Simulation of herbage yield and growth components of Cock’s foot (Dactylis glomerata L.) in Jablje using the calibrated LINGRA-N model | Simulacija pridelka zelinja in komponet rasti navadne pasje trave (Dactylis glomerata L.) v Jabljah z umerjenim modelom LINGRA-N

anglais. 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.

slovène. Predhodno umerjen model LINGRA-N smo uporabili za simulacijo pridelka suhega zelinja (GRASS) in komponent rasti navadne pasje trave (Dactylis glomerata L.) v 50-letnem obdobju (1964–2013) v Jabljah. Izkazalo se je, da so se v drugi polovici obravnavanega obdobja pri simulacijah GRASS na letni ravni začeli pojavljati osamelci. GRASS je bil najmanjši v letih 1992, 1993 in 2003. To so tudi najbolj suha leta, tako na podlagi meteoroloških spremenljivk kot tudi na podlagi simuliranega faktorja zmanjšanja rasti zaradi suše. Potencialni pridelek (YIELD) ni linearno odvisen od meteoroloških spremenljivk. Določene komponente rasti smo na dnevni skali primerjali v sušnem letu 1993 in povprečnem 1994. V letu 1993 je bilo na primer prestreženega fotosintetsko aktivnega sevanja 53 %, v letu 1994 pa 75 %. Razvoj stanja vode v tleh tekom leta smo povezali z razvojem indeksa listne površine ter posledično z razvojem mase zelenih listov, mase korenin, mase odmrlih listov in GRASS. Rezultati opozarjajo na pomembnost nadaljnjih raziskav, tako poljskih poskusov kot tudi modelskih simulacij. Pri slednjih se moramo zavedati, da nosijo s seboj negotovosti iz različnih virov.