Open AccessThe effects of prolonged exposure to elevated temperatures and elevated CO2 levels on the growth, yield and dry matter partitioning of field-sown meadow fescue
Author(s) -
Kaija Hakala,
Timo Mela
Publication year - 1996
Publication title -
agricultural and food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.347
H-Index - 35
eISSN - 1795-1895
pISSN - 1459-6067
DOI - 10.23986/afsci.72747
Subject(s) - tiller (botany) , dry matter , growing season , biomass (ecology) , agronomy , zoology , sowing , field experiment , chemistry , festuca pratensis , yield (engineering) , nitrogen , biology , poaceae , lolium perenne , materials science , organic chemistry , metallurgy
Field-sown meadow fescue (Festuca pratensis, cv. Kalevi) stands were exposed to elevated temperatures (+3°C) and elevated CO2, (700 ppm) levels in two experiments conducted in 1992-1993 (experiment 1) and in 1994-1995 (experiment 2). Total aboveground yield was, on average, 38% higher at elevated than at ambient temperatures. At ambient temperatures elevated CO2 increased the number of tillers by 63% in 1992, 24% in 1993, 90% in 1994 and 14% in 1995. At elevated temperatures, the increase in tiller number in elevated CO2 was seen only in the first growing seasons after sowing. The total yield in a growing season was about 10% higher in elevated CO2 in experiment 1. In experiment 2 the yield was more than 20% higher in elevated CO2 at elevated temperatures, whereas at ambient temperatures the rise in CO2 level had no effect on the yield; the root biomass, however, increased by more than 30%. In elevated CO2 at ambient temperatures the root biomass also increased in experiment I, but at elevated temperatures there was no consistent change. The soluble carbohydrate content of above-ground biomass was 5-48% higher in elevated CO2 at most of the measuring times during the growing season, but the nitrogen content did not show a clear decrease. The reasons for the lack of a marked increase in biomass in elevated CO2 despite a 40-60% increase in photosynthesis are discussed.