Growth Strategy of Rhizomatous and Non-Rhizomatous Tall Fescue Populations in Response to Defoliation

Abstract

Abstract:The aim of this study was to determine the morphology of rhizome production, in two contrasting rhizomatous (R) and non-rhizomatous (NR) tall fescue (Schedonorus arundinaceus (Schreb.) Dumort) populations, and to assess whether rhizome production is associated with changed biomass allocation or plant growth pattern. Growth of R and NR populations was compared, under hard defoliation (H, 50 mm stubble), lax defoliation (L, 100 mm stubble), or without defoliation (U, uncut). Populations were cloned and grown in a glasshouse and defoliated every three weeks, with destructive harvests performed at 6, 12 and 18 weeks. R plants allocated more biomass to root and less to pseudostem than NR plants. Plant tiller numbers were greatly reduced by defoliation, and R and NR populations differed in leaf formation strategy. R plants had narrower leaves than NR, but their leaves were longer, because of greater leaf elongation duration. R plants were more plastic than NR plants in response to defoliation. Ultimately, biomass allocation to rhizomes did not differ between populations but R plants exhibited a subtle shift in distribution of internode length with a few longer internode segments typically located on secondary and tertiary tillers.

Drought weakens the positive effects of defoliation on native rhizomatous grasses but enhances the drought‐tolerance traits of native caespitose grasses

“…Present studies showed that the slower tiller regrowth of Hesperostipa species may be better adapted to drought, and the tiller growth rates responded positively to defoliation (Broadbent, Bork, & Willms, ). However, the effects of drought and defoliation on tiller growth rate of rhizomatous grasses are site specific and varied (Bryant, Matthew, & Hodgson, ; N'Guessan, ). Nevertheless, these works lack quantitative analysis to explore the tipping point of drought tolerance of the caespitose and rhizomatous grasses when coping with water stress, which inhibits the assessments of how drought affects these native plant species.…”

Forage Plant Ecophysiology: A Discipline Come of Age

“…Dumort (tall fescue) [20]. Surprisingly, biomass allocation to rhizomes did not differ statistically between the rhizomatous and non-rhizomatous populations studied (although it was markedly reduced by defoliation in both populations).…”

“…Rhizomatous tall fescue plants had a longer interval between the appearance of successive leaves, an increased rate of tiller bud site filling to compensate for the reduced number of bud sites, and longer, narrower leaves than the non-rhizomatous population. However, this is felt to reflect the adaptation to infrequent and frequent defoliation, respectively, in the two populations, and is not thought to be a direct consequence of rhizomatous or non-rhizomatous growth habits [20]. The rhizomatous population displayed increased biomass allocation to root and decreased biomass allocation to pseudostem compared to the non-rhizomatous population, but the functional significance of this is not clear [20].…”

Effect of Simulated Grazing on Morphological Plasticity and Resource Allocation of Aeluropus lagopoides

“…Ungrazed tillers of Leymus chinensis exhibited phenotypic plasticity in response to the defoliation of neighboring shoots in grasses with the clonal reproduction system [24]. However, Bryant et al [25] found that rhizomatous populations of Schedonorus arundinaceus were more plastic in response to defoliation than non-rhizomatous ones. During grazing, large herbivores directly decrease plant height and trigger grazing intensity-dependent plastic responses [26].…”