Abstract

Carbon (C) occluded in phytoliths is stable and an important source of long-term C storage into the agroecosystems. As a silicon (Si) accumulator crop, rice produces a large amount of phytolith occluded carbon (PhytOC) and which plays a crucial role in the coupled biogeochemical cycle of C and Si. In this study, we sampled above ground biomass from 22 intensively cultivated rice ecosystems to evaluate the rate of C sequestration through phytoliths. Depending on the rice varieties there exist a great variability in PhytOC content (0.12–0.26%) across the rice ecosystems. The collected samples were further classified into three groups: viz., long (>140 days), medium (125–140 days) and short duration (<125 days). The above-ground net primary productivity (ANPP) varied from 5174 to 13,394 kg ha⁻¹ and recorded significantly (p < 0.05) higher in the relatively long duration variety compared to medium and short duration variety. The collected rice varieties showed a strong positive correlation (p < 0.05, R² = 0.45) between ANPP and crop duration. With the increase in varietal duration, phytolith content was non-significant (p > 0.05) whereas, the PhytOC content found to be significant (p < 0.05). The long-duration (>140 days) varieties showed 69.7% and 164.0% higher PhytOC sequestration flux over medium and short-duration varieties, respectively. Our results suggest that the Indian rice ecosystems sequester 0.95 Tg CO₂ yr⁻¹ through Phytoliths, which is equivalent to the 15.5% of PhytOC sink in the global rice field. Considering the PhytOC flux of relatively higher PhytOC accumulating long duration varieties, the annual PhytOC sink rate in the Indian rice ecosystems can be increased to ∼4 folds over the current rate. It was revealed that the selection of higher PhytOC accumulating long duration varieties can enhance the phytolith C sequestration.

摘要

植硅体中的碳 (C) 是稳定的，是将碳长期储存到农业生态系统中的重要来源。水稻作为一种硅（Si）蓄积作物，会产生大量的植硅体吸留碳（PhytOC），在C和Si的耦合生物地球化学循环中起着至关重要的作用。在这项研究中，我们从 22 个集约栽培的水稻生态系统中采样了地上生物量，以评估通过植硅体固碳的速率。根据水稻品种的不同，水稻生态系统中的 PhytOC 含量（0.12-0.26%）存在很大差异。收集的样本进一步分为三组：即长（> 140 天）、中（125-140 天）和短持续时间（<125 天）。地上净初级生产力（ANPP）从 5174 到 13,394 kg ha ^-1并 在相对长的品种中记录显着（p < 0.05）高于中短品种。收集的水稻品种在 ANPP 和作物持续时间之间显示出很强的正相关（p  < 0.05，R ² = 0.45）。随着品种持续时间的增加，植硅体含量不显着（p  > 0.05），而 PhytOC 含量显着（p  < 0.05）。长期限（>140 天）品种的 PhytOC 封存通量分别比中期限和短期限品种高 69.7% 和 164.0%。我们的结果表明，印度水稻生态系统在₂年^-1年间隔离了 0.95 Tg CO通过植硅体，相当于全球稻田中 15.5% 的 PhytOC 汇。考虑到相对较高的 PhytOC 积累长期品种的 PhytOC 通量，印度水稻生态系统中的年 PhytOC 汇率可以增加到当前速率的 4 倍。结果表明，选择具有较高 PhytOC 积累的长持续时间品种可以增强植硅体 C 的封存。