Root morphology and exudation define a plants’ sphere of influence in soils. In turn, soil characteristics influence plant growth, morphology, root microbiome, and rhizosphere chemistry. Collectively, all these parameters have significant implications on the major biogeochemical cycles, crop yield, and ecosystem health. However, how plants are shaped by the physiochemistry of soil particles is still not well understood. We explored how particle size and chemistry of growth substrates affect root morphology and exudation of a model grass. We grew Brachypodium distachyon in glass beads with various sizes (0.5, 1, 2, 3 mm), as well as in sand (0.005, 0.25, 4 mm) and in clay (4 mm) particles and in particle‐free hydroponic medium. Plant morphology, root weight, and shoot weight were measured. We found that particle size significantly influenced root fresh weight and root length, whereas root number and shoot weight remained constant. Next, plant exudation profiles were analyzed with mass spectrometry imaging and liquid chromatography–mass spectrometry. Mass spectrometry imaging suggested that both, root length and number shape root exudation. Exudate profiles were comparable for plants growing in glass beads or sand with various particles sizes, but distinct for plants growing in clay for in situ exudate collection. Clay particles were found to sorb 20% of compounds exuded by clay‐grown plants, and 70% of compounds from a defined exudate medium. The sorbed compounds belonged to a range of chemical classes, among them nucleosides, organic acids, sugars, and amino acids. Some of the sorbed compounds could be desorbed by a rhizobacterium (Pseudomonas fluorescens WCS415), supporting its growth. This study demonstrates the effect of different characteristics of particles on root morphology, plant exudation and availability of nutrients to microorganisms. These findings further support the critical importance of the physiochemical properties of soils when investigating plant morphology, plant chemistry, and plant–microbe interactions.

中文翻译：

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根茎形态和分泌物的可用性受短枝chy的粒径和化学性质的影响。

根的形态和渗出定义了植物在土壤中的影响范围。反过来，土壤特性会影响植物的生长，形态，根部微生物组和根际化学。总的来说，所有这些参数对主要的生物地球化学循环，作物产量和生态系统健康都有重要影响。但是，如何通过土壤颗粒的物理化学来塑造植物的方式仍不为人所知。我们探讨了生长基质的粒径和化学性质如何影响模型草的根系形态和渗出。我们种植了短枝Bra在各种尺寸（0.5、1、2、3 mm）的玻璃珠，沙子（0.005、0.25、4 mm）和粘土（4 mm）颗粒以及无颗粒水培介质中。测量植物形态，根重和苗重。我们发现，颗粒大小显着影响根鲜重和根长，而根数和苗重保持恒定。接下来，用质谱成像和液相色谱-质谱法分析植物的渗出特性。质谱成像表明，根的长度和根数均会影响根的渗出。对于在玻璃珠或沙中生长的各种粒径的植物而言，渗出物特征是可比的，但是对于在粘土中生长的植物而言，渗出物特征却是不同的。发现黏土颗粒吸收黏土植物分泌的20％的化合物，和70％的化合物来自特定的分泌液介质。吸附的化合物属于多种化学类别，其中包括核苷，有机酸，糖和氨基酸。某些吸附的化合物可能被根瘤菌解吸（荧光假单胞菌WCS415），支持其生长。这项研究证明了颗粒的不同特性对根系形态，植物渗出物和微生物养分利用率的影响。这些发现进一步支持了在研究植物形态，植物化学以及植物与微生物相互作用时土壤理化特性的至关重要性。