Data from: Relative performance of non-local cultivars and local, wild populations of switchgrass (Panicum virgatum) in competition experiments

The possibility of increased invasiveness in cultivated varieties of native perennial species is a question of interest in biofuel risk assessment. Competitive success is a key factor in the fitness and invasive potential of perennial plants, and thus the large-scale release of high-yielding biomass cultivars warrants empirical comparisons with local conspecifics in the presence of competitors. We evaluated the performance of non-local cultivars and local wild biotypes of the tallgrass species Panicum virgatum L. (switchgrass) in competition experiments during two growing seasons in Ohio and Iowa. At each location, we measured growth and reproductive traits (plant height, tiller number, flowering time, aboveground biomass, and seed production) of four non-locally sourced cultivars and two locally collected wild biotypes. Plants were grown in common garden experiments under three types of competition, referred to as none, moderate (with Schizachyrium scoparium), and high (with Bromus inermis). In both states, the two “lowland” cultivars grew taller, flowered later, and produced between 2x and 7.5x more biomass and between 3x and 34x more seeds per plant than local wild biotypes, while the other two cultivars were comparable to wild biotypes in these traits. Competition did not affect relative differences among biotypes, with the exception of shoot number, which was more similar among biotypes under high competition. Insights into functional differences between cultivars and wild biotypes are crucial for developing biomass crops while mitigating the potential for invasiveness. Here, two of the four cultivars generally performed better than wild biotypes, indicating that these biotypes may pose more of a risk in terms of their ability to establish vigorous feral populations in new regions outside of their area of origin. Our results support an ongoing assessment of switchgrass cultivars developed for large-scale planting for biofuels.

本土多年生物种栽培品种的入侵性提升潜力，是生物燃料风险评估领域的热点研究问题。竞争能力是多年生植物适合度与入侵潜力的关键决定因素，因此大规模推广高产生物质品种时，需在有竞争者存在的条件下，将其与本地同种个体（conspecifics）开展实证对比研究。本研究在俄亥俄州与艾奥瓦州开展了两个生长季的竞争实验，评估了高草草原物种柳枝稷（Panicum virgatum L.，switchgrass）的非本地栽培品种与本地野生生物型（wild biotypes）的生长表现。在每个试验地点，本研究测定了4个非本地来源栽培品种与2个本地采集野生生物型的生长及繁殖性状，包括株高、分蘖数、开花期、地上生物量与种子产量。所有供试植株均在同质园（common garden）实验中种植，并设置三种竞争处理：无竞争、中度竞争（与须芒草（Schizachyrium scoparium）混种）以及高度竞争（与无芒雀麦（Bromus inermis）混种）。在两个州的试验中，两个‘低地型’栽培品种的株高更高、开花更晚，单株地上生物量为本地野生生物型的2~7.5倍，单株种子产量为其3~34倍；而其余两个栽培品种的上述性状与本地野生生物型无显著差异。竞争处理并未改变各生物型间的相对性状差异，仅枝条数（shoot number）除外：在高度竞争处理下，各生物型的枝条数更为相近。解析栽培品种与野生生物型间的功能性状差异，对培育生物质作物同时降低其入侵风险具有重要意义。本研究中，4个栽培品种中有2个整体表现优于野生生物型，表明这类品种在原产地以外的新区域建立旺盛逸生种群（feral populations）的能力可能带来更高的入侵风险。本研究结果支持针对用于生物燃料大规模种植的柳枝稷品种开展持续评估的必要性。