Elevated CO2 effects on nutrient competition between a C3 crop (Oryza sativa L.) and a C4 weed (Echinochloa crusgalli L.)

Abstract

Rice (a C 3 crop) and barnyard grass (Echinochloa crusgalli L.) (a C 4 weed) were grown in a 1:1 mixture in a paddy field in ambient condition and with supplemented free air carbon dioxide enrichment (FACE, CO 2 concentration ? 200 lmol mol -1 ), in order to evaluate the impact of rising atmospheric carbon dioxide on nutrient competition between rice crop and weed. Results showed that elevated CO 2 significantly enhanced the biomass, tillers, leaf area index (LAI) and net assimilation rate (NAR) of rice, but reduced those of barnyard grass after elongation. Tissue nitrogen (N) concentrations were decreased in both competitors, but their phosphorus (P) and potassium (K) concentration were increased. The increase in tissue P concentration of rice was greater than that in barnyard grass. Furthermore, the absolute uptake of C, N, P, K by rice were increased while those of barnyard grass decreased. As a result, significant increase of the ratios of rice/ barnyard grass of biomass and absolute nutrient uptake were observed under elevated CO 2 . The results suggest that rising atmospheric CO 2 concentration could alter the competition between rice and barnyard grass in paddy fields in favor of rice. The ability of rice to compete more successfully for nitrogen and phosphorous under elevated CO 2 is likely an important factor underlying this response. More generally, the results suggest that elevated CO 2 may have varying implications on nutrient dynamics between different elements of overall plant biomass and the soil nutrients pool.

Elevated CO2 and O3 Levels Influence the Uptake and Leaf Concentration of Mineral N, P, K in Phyllostachys edulis (Carrière) J.Houz. and Oligostachyum lubricum (wen) King f.

“…This is consistent with previous findings that elevated CO 2 promotes nutrient uptake in plants to satisfy the demands of plant growth [7,11,12]. In addition, it is likely that elevated CO 2 could have various implications on nutrient dynamics between bamboo requirement and supplement among different bamboo species, which have proved in other plants [63]. However, the mechanisms underlying the observed discrepancy in nutrient demand of P. edulis and O. lubricum under elevated CO 2 remain unclear and need further research.…”

Influence of Elevated Co₂ on Agricultural Systems: A Review

“…In one of these studies, rice was grown under FACE approach at 570 and 370 ppm of CO2 in two consecutive growing seasons. Rice plants growing under elevated [CO2] had increases in NUE of 7.5%, 15.1%, and 6% at 30, 60, and 120 days after transplanting (ZENG et al, 2010), which was attributed to a lower leaf nitrogen concentration. Wheat has shown similar results regarding lower leaf nitrogen and grain protein (HOGY et al, 2009;ERBS et al, 2010).…”

“…v.95, n.2, p. 140 -155, 2020 DOI: 10.37856/bja.v95i2.3977 complicated by the evolution of resistance to multiple herbicides (Heap, 2020), threating the sustainability of rice production worldwide. Results by Zeng et al (2010) showed that elevated…”

“…Zeng et al (2010) analyzed competitiveness traits of rice, a C3 crop, and the C4 weedbarnyardgrass (Echinochloa crusgalli L.), when plants were allowed to compete under either ambient or elevated [CO2]. Barnyardgrass and other species in the Echinochloa genus are considered the most troublesome weed species in rice systems.…”

Genotypic Differences for Water‐Use Efficiency and Weed Competitiveness in Dry Direct‐Seeded Rice

“…Sedges compete with the crop for nutrients because their root systems are fibrous and the uptake of nutrients is influenced by the available soil moisture. Similarly, besides competing for CO 2 and light, grass weeds pose serious competition for water and nutrients in the soil (Zeng et al, 2011). In addition, rice genotypes respond differentially when sown in an aerobic environment (Singh et al, 2012).…”