近日，华中农业大学资源与环境学院植物营养生物学课题组联合中国农业大学在油菜适应紧实土壤胁迫适应性机制研究中取得新进展，相关成果以“Compacted soil adaptability of Brassica napus driven by root mechanical traits”为题发表在Soil & Tillage Research上。
由机械化耕作、土壤干旱、长期免耕和农业集约化生产等造成的土壤压实会严重破坏土壤结构，同时显著阻碍作物生长和产量提高，但目前学术界对土壤压实如何影响植物功能和生态策略仍不清楚。基于此背景，课题组以我国重要油料作物—甘蓝型油菜为研究对象，探究具有不同机械特征的油菜品种如何影响土壤紧实胁迫适应性、根系性状之间的权衡和养分获取能力，以及不同油菜品种的基因型响应特征。
结果表明，土壤压实显著抑制了根系下扎深度和根系生长，降低养分吸收和植物生物量累积。然而，土壤压实显著促进甘蓝型油菜根系平均直径和根冠比增加。在紧实土壤中，具有较强根系力学性质（根系拉力、抗拉强度和弹性模量）的甘蓝型油菜品种根系具有较高浓度的纤维素和木质素，且具有显著较大的根系下扎深度和比根长，同时根系分泌显著较多的有机酸和多糖类物质。土壤压实导致土壤中具有较多的小孔隙，根-土界面分布较多的细根促进根系下扎，同时诱导产生较多根系分泌物（有机酸和糖类物质）在根系下扎中起润滑作用，促进根系形态的建立和生物量累积。因此，较强根系力学性质的甘蓝型油菜品种中更多的细根和根系分泌较多的有机酸和糖类物质，对甘蓝型油菜根系在压实土壤中的下扎至关重要。
我校博士研究生段贤杰为论文第一作者，石磊教授和中国农业大学金可默副教授为共同通讯作者。我校博士生刘玲、何阳波副教授、徐芳森教授，法国农学院毛准研究员、中国农科院西双版纳热带植物园夏尚文副研究员、英国雷丁大学John P. Hammond教授和英国詹姆斯？赫顿研究所Philip J. White教授也参与了该项研究。该研究得到了国家自然科学基金和苏格兰政府战略研究计划等项目的支持。
【英文摘要】
Soil compaction due to mechanized farming operations is a recurrent issue affecting crop growth and yield. Yet, how soil compaction affects plant functions and ecological strategies is poorly known. With Brassica napus, i.e. a widespread crop species as study object, we aim to understand （i） how soil compaction impacts root and shoot traits related to the plant's well-being, nutrient acquisition of Brassica napus with different mechanical robustness, as well as their trade-offs, and （ii） how such impacts vary among different cultivars. To do this, we cultivated six cultivars of Brassica napus in non-compacted （control） and compacted （treatment） soils, respectively, in a sand culture system. After harvesting, a series of mechanical, morphological and chemical traits of roots and/or shoots were measured. Results showed that soil compaction significantly limited root penetration depth and root system establishment in morphological traits, leading further to significant reduction in nutrients acquisition and plant biomass accumulation. However, soil compaction significantly increases the average root diameter and root/shoot ratio, and facilitate more root exudates secretion （e.g. organic acids and polysaccharides） of Brassica napus cultivars. The Brassica napus cultivars with large root mechanical traits （e.g. root tensile force, root tensile strength and modulus of elasticity） had higher root cellulose and lignin concentrations and showed a stronger response in maximum root depth and specific root length compared with Brassica napuscultivars with small root mechanical traits in compacted treatment, which resulted in the greater fine root length and more root exudates secretion at root-soil interface. Furthermore, deep rooting enhanced nutrients acquisition and further biomass accumulation in compacted soil. Totally, the Brassica napus cultivars with large root mechanical traits with more fine roots and root exudates were critical for Brassica napusroot penetration into a deep soil layer in compacted soil.
论文链接：https://doi.org/10.1016/j.still.2023.105785
