79

Abstract

The effects of long-term carbon dioxide enrichment on competition fornutrients and light in a ryegrass/clover association were determined for simulated swards of perennial ryegrass (Lolium perenne L. cv. Parcour) and white clover (Trifolium repens L. cv. Karina), which were grown as monocultures and in three mixtures (25/75, 50/50, 75/25), according to the replacement design, at two levels of nitrogen (N) supply (no additional N and 200 kg N ha(-1)) and at season-long ambient (380 ppm) and elevated (670 ppm) CO2 concentrations, in open-top chambers. Stands were cut four times, at about monthly intervals, to a height of 5cm. Plant material was separated into different species, fresh and dry weights were determined and the content of macroelements (N, P, K, S, Mg) in both species was measured. In addition, plant height of both species at harvest dates and during several regrowth periods was monitored. Results indicate that both species made demand on different resources and profited from growth in a mixed sward. CO2-related yield increase amounted to 16-42% for white clover whereas the effect of high CO2 on ryegrass yield ranged between -33% and +9% depending on N supply, mixture and year. As a result the contribution of white clover to total yield in mixed swards was significantly enhanced by CO2 enrichmentat many harvests in both N supply treatments. Without additional N supply, shoot competition for light was intensified by CO2 enrichment tothe disadvantage of ryegrass, since clover petioles grew longer and ryegrass was shorter at elevated CO2. With N fertilization, no marked effect of CO2 enrichment on interspecific competition could be observed. Since clover and total yield were increased by CO2 enrichment, nutrient requirements were also increased and potassium deficiency and increased intraspecific competition of clover for K was observed in the mixtures under elevated CO2 which had the highest nutrient withdrawal. Although white clover profited much more from CO2 enrichment in both N fertilization treatments, the suppression of ryegrass in mixed swards could only be observed under low N conditions. Generally, the effect of N fertilization on competitive interference between both species wasmuch greater than the effect of CO2 enrichment and it is suggested that the effect of elevated CO2 on the balance of species and the outcome of competition in a grass/clover sward is mainly dependent on the N status.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/07/20 alle ore 19:18:21