Increased sink capacity enhances C and N assimilation under drought and elevated CO2 conditions in maize

Abstract

The maintenance of rapid growth under conditions of CO 2 enrichment is directly related to the capacity of new leaves to use or store the additional assimilated carbon (C) and nitrogen (N). Under drought conditions, however, less is known about C and N transport in C 4 plants and the contributions of these processes to new foliar growth. We measured the patterns of C and N accumulation in maize (Zea mays L.) seedlings using 13 C and 15 N as tracers in CO 2 climate chambers (380 or 750 µmol mol-1) under a mild drought stress induced with 10% PEG-6000. The drought stress under ambient conditions decreased the biomass production of the maize plants; however, this effect was reduced under elevated CO 2. Compared with the water-stressed maize plants under atmospheric CO 2 , the treatment that combined elevated CO 2 with water stress increased the accumulation of biomass, partitioned more C and N to new leaves as well as enhanced the carbon resource in ageing leaves and the carbon pool in new leaves. However, the C counterflow capability of the roots decreased. The elevated CO 2 increased the time needed for newly acquired N to be present in the roots and increased the proportion of new N in the leaves. The maize plants supported the development of new leaves at elevated CO 2 by altering the transport and remobilization of C and N. Under drought conditions, the increased activity of new leaves in relation to the storage of C and N sustained the enhanced growth of these plants under elevated CO 2 .

Effects of elevated CO2 concentration and experimental warming on morphological, physiological, and biochemical responses of winter wheat under soil water deficiency

“…Additionally, the study found that elevated [CO 2 ] allowed more photosynthetic products to be stored in the form of soluble sugars when winter wheat plants were subjected to water deficiency (Figure 3; Table 4), which may indicate that elevated CO 2 concentrations from 400 mmol mol -1 to 800 mmol mol -1 favored Rubisco carboxylation rather than RuBP regeneration (Xu, 2015) may also partially explain that the biomass was barely affected (Wong, 1990;Zheng et al, 2018). Meanwhile, the nitrogen content in the leaves was not limited by elevated [CO 2 ] and water deficiency, which ensured photosynthesis (Zong and Shangguan, 2016). Furthermore, we also found elevated [CO 2 ] concentrations alleviated photosynthesis probably associated with elevated Rubisco activity as well as the amount of gene expression in RbcL3 and RbcS2 when plant under water deficiency (Parry et al, 2003;Hou et al, 2021).…”

Interacting Effects of CO2, Temperature, and Nitrogen Supply on Photosynthetic, Root Growth, and Nitrogen Allocation of Strawberry at the Fruiting Stage

“…Under elevated CO 2 conditions, the activity and activation of Rubisco (measured as V cmax and V cm-m ) were both decreased and further caused the downregulation of photosynthesis under low nitrogen conditions [40]. The reason for these declines was that prolonged exposure to high concentrations of CO 2 led to decreased levels of transcripts of proteins involved in photosynthesis [41]. Meanwhile, the decreased electron transport components (measured as J max ) limited the improvement of the photosynthetic rate under elevated CO 2 conditions, indicating a low-level activity of the PSII reaction center [42,43].…”

Carbon sink strength of nodules but not other organs modulates photosynthesis of faba bean (Vicia faba) grown under elevated [CO2] and different water supply

“…After the canopies were sealed into the chamber, the soda‐lime trap was started and once [CO 2 ] was approximating zero (trapped by soda lime) after 1 h, 13 CO 2 was generated by the addition of H 2 SO 4 as described elsewhere (Bromand et al , 2001). The 13 CO 2 concentrations were maintained at the chamber growth conditions of the plants, that is, 400 ± 10 or 700 ± 10 ppm, respectively (Palta et al , 1994; Zong & Shangguan, 2016) by continuously adjusting the emission and ventilation of 13 CO 2 inside the chambers. [CO 2 ] inside the chamber was monitored and recorded during the labelling period with an infrared gas analyser (IRGA, Li‐6400; Li‐Cor Inc., Lincoln, NE, USA) (Fig.…”