Comparison among Four Temperate Grasses in Production Structure at Each Heading Stage

Abstract

Each one clone sward of timothy (TM), orchardgrass (OR), reed canarygrass (RC) and tall fescue (TF) grown for two years was used to compare the production structure at each heading stage when the initial harvest was cut at 10 and 0cm height and to trace the following dry matter and protein production with 4 and 5 cutting frequency during the season. Two types of production structure were recognized ; TF and OR, which had a greater leaf distribution towards the base of plant, and RC and TM, which had a relatively uniform vertical distribution of leaf. These leaf distribution was associated with the number and the variance of internode length. Total nitrogen concentration of both leaf-blade and leaf-sheath plus stem was highest at the top of canopy, declining gradually towards the base. TAC concentration of leaf-sheath plus stem, on the contrary, gradually increased towards the base, especially high near the ground surface, mostly due to the accumulation of fructosan. TF and OR, TM and RC, respectively, are also similar in vertical trend of concentrations and contents of these substances. TF contained much nitrogen in the leaf-sheath plus stem, while RC accumulated much of it in the leaf-blade, OR and TM were intermediate in this respect. Sol-N/Tot-N ratio gradually increased towards the base, while Total sugar/Fructosan ratio decreased towards the base in RC and TM. In TF and OR it was highest at the top or at the middle of canopy. Dry matter and CP yields at the initial harvest were TM>OR>RC>TF in order when cut at 10cm level, but TF yielded more than RC when cut at 0cm level. The regrowth during 3 weeks after the initial harvest cut at 10cm level was TF>OR>RC>TM in order. The total yield during the season of dry matter and CP was higher when cut at ground surface than cut at 10cm level, probably because of less freqency of cutting with enough rest period after the initial harvest. The highest yield was obtained in RC cut at 0cm level, because of higher growth rate at the latter part of the season due to vigorous regrowth from rhizomes.