Changes in plant C, N and P ratios under elevated [CO2] and canopy warming in a rice-winter wheat rotation system

Jianqing Wang,Xiaoyu Liu,Genxing Pan,Xuhui Zhang,Shu Kee Lam,Lianqing Li

doi:10.1038/s41598-019-41944-1

Abstract

Elevated atmospheric CO2 concentration ([CO2]) can stimulate plant growth through enhanced photosynthetic rate. However, plant C, N and P ratios in response to elevated [CO2] combined with canopy warming in rice-winter wheat rotation system remain largely unknown. Here we investigated the impacts of elevated [CO2] and warming on plant nutrient ratios under open-air conditions. Four treatments including the ambient condition (CK), elevated [CO2] (500 ppm, CE), canopy warming (+2 °C, WA), and the combination of elevated [CO2] and warming (CW) were used to investigate the responses of plant C, N and P ratios in a rice-winter wheat rotation system in southeast China. Results showed that elevated [CO2] increased C:N ratio in whole plant by 8.4–14.3% for both crops, and increased C:P ratio by 11.3% for rice. The changes in ratio were due to an increase in C concentration by 0.8–1.2% and a reduction in N concentration by 7.4–10.7% for both crops, and a reduction in P concentration by 10.0% for rice. Warming increased N allocation in rice leaf and N concentration by 12.4% for rice, resulting in increases in the ratios of N to C and P by 11.9% and 9.7% in rice, but not in wheat. However, CW had no effect on plant C:N ratio in rice, indicating the positive effect of elevated [CO2] could offset the negative impact of warming on C:N ratio. By contrast, CW significantly decreased plant C:P and N:P ratios by 16% due to the increase in P allocation in stem for wheat. These results suggest that impacts of climate change on plant nutrient balance occur through interactions between the effects of climate change on nutrient uptake and allocation, which is important for food quality and productivity under global climate change.

Highlights

Global atmospheric carbon dioxide concentration ([CO2]) has increased rapidly due to the ongoing anthropogenic activities since the industrial revolution[1]
The main objective of this study was to examine the changes in plant nutrient (C, N and P) uptake and their ratios in different plant functional organs in a summer rice-winter wheat rotation system under simulated climate change conditions
Our study demonstrated that the combination of elevated [CO2] and warming had no effect on C or N concentration, but remarkably increased P concentration in wheat (Fig. 1)

Summary

Introduction

Global atmospheric carbon dioxide concentration ([CO2]) has increased rapidly due to the ongoing anthropogenic activities since the industrial revolution[1]. Previous studies suggested that future plants would be exposed to a global nutrient imbalance under elevated [CO2]8–11, with lower N concentration[10] or increased C:N and C:P ratios in plant functional organs[9]. Cheng et al found that elevated night (from 20:00 until 04:00) temperature by ca 10 °C had no effect on whole rice plant C or N concentration, but increased N concentration in the living leaf and reduced its allocation to the ear[13]. Results from these studies were mainly dependent on plant types and experimental conditions. We aim to provide knowledge for improving food quality and nutrient management in agriculture under future climate change

Objectives

Methods

Results

Discussion

Conclusion