SGER: Using Stable Isotopes as Tracers to Measure Below Ground Neighborhoods in Plant Populations

SGER：使用稳定同位素作为示踪剂来测量植物种群的地下邻域

• 批准号: 9708165
• 负责人: Brenda Casper
• 金额: --
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-03-15 至 1999-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9708165&HistoricalAwards=false
• 关键词: SGER; Using; Stable; Isotopes; Tracers

9708165 Casper The ultimate goals of this project are to measure the lateral spread of plant roots and to determine how rooting area changes with certain soil conditions and the presence of neighboring plants. The one year project funded here will primarily test whether recently devised techniques in plant science can be applied to this problem. We will test to what extent isotopes of cesium, lithium, rubidium, and strontium can be used as tracers to determine whether plants take up nutrients from a particular point in soil space. These elements serve as nutrient analogs which means that plants should take them up in place of common nutrients. Because they are rare within most soils, we can place solutions containing these elements at defined locations in the soil and by detecting their presence in newly produced plant tissue, be certain that the plant's root system intersects the pocket of tracer. By knowing how many of the plants in the population have taken up a particular tracer, we can determine exactly how many root systems overlap in the area marked by tracer. The use of all four tracers within a single population will enable us to measure root extension in four different directions and facilitate estimates of lateral rooting area. A second technique will be applied to the question of whether fungal-root associations mycorrhizae) enlarge the soil area over which a plant takes up nutrients. GORE-TEXR fabric will be used to separate tracer from plant roots. Roots and nutrients do not pass through the small pores in the fabric but mycorrhizal hyphae do. By physically isolating roots from tracers in this way, we can determine whether the mycorrhizae extend the distance over which a plant takes up nutrients. Another experiment will determine whether the tracer moves laterally in the soil even in the absence of plant roots. These experiments are important to understanding how below ground competition for soil resources takes place among plants. We can measure how the presenc e of below ground competition affects plant growth, but we have little knowledge of which individuals are engaged in the competition. We do not know whether interactions primarily occur between nearest neighbors or whether root systems extend beyond nearest neighbors to include many other plants. It is impossible to determine this information from excavating root systems because the fine roots that are most active in nutrient uptake cannot be recovered from the soil. This information is essential to determining how the number and proximity of neighboring plants affect plant growth, whether it be in agricultural or natural systems.

小行星9708165 该项目的最终目标是测量植物根系的横向扩展，并确定生根面积如何随特定土壤条件和相邻植物的存在而变化。 这里资助的为期一年的项目将主要测试最近设计的植物科学技术是否可以应用于这个问题。 我们将测试铯、锂、铷和锶的同位素在多大程度上可以用作示踪剂，以确定植物是否从土壤空间的特定点吸收养分。 这些元素作为营养素类似物，这意味着植物应该吸收它们来代替常见的营养素。 由于它们在大多数土壤中很少见，我们可以将含有这些元素的溶液放置在土壤中的指定位置，并通过检测它们在新产生的植物组织中的存在，确保植物的根系与示踪剂的口袋相交。 通过知道种群中有多少植物 当我们用了一种特定的示踪剂时，我们可以准确地确定在示踪剂标记的区域内有多少根系重叠。 在一个单一的人口中使用所有四个示踪剂将使我们能够测量根在四个不同的方向延伸，并促进侧生根面积的估计。 第二项技术将被应用于真菌-根联合体是否扩大了植物吸收养分的土壤面积的问题。 GORE-TEXR织物将用于从植物根部分离示踪剂。 根和营养物质不通过织物上的小孔，但菌根菌丝可以。 通过这种方式将根与示踪剂物理隔离，我们可以确定真菌是否延伸了植物吸收养分的距离。 另一个实验将确定示踪剂是否在土壤中横向移动，即使在没有植物根的情况下。 这些实验对于理解植物之间如何在地下竞争土壤资源很重要。 我们可以测量地下竞争的存在如何影响植物生长，但我们对哪些个体参与竞争知之甚少。 我们不知道相互作用是否主要发生在最近的 或者根系是否延伸到最近的邻居之外，包括许多其他植物。 通过挖掘根系来确定这一信息是不可能的，因为在养分吸收方面最活跃的细根不能从土壤中恢复。 这些信息对于确定邻近植物的数量和接近程度如何影响植物生长至关重要，无论是在农业系统还是自然系统中。