Different ways in which CO2 can be released during the turnover of roots in soil
Different ways in which CO2 can be released during the turnover of roots in soil
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DOI：
10.1007/s00374-017-1193-1
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发表时间：
2017-03
影响因子：
6.5
通讯作者：
Venkata S. S. R. Marella-Venkata-S.-S.-R.-Marella-49626495;P. Roberts;P. Hill;Davey L. Jones
中科院分区：
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作者：
Venkata S. S. R. Marella-Venkata-S.-S.-R.-Marella-49626495;P. Roberts;P. Hill;Davey L. Jones
在这里，我们调查了根龄和死亡模式如何影响其随后的营业额和土壤中的C损失率。年轻的白色和老色素的根ofCistus monspeliensis切除（模拟死亡的机械切断）或冷冻（模拟死亡的细胞破裂），并立即埋在土壤中。然后测量土壤中CO2随时间的流失。在一个平行的实验中，在没有土壤的情况下，从切断或破裂的根CO2损失率进行了测定。我们的研究结果显示，根化学与年龄的巨大差异，与年轻的根具有较低的C：N比和更高的营养含量（可溶性C，N，P和K）。根系年龄和死亡模式导致非常不同的时间模式的C释放从土壤中。从土壤中损失的碳量为：断根白色根（42.6 ± 3.3 mg C）>断根色素根（27.7 ± 0.4 mg C）=断根白色根（27.1 ± 0.5 mg C）>断根色素根（10.1 ± 1.0 mg C）>土壤（3.0 ± 0.2 mg C）。因此，根据治疗，7至41%的总根源C损失的CO2在实验的持续时间。与无土处理的比较表明，埋在土壤中的断根的CO2释放与微生物的分解无关，而是由根诱导的自噬引起的，以保持自身的代谢活性。断裂的根也引起了快速损失的CO2，我们归因于根溶质到土壤中的扩散损失和随后的微生物矿化。令人惊讶的是，从土壤中的C损失率是从切断的根尖比那些破裂。我们的研究结果意味着两种不同的碳损失途径取决于根的死亡方式，一种绕过微生物群落，另一种流过它。
Here, we investigated how root age and mode of death influenced their subsequent turnover and rate of C loss from soil. Young white-coloured and older pigmented roots ofCistus monspeliensiswere excised (to simulate death by mechanical severance) or frozen (to simulate death by cell rupture) and immediately buried in soil. CO2loss from soil was then measured over time. In a parallel experiment, the rate of CO2loss from severed or ruptured roots in the absence of soil was determined. Our results revealed large differences in root chemistry related to age, with young roots having a lower C:N ratio and a greater nutrient content (soluble C, N, P and K). Both root age and mode of death resulted in very different temporal patterns of C release from soil. The amount of C lost from soil followed the series: severed white roots (42.6 ± 3.3 mg C) > ruptured pigmented roots (27.7 ± 0.4 mg C) = ruptured white roots (27.1 ± 0.5 mg C) > severed pigmented roots (10.1 ± 1.0 mg C) > soil only (3.0 ± 0.2 mg C). Therefore, depending on the treatment, 7 to 41% of the total root-derived C was lost as CO2over the duration of the experiment. Comparison with soil-free treatments revealed that the CO2release from the severed roots buried in soil was not associated with microbial breakdown but caused by root-induced autophagy in an attempt to keep themselves metabolically active. Ruptured roots also induced a rapid loss of CO2which we ascribe to the diffusive loss of root solutes into the soil and subsequent microbial mineralization. Surprisingly, the rate of C loss from soil was greater from the severed root tips than those that were ruptured. Our results imply two distinct routes of C loss dependent on how roots die, one which bypasses the microbial community and one which flows through it.