Surface tension and viscosity of axenic maize and lupin root mucilages
Surface tension and viscosity of axenic maize and lupin root mucilages
复制标题
DOI：
10.1046/j.1469-8137.1997.00859.x
复制
发表时间：
1997-12-01
期刊：
影响因子：
9.4
通讯作者：
Gregory, PJ
中科院分区：
文献类型：
--
作者：
Read, DB;Gregory, PJ
在许多植物中，粘液渗透到根与土壤之间的界面，但人们对其物理性质或对根际物理性质的影响知之甚少。粘液是从3-4天龄的轴生玉米(Zea Mays L.cv.)Freya)和羽扇豆属(Lupinus angustifolius L.cv.)梅里特)苗木。测定了一定水化范围内的表面张力和粘度，并用气相色谱分析了水解液中的中性糖。在总溶质浓度为0.7mgml(-1)时，玉米和羽扇豆胶的表面张力均降至48mN·m(-1)，表明存在强大的表面活性剂。胶乳粘度随溶质浓度的增加和温度的降低而增加。在总溶质浓度为0.7mgml(-1)时，玉米胶浆在20℃时的粘度为2.1mPa.S(约.是纯水的两倍)，在5℃时增加到3.3兆帕S。玉米和羽扇豆胶都表现出粘弹性行为。玉米粘液的主要成分是葡萄糖，而羽扇豆胶的主要成分是岩藻糖。表面张力和粘度的结果支持这样的观点，即在干燥的土壤中，粘液在维持根-土接触方面起着主要作用。随着表面张力的降低，粘液对周围土壤颗粒的润湿能力变得更强。此外，随着粘度和弹性的增加，与粘液接触的任何土壤颗粒的运动阻力也增加，实现了一定程度的根际结构稳定，并保持了水力连续性。目前尚不清楚这种表面活性物质是由根部主动分泌的，还是仅仅是根细胞渗漏的结果。
In many plants, mucilage permeates the interface between root and soil, yet little is known about its physical properties or its influence on the physical properties of the rhizosphere. Mucilage was collected from 3-4-d-old, axenically-grown maize (Zea mays L. cv. Freya) and lupin (Lupinus angustifolius L. cv. Merrit) seedlings. Surface tension and viscosity were measured over a range of mucilage hydration, and neutral sugar analyses of the hydrolysed mucilages were obtained by gas chromatography. Surface tension of both maize and lupin mucilage was reduced to similar to 48 mN m(-1) at total solute concentrations > 0.7 mg ml(-1), indicating the presence of powerful surfactants. Mucilage viscosity increased with increasing solute concentration and decreasing temperature. At a total solute concentration of 0.7 mg ml(-1), the viscosity of maize mucilage at 20 degrees C was 2.1 mPa s (approx. double that of pure water), increasing to 3.3 mPa s at 5 degrees C. Both maize and lupin mucilage showed viscoelastic behaviour. The major component of maize mucilage was found to be glucose, but in lupin it was fucose.The surface tension and viscosity results support the idea that mucilage plays a major role in the maintenance of root-soil contact in drying soils. As surface tension decreases, the ability of the mucilage to wet the surrounding soil particles becomes greater. Also, as viscosity and elasticity increase, the resistance to movement of any soil particles in contact with the mucilage increases, a degree of stabilization of the rhizosphere structure is achieved and hydraulic continuity is maintained. It is unclear whether the surfactant is actively secreted by the root or is present simply as a result of leakage from root cells.