Plant Maturity and Cutting Frequency Effect on Total Nonstructural Carbohydrate Percentages in the Stubble and Crown of Timothy and Orchardgrass1
- P. Mislevy,
- J. B. Washko and
- J. D. Harrington2
Concentration of total nonstructural carbohydrates (TNC) in perennial bunch-grass stubble is an indicator of its physiological condition. However, there is little information connecting management systems with stubble carbohydrate reserves. The object of this study was to evaluate the influence of initial harvest and subsequent height of regrowth at cutting on TNC levels in the stubble and crown of ‘Climax’ timothy (Phleum pratense L.) and ‘Pennlate’ orchardgrass (Dactylis glomerata L.). Firstgrowth was harvested at: transition (changing of apical meristem from vegetative to reproductive growth), boot (flower head emergence), or anthesis stage. After initial harvest, regrowth was harvested at 10. to 15-, 20- to 25-,30- to 36-, 41- to 46-, or 51- to 56-cm plant heights.
Both grasses had low TNC percentages (4 to 5%) at their transition stage. Delaying initial harvest of timothy until boot or anthesis stage increased stubble and crown TNC percentages four to five times.
Delaying initial harvest of orchardgrass to boot stage had little effect on stubble and crown TNC percentages. However, stubble-crown reserves increased 5 percentage points when initial harvest was delayed to anthesis. With frequent harvesting of both grasses, TNC percentages remained low, but the trends of TNC increased as the frequency of harvest decreased. By early November both species had a high stubble and crown TNC percent. age regardless of the regrowth harvest schedule. Stubble and crown TNC percentage was generally lower by the following spring for all treatments, with orchardgrass exhibiting the greatest decrease. These data indicate that the seasonal trend of stubble and crown TNC accumulated by each grass species reflects the harvest management system imposed during that growing season.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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