Combination of sowing date with deficit irrigation for improving the profitability of carrot in a tropical environment (Brazil)

• This paper shows the simulation of carrot crop under tropical conditions.
• The most sensitive stage for water deficit is vegetative development.
• FAO 33 and 56 methodologies were adopted.
• The combination of sowing date with ORDI may increase the profitability and save water.

This study was conducted to determine the most suitable irrigation strategy for improving the water productivity of carrot in Rio de Janeiro (Brazil) by using two sowing dates (June 16th and August 3rd). Experimental data from a two-year field test were used for calibration (2010) and validation (2011) of the simulation of carrot with the MOPECO model under deficit irrigation conditions. In 2010 and 2011 for no-deficit conditions the net irrigation was around 150 and 180 mm in the 1st and 2nd sowing date, respectively. The maximum yield was about 64,000 kg ha−1. The root mean square error (2790 and 2968 kg ha−1) and the relative error (5.3 and 4.9%) values show good fit between the simulated and observed treatments for 2010 and 2011, respectively. Depending on the water stress target, the use of the optimized regulated deficit irrigation in the study area would increase carrot yield by up to 7% and 15% compared with the a constant deficit irrigation strategy for the two proposed sowing dates under the climatic conditions of 2012. In economic terms, the gross margin reached 6849 and 5881 € ha−1 for the first and second sowing dates, respectively.