Etiolated regrowth of three bromegrass (Bromus) species after defoliation at different developmental stages

Abstract

Smooth bromegrass (Bromus inermis Leyss.), meadow bromegrass (Bromus riparius Rehm.) and hybrid bromegrass (B. riparius × B. inermis) are widely used for hay and pasture in temperate regions of the world. Three bromegrass species have variable capacities to regrow following defoliation and remobilization of stored energy after defoliation may vary among these grasses. A field study was conducted in 2006 and 2007 in Saskatoon (52°07′N, 106°38′W), Canada to determine etiolated regrowth of three bromegrass species after defoliation to a 2.5‐cm stubble height at the vegetative, stem elongation, reproductive stages of development, and after plant dormancy in late fall. After 5 and 10 days following defoliation, etiolated regrowth of meadow and hybrid bromegrass was greater than smooth bromegrass at the vegetative stage, and was greatest in meadow bromegrass, intermediate in hybrid bromegrass, and least in smooth bromegrass at the stem elongation stage. By 30 days and thereafter, etiolated regrowth was similar among three bromegrass species when defoliated at any growth stage. Etiolated regrowth was similar among the three species when defoliated at the reproductive stage. Meadow and hybrid bromegrasses produced more etiolated regrowth than smooth bromegrass on dormant plants in a growth chamber. The percentage of total etiolated regrowth to total full light regrowth increased with advanced growth stage in all three bromegrasses, and this percentage was higher in smooth bromegrass than the other two bromegrasses at the stem elongation and reproductive stages. The results of this study suggest that, following defoliation, meadow and hybrid bromegrass can mobilize stored energy more rapidly for regrowth than smooth bromegrass in the early regrowth period, contrary to the greater dependence on stored reserves in smooth bromegrass at the later growth stages.

Physiological and Germination Responses of Muskmelon (Cucumis melo L.) Seeds to Varying Osmotic Potentials and Cardinal Temperatures via a Hydrothermal Time Model

“…The influence of temperature and water potential on seed germination may be described and quantified using the HTT model. , The germination rate index and germination energy were the highest at 30 °C (MPa) and the lowest at 35 °C. The results of this study were similar to the findings made by Biligetu and Coulman, Gul and Weber, and Bewley et al, who documented that agronomic parameters were significantly affected by ψ and temperature. The rate of seed imbibition decreases as Ψ becomes more negative (decreased ψ), and as a result, the rate of germination and the percentage of germination both diminish (and may even stop altogether) .…”

Changes in water‐soluble carbohydrates relative to crude protein in perennial ryegrass in response to defoliation frequency

“…The effects of defoliation frequency could be mainly explained by the importance of WSC reserves for regrowth capacity after defoliation (Turner et al 2006;Donaghy et al 2008;Biligetu and Coulman 2011). Studies of carbon depletion in perennial ryegrass found a reduction of 43% in WSC reserves between plants defoliated at the 1-leaf and 3-leaf stages (Lee et al 2010).…”

Mixedgrass vegetation is tolerant to a short‐term but not season‐long access mat use during mitigation of industrial traffic

“…Access mats alter the environmental conditions regulating plant growth, including light, temperature, soil water, nutrients, and gas exchange (Woolhouse, 1983). The length of time a plant can withstand mat coverage, which block light and prevent photosynthesis, depends on stored carbohydrate reserves (Biligetu & Coulman, 2011) and associated species tolerance to these conditions, as well as the period of recovery before being subject to additional disturbance. Therefore, traits such as rapid regrowth, linked to the amount of non‐structural carbohydrates (Lardner et al, 2003), affect how quickly vegetation recovers after mat removal.…”