Simulation of herbage yield and growth components of Cock’s foot (Dactylis glomerata L.) in Jablje using the calibrated LINGRA-N model

Abstract

In the study the previously calibrated LINGRA-N model was used for a long term simulation (1964–2013) of the herbage  dry matter yield (GRASS) and growth analysis of Cock’s foot (Dactylis glomerata L.) in Jablje. Changes in the yearly  GRASS variability are reflected in the appearance of outliers in  the second half of the study period. The biggest reductions in GRASS are seen in the years 1992, 1993 and 2003. These are  the driest years according to meteorological variables (high  maximum and minimum air temp eratures, low precipitation)  and also according to the simulations, with the lowest  reduction factor for crop growth due to drought. The potential  yield (YIELD) is not linearly dependent on meteorological  variables. Some growth compone nts were compared on a daily  basis in a dry year (1993) and an average year (1994). In 1993, for instance, 53 % of photosynth etically active radiation was  intercepted, against 75 % in  1994. Seasonal development of  the actual soil moisture content was linked to the development  of the leaf area index and consequently to the mass of green  leaves, to the roots mass, to the mass of dead leaves and to  GRASS. The results highlight the need for further research, on  field and with simulations. As re gards the latter, we have to  keep in mind that they inevitably involve various  uncertainties.