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

Abstract

ABSTRACTHerbage dry matter (DM) yield of grasses is a function of the density and size of vegetative (VEG), generative (GEN), and elongating vegetative (ELONG) tillers. We determined the contribution of these three tiller types to DM yield accumulation along with their main morphological characteristics on three sampling dates during each of the primary growth and the regrowth of field‐grown swards of timothy (Phleum pratense L.) and tall fescue (Festuca arundinacea Schreb.). Our results provide the first quantitative characterization of ELONG tillers, which contributed to timothy DM yield by up to 28% in primary growth and 58% in regrowth. In tall fescue, VEG tillers were dominant in primary growth and regrowth (74 to 100% of DM yield). The GEN tillers were dominant (67 to 74% of DM yield) in the primary growth of timothy while in the regrowth, VEG tillers were dominant early (84% of DM yield) but ELONG tillers represented 58% of DM yield later on. Timothy and tall fescue had similar rates of DM accumulation. The greater DM yield on all sampling times of the regrowth of tall fescue confirms a greater growth before the first sampling, most likely due to the greater proportion of VEG tillers. The GEN tillers were large with low leaf to weight ratio (LWR) and proportion of attached senesced material whereas VEG tillers were small with high LWR and large proportion of attached senesced material. The ELONG tillers were intermediate in size and LWR but they had a low proportion of attached senesced material.