Dynamic analysis of the impact of free-air CO2 enrichment (FACE) on biomass and N uptake in two contrasting genotypes of rice

Abstract

Elevated CO2 concentrations ([CO2]) in the atmosphere often increase photosynthetic rates and crop yields. However, the degree of the CO2 enhancement varies substantially among cultivars and with growth stage. Here, we examined the responses of two rice cultivars, Wuyunjing23 (WYJ) and IIyou084 (IIY), to two [CO2] (~400 vs ~600) and two nitrogen (N) provision conditions at five growth stages. In general, both seed yield and aboveground biomass were more responsive to elevated [CO2] in IIY than WYJ. However, the responses significantly changed at different N levels and growth stages. At the low N input, yield response to elevated [CO2] was negligible in both cultivars while, at the normal input, yield in IIY was 18.8% higher under elevated [CO2] than ambient [CO2]. Also, responses to elevated [CO2] significantly differed among various growth stages. Elevated [CO2] tended to increase aboveground plant biomass in both cultivars at the panicle initiation (PI) and the heading stages, but this effect was significant only in IIY by the mid-ripening and the grain maturity stages. In contrast, CO2 enhancement of root biomass only occurred in IIY. Elevated [CO2] increased both total N uptake and seed N in IIY but only increased seed N in WYJ, indicating that it enhanced N translocation to seeds in both cultivars but promoted plant N acquisition only in IIY. Root C accumulation and N uptake also exhibited stronger responses in IIY than in WYJ, particularly at the heading stage, which may play a pivotal role in seed filling and seed yield. Our results showed that the more effective use of CO2 in IIY compared with WYJ results in a strong response in root growth, nitrogen uptake, and in yield. These findings suggest that selection of [CO2]-responsive rice cultivars may help optimise the rice yield under future [CO2] scenarios.

Synergetic effects of plastic mulching and nitrogen application rates on grain yield, nitrogen uptake and translocation of maize planted in the Loess Plateau of China

“…There may be two reasons for this: first, the distribution of rainfall in the maize growing season varied considerably between the two years for the same month (Fig. 1 ), and second, CO 2 concentrations in the atmosphere could be another reason for the significant differences in N uptake and NT between the two years 50 .…”

Effects of Elevated Atmospheric CO2 Concentration and Water Regime on Rice Yield, Water Use Efficiency, and Arsenic and Cadmium Accumulation in Grain

“…Sunlight enhances the tilling in rice because it enhances photosynthesis as the seeds' energy reserves are quickly exhausted [43]. Regarding CO 2 atmospheric concentration, in addition to the increase in aboveground biomass resulting from increased photosynthesis [44], higher CO 2 levels also increase root growth [22,23,45]. More roots lead to increased soil nutrients uptake [46], further enhancing tiller production.…”

“…As a C 3 species, rice has lower respiration rates and higher photosynthetic and metabolic efficiencies at high [CO 2 ] levels [21]. For example, a doubling of [CO 2 ] stimulated biomass accumulation of C 3 plants by up to 40% [22]. Root growth and development are also impacted [23], potentially resulting in higher uptake of nutrients and other soil substances.…”

Elevated CO2 enhances rice root growth under alternate wetting and drying irrigation by involving ABA response: Evidence from the seedling stage

“…In addition, the eCO 2 -induced root growth is also associated with the increase in grain yield (Wu et al, 2018;Yang et al, 2008). Those studies suggest that root growth under AWD or eCO 2 is beneficial to increase grain yield.…”