Simulation of Optimum Sowing Dates for Dry-bean Cultivated in Central Region of Brazil

There are three growing seasons of drybean (Phaseolus vulgaris) in Brazil; dry season, winter season and wet season, with sowing dates between February to May, April to July and, October to December, respectively. The objective of this study was to determine the optimal sowing dates for each of the three growing seasons in Central Brazil using crop model simulation. The Decision Support System for Agrotechnology Transfer (DSSAT 3.5) CROPGRO - Drybean was used as a growth and development simulator for drybean. The model was calibrated using drybean cultivar ‘BRS Esplendor’, planted on 15 December 2011 in Tangará da Serra, MT. Climate data including, maximum and minimum air temperature, solar radiation, precipitation, and plant phonological and soil parameters during the season were used in model calibration. Following a satisfactory calibration, simulations were performed for six sowing dates within intervals of 15 days for the three seasons. A historical dataset of 6 years of weather data was used for this simulation. The wet season showed overall higher grain yield compared to the other two seasons. The December 1 sowing date resulted in 3,301 kg ha^-1, while the highest yield for the dry season was 3,018 kg ha^-1 for the February 1. Total grain yield were drastically reduced with planting dates between February 15 and April 1 compared to December sowing. The dry bean sowed between April and August resulted in the lowest grain yield, with yield below 473 kg ha^-1. The reduced yield was result of a low rainfall during the crop cycles, which was the main factor influencing the leaf area index. In conclusion, dry bean sowing dates in the wet season between December and mid-February showed the highest yield potential. Dry and winter season sowing required irrigation to achieve maximum dry bean yield.