|Shewmaker, Glenn - UNIVERSITY OF IDAHO|
Submitted to: Western Society of Crop Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 31, 1999
Publication Date: N/A
Technical Abstract: Alfalfa accumulates total nonstructural carbohydrates (TNC) during daylight because photosynthesis produces more TNC than are metabolized for plant growth, maintenance and continued plant respiration. Our objectives were to: 1) determine diurnal variation of carbohydrate concentrations and accumulation rates in alfalfa (Medicago sativa L.), and 2) predict a time interval within which samples collected for carbohydrate analysis or animal preference could be compared effectively and avoid time of day effects. Germain 'Wll 322HQ' alfalfa was sampled at 3-h intervals during the 24-h period prior to cutting. Four cuttings were sampled and carbohydrate concentrations were determined. In May the TNC increased linearly from 9 am to 9 pm at 2.9 g TNC/kg DM/h (r squared = 0.90). Fresh alfalfa forage samples taken for animal preference or carbohydrate analyses should be taken within 1 h to control the diurnal variation effects to within 5% significance.