Variation in the role of the flag-leaf in reproductive effort of semiarid rangeland bunchgrasses

IF 2.7 3区 环境科学与生态学 Q2 ECOLOGY
Ecosphere Pub Date : 2024-08-19 DOI:10.1002/ecs2.4870
Erik P. Hamerlynck, Kathleen M. Quigley, Rory C. O'Connor
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引用次数: 0

Abstract

Understanding the mechanisms underlying viable seed production of perennial bunchgrasses is critical to improving restoration and conservation success in Great Basin sagebrush steppe rangelands. We studied the effects of pre- and post-anthesis flag-leaf removal and post-anthesis seed-head shading on reproductive effort in two important rangeland restoration species, the exotic crested wheatgrass (Agropyron cristatum) and native squirreltail (Elymus elymoides). Flag-leaf removal had distinct, species-specific effects on seed filling. Pre-anthesis flag-leaf removal in crested wheatgrass reduced the proportion of filled seeds, while post-anthesis removal did not. In contrast, squirreltail increased filled seed proportions regardless of flag-leaf removal timing. Neither flag-leaf removal treatment affected seed quality, as quantified by seed-specific mass (in grams per square meter), which significantly reduced with seed-head shading in both species. Seed-head shading reduced total propagule production (unfilled + filled seeds) in crested wheatgrass but increased it in squirreltail, possibly due to our shading method protecting from seed-head herbivory or high-light stress. Flag-leaf removal in the squirreltail also induced a negative shading effect on filled seed area, mass, and specific mass. These findings suggest flag leaves can modulate reproductive effort outside of seed provisioning, either by maintaining pre-fertilized seed viability, as in crested wheatgrass, or acting as a competitive sink to the fully emerged seed-head, as in squirreltail. Moreover, this study demonstrates photosynthetic activity by the seed-head itself is critical to the expression of seed quality traits important to seedling establishment success of semiarid perennial bunchgrasses.

Abstract Image

旗叶在半干旱牧场丛生禾本科植物繁殖过程中的作用差异
了解多年生丛生禾本科植物有活力种子生产的基本机制对于提高大盆地鼠尾草干草原牧场的恢复和保护成功率至关重要。我们研究了花前和花后摘除旗叶以及花后遮挡种子头对两种重要牧场恢复物种繁殖努力的影响,这两种物种是外来的冠麦草(Agropyron cristatum)和本地的鼠尾草(Elymus elymoides)。移除旗叶对种子灌浆有不同的、物种特有的影响。在冠麦草花期前摘除旗叶会降低灌浆种子的比例,而在花期后摘除则不会。与此相反,松鼠尾草无论何时摘除旗叶都会增加灌浆种子的比例。去除旗叶的两种处理方法都不会影响种子质量,以种子质量(单位:克/平方米)来量化,这两种植物的种子质量都会随着种头遮光而显著降低。遮挡种头减少了凤尾麦冬的繁殖体总产量(未灌浆种子+灌浆种子),但却增加了松鼠尾的繁殖体总产量,这可能是由于我们的遮挡方法保护了种头免受食草动物或强光胁迫。在松鼠尾草中去除旗叶也会对填充种子的面积、质量和比质量产生负面的遮光效应。这些研究结果表明,旗叶可以调节种子供应之外的繁殖努力,要么像凤尾麦冬那样保持受精前种子的活力,要么像松鼠尾那样充当完全萌发的种子头的竞争汇。此外,这项研究还表明,种子头本身的光合作用对于种子质量特性的表达至关重要,而种子质量特性对于半干旱多年生丛生禾本科植物的育苗成功至关重要。
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来源期刊
Ecosphere
Ecosphere ECOLOGY-
CiteScore
4.70
自引率
3.70%
发文量
378
审稿时长
15 weeks
期刊介绍: The scope of Ecosphere is as broad as the science of ecology itself. The journal welcomes submissions from all sub-disciplines of ecological science, as well as interdisciplinary studies relating to ecology. The journal''s goal is to provide a rapid-publication, online-only, open-access alternative to ESA''s other journals, while maintaining the rigorous standards of peer review for which ESA publications are renowned.
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