Leaf dynamics of timothy and meadow fescue under Nordic conditions

Abstract

Leaf production dynamics of timothy (Phleum pratense L. cv. Tarmo) and meadow fescue (Festuca pratensis Huds. cv. Kalevi) were studied in Finland under field conditions in mixed swards containing timothy, meadow fescue and red clover (Trifolium pratense L. cv. Björn) harvested by cutting. Fifteen randomly selected tillers of both species were marked and leaf number, leaf appearance rate (LAR), leaf elongation rate (LER), leaf senescence rate (LSR) and leaf live span (LLS) were followed through weekly observations. Concurrently another set of fifteen tillers of each species was dissected on each occasion to determine the number of unemerged leaves and development stage of the apex. The first observation period was between 26 April and 22 June and the second between 22 July and 22 September. The species differed clearly for most of the measured parameters but most differences were dependent on the season. In spring, timothy started growth earlier, had higher LAR (+57%), produced more leaves (+83%) with higher LERgross (+58%), higher LSR (+61%), higher LERnet (+54%) and produced larger tillers (+193% in leaf area) than meadow fescue. In autumn, timothy still had a higher LAR (+80%), produced more leaves (+60%) with higher LERgross (+36%), but had also a higher LSR (+77%) and thus similar LERnet (0%) to meadow fescue. Timothy tillers were only slightly larger than meadow fescue tillers (+20% in leaf area). The consequences of these findings on competition in mixed swards and implications for grazing theories are discussed.

Tiller Characteristics of Timothy and Tall Fescue in Relation to Herbage Mass Accumulation

“…This difference between our observations in the regrowth (proportion of senesced material between 0.22 and 0.36) is largely explained by the lower sampling height (0 cm) in our study. Although the leaf life span is reported to be shorter for timothy (266–465 growing degree days) (Bélanger, 1996, 1998; Virkajärvi and Järvenranta, 2001) than for tall fescue (550 growing degree days) (Lemaire, 1988), the amount of senesced material was similar for both species. To our knowledge, there are no published values of the proportion of senesced material for different tiller types.…”

“…This could be related to the generation of new ELONG tillers with a high proportion of living leaf blade in timothy and of new VEG tillers in tall fescue. Although the physiology of leaf senescence is well established (Bélanger, 1996;Woodward, 1998;Virkajärvi and Järvenranta, 2001), the proportion of senesced material is seldom reported. The observed values in the primary growth (0.12-0.19) were slightly greater than those reported for timothy in the United Kingdom by Terry and Tilley (1964) (0.04-0.15) for approximately similar growth periods.…”

Dynamics of structural traits in two competing C3grass species: influence of neighbours and nitrogen

“…Meanwhile, the lack of increases in tiller size (i.e. shade‐tolerance response; Figure a) by means of neighbour effects is aligned with the fact that tiller size increases are observed in shaded canopies (Casal et al ., ; Virkajärvi and Järvenranta, ). This is not the case during the canopy establishment phase, because, in this period, it was not possible to fulfil all the stages of the processes of competition for light (Lemaire, ) when the light interception was ≤93% of the incident light.…”

“…The lower number of expanded leaves of intermediate‐age tillers of plants flanked by BW neighbours probably induced the decrease in tiller density (Figure c and Table ). This early restriction of horizontal space occupation led by annual neighbours is of great importance during the pasture establishment and/or when the canopies are slightly dense (Virkajärvi and Järvenranta, ). In this sense, tillering represents an exploitation or opportunist response (Nelson, ) Obviously, it conditions the future community composition (Ross and Harper, ; Eagles et al ., ).…”

“…Total green lamina length per tiller (cm tiller −1 ), a tiller size estimator (Berone and Dreher, ; Berone et al ., ,b, ), was the weekly average of green lamina length per tiller, including both expanded and growing leaves (Virkajärvi and Järvenranta, ; Agnusdei and Colabelli, ; Berone et al ., ,b; Berone and Dreher, ). Pseudostem height (cm tiller −1 ) was the distance between the highest visible ligule and the soil surface (Virkajärvi and Järvenranta, ). Tiller density (tillers plant −1 ) was the number of tillers per target plant at final harvest (109 das; 85 dae; 56 daf).…”