Modelling non-structural carbohydrates in forage grasses with weather data
1999
Wulfes, R. | Nyman, P. | Kornher, A.
A weather-based dynamic model was formulated to simulate the concentration of water-soluble carbohydrates(WSC) in harvestable dry matter of forage grasses. The main aim of the model development was to describe and quantify the response of photoperiod(daylength), incoming shortwave radiation, air temperature and plant-available soil water on WSC content in a simple functional approach with widely available weather data. In co-operation with a regional of national agrometeorological service, farmers can, in the future, get information about the WSC content of their herbage in order to optimize the cutting date for pastures and temporary grassland due to the demands of animal nutrition and silage management. The response of meteorological factors on WSC content was modelled in two steps. Firstly, the general trend of WSC content was calculated, describing indirect weather effects on WSC content concerning phenological development of the plants. Secondly, direct influences of weather factors on WSC content were added, reflecting photosynthesis and respiration processes on a short time scale. The modelling approach was parameterized on a set of data from northern Germany, which were collected daily in different growing periods in the years 1990, 1991 and 1994 in stands of Lolium perenne L. The model fitted the WSC content of the presented data with a mean root mean square error of 2.74% units (cv: 11.3%). The potential of the model is discussed in relation to weather sensitivity and adaptability to different genotypes, sward types and nitrogen fertilization levels.
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