Influence of elevated carbon dioxide and temperature on belowground carbon allocation and enzyme activities in tropical flooded soil planted with rice

Abstract

Changes in the soil labile carbon fractions and soil biochemical properties to elevated carbon dioxide (CO2) and temperature reflect the changes in the functional capacity of soil ecosystems. The belowground root system and root-derived carbon products are the key factors for the rhizospheric carbon dynamics under elevated CO2 condition. However, the relationship between interactive effects of elevated CO2 and temperature on belowground soil carbon accrual is not very clear. To address this issue, a field experiment was laid out to study the changes of carbon allocation in tropical rice soil (Aeric Endoaquept) under elevated CO2 and elevated CO2 + elevated temperature conditions in open top chambers (OTCs). There were significant increase of root biomass by 39 and 44 % under elevated CO2 and elevated CO2 + temperature compared to ambient condition, respectively. A significant increase (55 %) of total organic carbon in the root exudates under elevated CO2 + temperature was noticed. Carbon dioxide enrichment associated with elevated temperature significantly increased soil labile carbon, microbial biomass carbon, and activities of carbon-transforming enzyme like β-glucosidase. Highly significant correlations were noticed among the different soil enzymes and soil labile carbon fractions.

Short-term response of nitrifier communities and potential nitrification activity to elevated CO2 and temperature interaction in a Chinese paddy field

“…Root biomass and tiller number of wild rice were reported to significantly increase under elevated CO 2 (Inubushi et al, 2003;Kim et al, 2003). Accordingly, increased carbon input in the rhizosphere soil though rice root exudates and rhizodeposition was observed under elevated CO 2 (Bhattacharyya et al, 2013;Okubo et al, 2014). As microbial communities in soil can be generally mediated by carbon substrate availability, an increase in below-ground carbon input could bring changes in soil microbial biomass under climate change conditions (Rakshit et al, 2012).…”

“…Effects had been frequently reported of CO 2 enrichment on rice ecosystem function including rice grain yield and quality, plant nutrients uptake and greenhouse gas emission (Hasegawa et al, 2013;Usui et al, 2014;Tokida et al, 2011). Correspondingly, activity and community composition of ammonia oxidizer in rice rhizosphere could be affected by elevated CO 2 through root exudates and rhizodeposition as well as soil organic carbon (Bhattacharyya et al, 2013;Okubo et al, 2014). The changes to nitrifying activity of agricultural soils under elevated atmospheric CO 2 and warming conditions had been shown to depend on soil pH, inorganic N availability, and ammonia oxidizer community structure and abundance, but these changes were difficult to correlate with those in nitrifying activity (Yao et al, 2011;Long et al, 2012).…”

Effects of Elevated Carbon Dioxide, Elevated Temperature, and Rice Growth Stage on the Community Structure of Rice Root–Associated Bacteria

“…The increase in [CO 2 ] is expected to enhance the growth and yield of C3 crops, including rice (29). Previous studies reported that increases in [CO 2 ] quantitatively and qualitatively altered the release of labile sugars, organic acids, and amino acids from plant roots (2, 6), which may influence the activity of rhizospheric and root–associated microbes, including methanogenesis (18). Tokida et al (32, 33) reported that the emission of CH 4 from paddy fields was significantly increased by [CO 2 ] and/or temperature elevations.…”

Allocation of photosynthestically-fixed carbon in plant and soil during growth of reed (Phragmites australis) in two saline soils

“…High temperatures can inhibit photosynthesis, decrease photosynthesized C fixation and increase photosynthetically-fixed C flow from aboveground to belowground parts (Rennenberg et al 2006;Bhattacharyya et al 2013). However, sufficient soil moisture can offset the negative effect caused by high temperatures (Bassirirad et al 1991;Kuzyakov and Gavrichkova 2010), such as flooded pot conditions during reed growth.…”