Mondal Surajit, Chakraborty Debashis
Division of Agricultural Physics, ICAR Indian Agricultural Research Institute, New Delhi, 110 012, India.
Heliyon. 2023 Aug 2;9(8):e18834. doi: 10.1016/j.heliyon.2023.e18834. eCollection 2023 Aug.
The process of soil compaction can cause various stresses on roots, ultimately limiting their growth and development within the soil. Understanding this phenomenon in real-world conditions can be challenging since the growth of roots is influenced by the soil environment. To investigate this issue, four experiments were conducted to examine the impact of topsoil (two in pots: with clay loam and sandy loam soils under two soil water regimes) and subsoil (in rhizobox: one with clay loam soil and the other with sandy loam soil, containing artificial vertical macropores) compaction on the relationship between edaphic factors and the physiological response of wheat roots. The topsoil compaction reduced root length, volume, and weight by 30-50% and the root diameter by ∼15% compared to the non-compact soil. The effect was reduced in the soil with higher clay content (clay loam), especially under the limited soil water condition. Plant physiological responses were adversely affected by compaction with a reduction in plant height. The transpiration rate was highly impacted (21-47% reduction) with the build-up of intercellular CO content in leaves (13-31%), especially with limited water applications. Root growth was severely restricted (>60%) in the compact subsoil layer, although the surface area and volume of roots increased in the overlying non-compact layer. Naturally occurring or artificial vertical macropores acted as escape channels, facilitating the roots to pass through the compact subsoil and grow abundantly in the loose soil below. However, plants in field conditions encounter a mix of loose and compact soil zones. By studying how roots respond to this soil heterogeneity, we can develop strategies to reduce the negative effects of soil compaction.
土壤压实过程会对根系造成各种应力，最终限制其在土壤中的生长和发育。由于根系生长受土壤环境影响，在实际条件下理解这一现象具有挑战性。为研究此问题，进行了四项实验，以考察表土（两项在花盆中进行：在两种土壤水分状况下，分别使用黏壤土和砂壤土）和底土（在根箱中进行：一项使用黏壤土，另一项使用砂壤土，含有人工垂直大孔隙）压实对土壤因子与小麦根系生理反应之间关系的影响。与未压实土壤相比，表土压实使根长、根体积和根重量减少30% - 50%，根直径减少约15%。在黏土含量较高的土壤（黏壤土）中，这种影响有所减轻，尤其是在土壤水分有限的条件下。压实对植物生理反应产生不利影响，导致株高降低。蒸腾速率受到很大影响（降低21% - 47%），同时叶片细胞间CO含量增加（13% - 31%），特别是在水分供应有限的情况下。在压实的底土层中，根系生长受到严重限制（>60%），尽管在上覆的未压实层中根表面积和根体积有所增加。天然存在的或人工的垂直大孔隙起到了逃逸通道的作用，便于根系穿过压实的底土并在下方疏松土壤中大量生长。然而，田间条件下的植物会遇到疏松和压实土壤区域的混合情况。通过研究根系如何应对这种土壤异质性，我们可以制定策略来减少土壤压实的负面影响。
