Simulating grain yield and plant development of ratoon grain sorghum over diverse environments

Crop simulation may provide an inexpensive means to evaluate the feasibility of different cropping practices to optimize productivity and profitability. One practice, ratoon-cropping, may increase productivity and reduce per-unit production costs associated with conservation tillage farming systems in tropical and subtropical regions. sorkam, a dynamic plant growth model for grain sorghum [Sorghum bicolor (L.) Moench], was used to evaluate the potential of rainfed ratoon grain sorghum over diverse climatic regions of Texas. Eleven independent data sets collected in the U.S.A. from sites in Georgia and Texas were used to determine the model's accuracy. The model produced realistic estimates of grain yield for planted, ratoon, and combined (planted + ratoon) crops. Simulated grain yields usually were within 25% of the observed yield for the planted, ratoon, and combined crops with cultivars that produced the highest ratoon grain yield at each location. Ratoon grain yield results of multi-year simulations (10–30 years) from 14 locations over the eastern half of Texas using historic, location-specific, meteorological data indicated that the probability of obtaining ratoon grain yield > 3.0 Mg/ha was confined to the upper coastal plain region of Texas. The area best suited for rainfed ratoon grain sorghum appeared to be confined south and east of a line running from west of Corpus Christi to Beeville to College Station to west of Center, Texas. Use of crop models can play an important role in identifying strengths and weaknesses of potential cropping systems when used in combination with historical climatic data and/or computer weather generators.