Tiller production in cocksfoot (Dactylis glomerata) and tall fescue (Festuca arundinacea) growing along a light gradient

Abstract

Pasture managers seek to balance leaf appearance with utilization to sustain sward productivity while meeting livestock nutritional needs. Achieving this in silvopasture must account for the influence of light and defoliation on tillering. We determined tiller production, as a function of light availability and clipping height, for two forage grasses adapted to cool, humid temperate conditions of the Appalachian region of the USA. Tiller production of cocksfoot (orchard grass) (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) was greatest in unshaded and least in shaded sites, irrespective of residual clipping height. Juvenile plants produced more than twice as many tillers as mature plants, with differences accentuated by site, reflecting a shift in reproductive and resource-use strategies. Trends in tiller production were as follows: cocksfoot > tall fescue; 10-cm > 5-cm residual clipping height; and unshaded > partially shaded > densely shaded sites. Tiller production reaches maximum earlier in the woodlot site, regardless of species or clipping height, than at the unshaded site. Plants at the wooded site extended leaves quickly, sustaining herbage production, but had less non-structural carbohydrate and fewer tillers. Cocksfoot, but not tall fescue, sustained leaf and tiller production in the shaded sites, suggesting that cocksfoot is suited for use in silvopasture in this region.

Relationship between sward height and herbage mass for integrated crop‐livestock systems with trees

“…However, multiple simultaneous stresses occur in ICLS with trees in the form of resource competition between trees and the understory crop community (Belesky et al . ). For instance, in general, herbage production decreases as light intensity decreases, due to reduced photosynthesis and modification of leaf and tiller morphology (Cavagnaro and Trione ; Soares et al .…”

“…These responses lead to a low root:shoot ratio and weakened plants with less leaf total non‐structural carbohydrate and fewer tillers relative to plants growing in the full sunlight system (Belesky et al . ; Gommers et al . ).…”

“…The incorporation of the tree component in NT-ICLS may contribute to increase the productivity of these diverse farming systems, as well as the potential attainment of ecosystem services, such as improving soil structure, soil organic carbon (C) sequestration, nutrient cycling and welfare (Yates et al 2007). However, multiple simultaneous stresses occur in ICLS with trees in the form of resource competition between trees and the understory crop community (Belesky et al 2011). For instance, in general, herbage production decreases as light intensity decreases, due to reduced photosynthesis and modification of leaf and tiller morphology (Cavagnaro and Trione 2007;Soares et al 2009;Abraham et al 2014).…”

“…Many grasses adjust to shade by increasing leaf length and specific leaf area to increase light acquisition (Shipley and Almeida-Cortez 2003;Gommers et al 2013), allowing plants to meet the target height quickly. However, at the same time they slow tiller production in order to allocate photosynthate to existing tillers rather than to new tiller buds (Cavagnaro and Trione 2007;Belesky et al 2011). These responses lead to a low root: shoot ratio and weakened plants with less leaf total nonstructural carbohydrate and fewer tillers relative to plants growing in the full sunlight system (Belesky et al 2011;Gommers et al 2013).…”

“…However, at the same time they slow tiller production in order to allocate photosynthate to existing tillers rather than to new tiller buds (Cavagnaro and Trione 2007;Belesky et al 2011). These responses lead to a low root: shoot ratio and weakened plants with less leaf total nonstructural carbohydrate and fewer tillers relative to plants growing in the full sunlight system (Belesky et al 2011;Gommers et al 2013). Consequently, shading by trees can alter the relationship between SH and HM by changes in sward structure.…”