Divergent response of Chernozem organic matter towards short-term water stress in Poa pratensis L. rhizosphere and bulk soil in pot experiments: A spectroscopic study
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引用次数: 0
Abstract
Understanding and controlling rhizospheric processes under abiotic stress is one of the key challenges in addressing food security amid the climate crisis. In this work, the impact of short-term drought and overwatering on soil organic matter (SOM) of Haplic Chernozem in the rhizosphere of Poa pratensis L. and in bulk soil was investigated. The vegetation experiment was conducted in a climatic chamber at soil moisture levels of 35, 80, and 200 % of the field capacity. UV-Vis and spectrofluorometry were used to describe the water-extractable organic matter (WEOM) characteristics and fluorofores signature, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to describe functional group composition of SOM. Composition and properties of SOM and WEOM of Chernozem significantly change after exposure to short-term water stress. Drought does not affect the composition of rhizosphere SOM except increasing the proportion of polysaccharides, but leads to the decrease in aromaticity and increase in molecular weight of humic-like components of rhizosphere WEOM. These findings reflect Poa adaptation to water deficiency and microbial activity suppression which results in accumulation of SOM intermediate decomposition products. On the contrary, bulk WEOM wasn't affected by drought but SOM became enriched with aromatic and oxidised components. Overwatering leads to equalisation of bulk and rhizospheric SOM composition due to a decrease in the proportion of aromatic and carboxylic components of bulk SOM and the accumulation of microbial products in both bulk and rhizospheric SOM. In general, rhizospheric WEOM undergoes relatively significant changes relative to the optimum water regime under moisture deficit, and bulk WEOM — under overwatering. The findings illustrate the involvement of the both WEOM and SOM in maintaining resilience of the soil-plant system as well as the difference in watering conditions impact on SOM in rhizosphere and bulk soil. SOM spectral data can be used for assessing the state of soil systems, such as changes in microbial activity and adaptation of the soil-plant system to abiotic stress. Our findings also illustrate the differences in the organic matter transformation of the Poa pratensis rhizosphere and the bulk Chernozem depending on environmental factors.
在盆栽实验中,Chernozem 有机物对 Poa pratensis L. 根瘤菌圈和块状土壤中短期水分胁迫的不同反应:光谱研究
了解和控制非生物胁迫下的根瘤过程是应对气候危机中粮食安全问题的关键挑战之一。在这项工作中,研究了短期干旱和过度浇水对 Poa pratensis L.根圈和大块土壤中 Haplic Chernozem 土壤有机质(SOM)的影响。植被实验在气候箱中进行,土壤湿度分别为田间容量的 35%、80% 和 200%。紫外-可见光谱法和荧光光谱法用于描述水提取有机物(WEOM)的特征和荧光特征,漫反射红外傅里叶变换光谱法(DRIFTS)用于描述 SOM 的官能团组成。切尔诺泽姆的 SOM 和 WEOM 的组成和特性在受到短期水胁迫后发生了显著变化。干旱除了增加多糖的比例外,不会影响根瘤菌 SOM 的组成,但会导致根瘤菌 WEOM 的芳香度降低,腐殖质类成分的分子量增加。这些发现反映了 Poa 对缺水的适应性和微生物活动的抑制,从而导致 SOM 中间分解产物的积累。相反,WEOM 主体不受干旱影响,但 SOM 中的芳香和氧化成分却变得丰富起来。浇水过多会导致大体积 SOM 和根瘤层 SOM 成分的平衡,这是因为大体积 SOM 中芳香和羧基成分的比例下降,大体积 SOM 和根瘤层 SOM 中的微生物产物积累。一般来说,在缺水的情况下,根瘤WEOM相对于最佳水分状态会发生相对显著的变化,而在浇水过多的情况下,根瘤WEOM会发生相对显著的变化。研究结果表明,WEOM 和 SOM 都参与维持土壤-植物系统的恢复能力,以及浇水条件的不同对根瘤菌圈和块状土壤中 SOM 的影响。SOM 光谱数据可用于评估土壤系统的状态,如微生物活动的变化和土壤-植物系统对非生物胁迫的适应性。我们的研究结果还说明了 Poa pratensis 根圈和 Chernozem 主体土壤的有机质转化因环境因素而存在差异。
期刊介绍:
Soil & Tillage Research examines the physical, chemical and biological changes in the soil caused by tillage and field traffic. Manuscripts will be considered on aspects of soil science, physics, technology, mechanization and applied engineering for a sustainable balance among productivity, environmental quality and profitability. The following are examples of suitable topics within the scope of the journal of Soil and Tillage Research:
The agricultural and biosystems engineering associated with tillage (including no-tillage, reduced-tillage and direct drilling), irrigation and drainage, crops and crop rotations, fertilization, rehabilitation of mine spoils and processes used to modify soils. Soil change effects on establishment and yield of crops, growth of plants and roots, structure and erosion of soil, cycling of carbon and nutrients, greenhouse gas emissions, leaching, runoff and other processes that affect environmental quality. Characterization or modeling of tillage and field traffic responses, soil, climate, or topographic effects, soil deformation processes, tillage tools, traction devices, energy requirements, economics, surface and subsurface water quality effects, tillage effects on weed, pest and disease control, and their interactions.