Abstract:

Crop growth modeling, which was developed very quickly in recent decades, is a forceful tool in scientific research. Many crop growth models, such aful tool iries, WOFOST and RZWQM and the like, have been developed and applied widely, but few of them have been introduced in China. This research was aimed at evaluating the suitability of WOFOST model for the North China Plain. WOFOST is a mechanistic crop growth model developed by Wageningen Agricultural University, the Netherlands. It was summarized briefly and then validated by using experimental data in North China Plain. This experiment was conducted in two successive years (2000-2001) in Yucheng Comprehensive Experiment Station, the Chinese Academy of Sciences (CAS), located at Yucheng, Shangdong Province of China. Water treatment pools have eight water treatments with two replicates: 1) treatments 1-5: water was supplied close to 40%, 50%, 60%, 70%, 80% of field water capacity; 2) treatment 6: water stress was set from turning green to shooting; 3) treatment 7: water stress was set from earring to filling; 4) treatment 8: water stress was set from filling to harvest. Each treatment was under a movable rain-shelter. Water content was measured using a neutron probe every five days; an additional measurement was taken before and after rainfall and irrigation. Crop growth was examined every five days, including tiller number, leaf area index, fresh and dry weight of all organs, filling rate and plant height. Leaf area was measured by LI-3100. The model was calibrated to get values of parameters using the experimental data in the year 2001, and then it was validated by data in 2000. The following crop growth simulation results (on a per-hectare basis) were examined: potential production, water limited production, potential total above-ground dry matter and water limited total above-ground dry matter, potential and water limited leaf area index, potential and water limited stem weight. Comparison between measured values and simulated results shows their correlation is close. The main conclusions of this study were as follows: 1) WOFOST model is suitable for similar research in North China Plain. It describes crop photosynthesis in detail and is good at simulating crop potential growth; 2) WOFOST treated some aspects simply and often uses a simple formula instead of a complex one to simplify input; 3) the potential production in North China Plain is about 8 100 kg·hm-2 and present production achieves only about 65% of this; 4) WOFOST has some problems that need to be improved. It disregards dry matter transportation from leaves and stems to seeds and describes dry matter partitioning too simply.