Soybean grown under elevated CO₂ benefits more under low temperature than high temperature stress: Varying response of photosynthetic limitations, leaf metabolites, growth, and seed yield

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• 作者：Guangli Xu^a ; ^b ; Shardendu K. Singh^a ; ^c ; ^{shardendu.singh@ars.usda.gov" class="auth_mail" title="E-mail the corresponding author} ; ^{singh.shardendu@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; Vangimalla R. Reddy^a ; Jinyoung Y. Barnaby^a ; Richard C. Sicher^a ; Tian Li^b
• 关键词：A ; rate of photosynthesis ; Amax ; light-saturated maximum photosynthesis ; Astd ; standardized A estimated at 400  ; μmol  ; mol&minus ; 1Ci ; aCO2 ; ambient CO2 concentration ; eCO2 ; elevated CO2 concentration ; Ca ; atmospheric CO2 concentration ; Cc ; chloroplastic CO2 concentration ; Ci ; sub-stomatal CO2 concentration ; DAP ; days after planting ; Fv&prime ; /Fm&prime ; the quantum efficiency of oxidized (open) PSII reaction centers in the light ; gm ; mesophyll conductance ; gs ; stomatal conductance ; J ; rat
• 刊名：Journal of Plant Physiology
• 出版年：2016
• 出版时间：20 October 2016
• 年：2016
• 卷：205
• 期：Complete
• 页码：20-32
• 全文大小：2118 K

文摘

To evaluate the combined effect of temperature and CO₂ on photosynthetic processes, leaf metabolites and growth, soybean was grown under a controlled environment at low (22/18 °C, LT), optimum (28/24 °C, OT) and high (36/32 °C HT) temperatures under ambient (400 μmol mol⁻¹; aCO₂) or elevated (800 μmol mol⁻¹; eCO₂) CO₂ concentrations during the reproductive stage. In general, the rate of photosynthesis (A), stomatal (g_s) and mesophyll (g_m) conductance, quantum yield of photosystem II, rates of maximum carboxylation (V_Cmax), and electron transport (J) increased with temperature across CO₂ levels. However, compared with OT, the percentage increases in these parameters at HT were lower than the observed decline at LT. The photosynthetic limitation at LT and OT was primarily caused by photo-biochemical processes (49–58%, L_b) followed by stomatal (27–32%, L_s) and mesophyll (15–19%, L_m) limitations. However, at HT, it was primarily caused by L_s (41%) followed by L_b (33%) and L_m (26%). The dominance of L_b at LT and OT was associated with the accumulation of non-structural carbohydrates (e.g., starch) and several organic acids, whereas this accumulation did not occur at HT, indicating increased metabolic activities. Compared with OT, biomass and seed yield declined more at HT than at LT. The eCO₂ treatment compensated for the temperature-stress effects on biomass but only partially compensated for the effects on seed yield, especially at HT. Photosynthetic downregulation at eCO₂ was possibly due to the accumulation of non-structural carbohydrates and the decrease in g_s and A_std (standard A measured at 400 μmol mol⁻¹ sub-stomatal CO₂ concentration), as well as the lack of CO₂ effect on g_m, V_Cmax, and J, and photosynthetic limitation. Thus, the photosynthetic limitation was temperature-dependent and was primarily influenced by the alteration in photo-biochemical processes and metabolic activities. Despite the inconsistent response of photosynthesis (or biomass accumulation) and seed yield, eCO₂ tended to fully or partially compensate for the adverse effect of the respective LT and HT stresses under well-watered and sufficient nutrient conditions.