Elevated CO₂ levels enhance the uptake and metabolism of organic nitrogen

Abstract

The effects of elevated CO (eCO ) on the relative uptake of inorganic and organic nitrogen (N) are unclear. The uptake of different N sources by pak choi (Brassica chinensis L.) seedlings supplied with a mixture of nitrate, glycine and ammonium was studied using N-labelling under ambient CO (aCO ) (350 ppm) or eCO (650 ppm) conditions. N-labelled short-term uptake and N-gas chromatography mass spectrometry (GC-MS) were applied to measure the effects of eCO on glycine uptake and metabolism. Elevated CO increased the shoot biomass by 36% over 15 days, but had little effect on root growth. Over the same period, the N concentrations of shoots and roots were decreased by 30 and 2%, respectively. Elevated CO enhanced the uptake and N contribution of glycine, which accounted for 38-44% and 21-40% of total N uptake in roots and shoots, respectively, while the uptake of nitrate and ammonium was reduced. The increased glycine uptake resulted from the enhanced active uptake and enhanced metabolism in the roots. We conclude that eCO may increase the uptake and contribution of organic N forms to total plant N nutrition. Our findings provide new insights into plant N regulation under eCO conditions.

Plant-Induced Changes to Rhizosphere pH Impact Leaf Accumulation of Lamotrigine but Not Carbamazepine

“…We isolated the effect of nitrogen source-induced rhizosphere pH changes on accumulation of an IOC in plants, a process that we expect also occurs in the field and may become more important if elevated atmospheric CO 2 concentrations promote root exudation of organic acids and shift plant assimilation preferences to reduced nitrogen forms. − We expect our results to serve as a basis for future experimental studies that incorporate more of the complexity that exists in field scenarios. A discussion of how simplifications in our model system may result in differences from what occurs in the field is therefore warranted.…”

Does the short-term fluctuation of mineral element concentrations in the closed hydroponic experimental facilities affect the mineral concentrations in cucumber plants exposed to elevated CO2?

“…In many studies, classical nutrient solution formulations are widely used, such as Hoagland and Arnon, Puppo and Rigaud, and Yamazaki nutrient solution. They were entirely renewed with an update period of 2 to 7 days in many experimental trials (Asensio et al 2015;Bloom et al 2010;Jauregui et al 2017;Li et al 2019;Ma et al 2018;Niu et al 2013;Rodriguez-Hernandez Mdel et al 2014;Vicente et al 2017;Yilmaz et al 2016). The concentrations and proportions of mineral elements in the classical nutrient solution formulations are usually optimized based on the water and mineral demands of plants grown in ambient [CO 2 ] (aCO 2 ) condition, so that they could maintain nearly invariant levels for several days (Hoagland and Arnon 1938;Yamazaki 1982).…”

Response of Nitrogen Metabolism in Masson Pine Needles to Elevated CO2

“…Thornton [37] noted that plants had feedback regulation on the absorption and metabolism of NH 4 + , NO 2 − and NO 3 − ; therefore, an increase in the NO 3 − content may cause a decrease in the other two forms of nitrogen. Furthermore, Ma [38] noted that an increase in the amino acid content would also inhibit the absorption and metabolism of inorganic nitrogen by plants. In general, the content of amino acids increased with increasing stress time and reached a maximum value at 24 h, particularly for threonine, arginine and tryptophan (Table 2).…”