Soil and water warming accelerates phenology and down-regulation of leaf photosynthesis of rice plants grown under free-air CO2 enrichment (FACE)

• Published in: Plant and cell physiology Vol. 55; no. 2; pp. 370 - 380
• Main Authors: Adachi, Minaco, Hasegawa, Toshihiro, Fukayama, Hiroshi, Tokida, Takeshi, Sakai, Hidemitsu, Matsunami, Toshinori, Nakamura, Hirofumi, Sameshima, Ryoji, Okada, Masumi
• Format: Journal Article
• Language: English
• Published: Japan Oxford University Press 01-02-2014
• Subjects: Biomass; Carbon Dioxide - metabolism; Carbon Dioxide - pharmacology; Chlorophyll - metabolism; Crops, Agricultural; Edible Grain - growth & development; Edible Grain - physiology; Edible Grain - radiation effects; Japan; Light; Nitrogen - analysis; Nitrogen - metabolism; Oryza - drug effects; Oryza - growth & development; Oryza - physiology; Oryza - radiation effects; Photosynthesis; Plant Leaves - growth & development; Plant Leaves - physiology; Plant Leaves - radiation effects; Plant Stomata - growth & development; Plant Stomata - physiology; Plant Stomata - radiation effects; Plant Transpiration; Ribulose-Bisphosphate Carboxylase - metabolism; Ribulosephosphates - metabolism; Seasons; Soil; Special Focus Issue – Regular Papers; Temperature; Water - physiology; Oryza sativa; Photosynthetic down-regulation; Ecosystem warming; FACE (free-air CO2 enrichment)
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcu005

To enable prediction of future rice production in a changing climate, we need to understand the interactive effects of temperature and elevated [CO2] (E[CO2]). We therefore examined if the effect of E[CO2] on the light-saturated leaf photosynthetic rate (Asat) was affected by soil and water temperature (NT, normal; ET, elevated) under open-field conditions at the rice free-air CO2 enrichment (FACE) facility in Shizukuishi, Japan, in 2007 and 2008. Season-long E[CO2] (+200 µmol mol(-1)) increased Asat by 26%, when averaged over two years, temperature regimes and growth stages. The effect of ET (+2°C) on Asat was not significant at active tillering and heading, but became negative and significant at mid-grain filling; Asat in E[CO2]-ET was higher than in ambient [CO2] (A[CO2])-NT by only 4%. Photosynthetic down-regulation at E[CO2] also became apparent at mid-grain filling; Asat compared at the same [CO2] in the leaf cuvette was significantly lower in plants grown in E[CO2] than in those grown in A[CO2]. The additive effects of E[CO2] and ET decreased Asat by 23% compared with that of A[CO2]-NT plants. Although total crop nitrogen (N) uptake was increased by ET, N allocation to the leaves and to Rubisco was reduced under ET and E[CO2] at mid-grain filling, which resulted in a significant decrease (32%) in the maximum rate of ribulose-1,5-bisphosphate carboxylation on a leaf area basis. Because the change in N allocation was associated with the accelerated phenology in E[CO2]-ET plants, we conclude that soil and water warming accelerates photosynthetic down-regulation at E[CO2].