Silicon Effects on Biomass Carbon and Phytolith-Occluded Carbon in Grasslands Under High-Salinity Conditions

Abstract

Changes in climate and land use are causing grasslands to suffer increasingly from abiotic stresses, including soil salinization. Silicon (Si) amendment has been frequently proposed to improve plant resistance to multiple biotic and abiotic stresses and increase ecosystem productivity while controlling the biogeochemical carbon (C) cycle. However, the effects of Si on plant C distribution and accumulation in salt-suffering grasslands are still unclear. In this study, we investigated how salt ions affected major elemental composition in plants and whether Si enhanced biomass C accumulation in grassland species in situ. In samples from the margins of salt lakes, our results showed that the differing distance away from the shore resulted in distinctive phytocoenosis, including halophytes and moderately salt-tolerant grasses, which are closely related to changing soil properties. Different salinity (Na + /K + , ranging from 0.02 to 11.8) in plants caused negative effects on plant C content that decreased from 53.9 to 29.2% with the increase in salinity. Plant Si storage [0.02-2.29 g Si m −2 dry weight (dw)] and plant Si content (0.53 to 2.58%) were positively correlated with bioavailable Si in soils (ranging from 94.4 to 192 mg kg −1). Although C contents in plants and phytoliths were negatively correlated with plant Si content, biomass C accumulation (1.90-83.5 g C m −2 dw) increased due to the increase of Si storage in plants. Plant phytolith-occluded carbon (PhytOC) increased from 0.07 to 0.28 of dry mass with the increase of Si content in moderately salt-tolerant grasses. This study demonstrates the potential of Si in mediating plant salinity and C assimilation, providing a reference for potential manipulation of long-term C sequestration via PhytOC production and biomass C accumulation in Si-accumulator dominated grasslands.

Changes in Plant and Grain Quality of Winter Oat (Avena sativa L.) Varieties in Response to Silicon and Sulphur Foliar Fertilisation under Abiotic Stress Conditions

“…Silicon accumulation is known to decrease the carbon content of the aboveground tissues of plants, especially grasses like rice. Liu et al [ 27 ] reported that, in their research, the C content of plants was negatively correlated with the Si content of plants, but carbon accumulation increased due to more Si being stored. Their results also suggest that Si plays an important role in regulating plant C accumulation and long-term C storage in salt-tolerant Si accumulators.…”

“…Digestion lasted for 2 h, then the samples were allowed to cool. We used a specific (Jones) conversion factor for the conversion of nitrogen content to protein content, which, in the case of oats, is 5.83 [ 27 , 52 ].…”

Accumulation and partitioning of toxic trace metal(loid)s in phytoliths of wheat grown in a multi-element contaminated soil

“…The second aliquots of the above-ground plant samples were cut into 2-mm pieces for phytolith extraction according to a wet oxidation method modified after that described by Liu et al (2020a), to obtain high amount of phytoliths by adding increased number of individual plants in the aliquot. Briefly, 2.5 g of dried plant fragments were digested in a 50 mL glass digestion tank with 25 mL concentrated HNO3 and 5 mL 30% H2O2.…”

“…Furthermore, a strongly negative correlation between plant C content and phytoliths in wheat leaves under HPs suggests a defense trade-off strategy of Si substitution for C-based structural compounds in plant tissues under severe contamination scenario (Neu et al, 2017). It was suggested that high Si accumulation in plant tissues could readily biosynthesize structural components in plant cell walls with low energy cost than C-based compounds (i.e., lignin or phenolics), which might increase TTM sequestration in phytoliths (Ma et al, 2015) and lead to high biomass C accumulation, especially for Si-accumulator plants under environmental stresses (Schaller et al, 2012;Liu et al, 2020a).…”

Phytolith‐occluded carbon in leaves of Dendrocalamus Ronganensis influenced by drought during growing season

“…Given that the increase in atmospheric carbon dioxide (CO 2 ) concentration strongly contributes to the dangerous effects of climate change (IPCC, 2007) much research has sought to identify practical methods to reduce atmospheric CO 2 concentration(Guo et al, 2015; Li, Song, Parr, & Wang, 2013; Parr et al, 2010; Song et al, 2011; Song et al, 2016). Recent research indicates that phytolith‐occluded carbon (PhytOC) in plants, soils, and sediments may be an important sink for CO 2 sequestered from the atmosphere (Liu, Song, et al, 2020; Parr et al, 2009; Parr et al, 2010; Parr & Sullivan, 2011; Zuo & Lu, 2011).…”