2.3 Measurements of total N and carbohydrates
content
Leaf-age, plant height and tiller numbers were measured at true leaf-age
four and six, respectively. Tiller occurrence percentage was calculated
as total tiller number divided by main stem number, reflecting plant
consistency at 4th true leaf emerging stage as each
plant usually has only one tiller. Plants were harvested at true
leaf-age six for biomass measurement (at 25-27 days post-seeding). The
plants were separated into leaf, sheath, and new-born tillers (with less
than 3 true leaves) for N content analysis using Kjeldhal method with an
automatic Kjeltec 8400 Analyzer Unit (Foss Analytical AB, Höganäs,
Sweden) following the manufacturer’s recommendations. For carbohydrates
measurement, plants were further separated into new-born tillers, leaves
(leaf positions 1-5), or sheaths (upper and lower parts). Carbohydrates
were measured by anthrone reagent (Zhang et al, 2019).