Best sowing dates for rice, <em>Oryza sativa</em>, in the state of Paraná, Brazil

Abstract

The identification of regions within the state of Paraná, southern Brazil, with homogeneous characteristics of water deficit for the rain-fed rice crop, Oryza sativa (Poaceae) and the use of criteria to determine the best sowing periods for these regions are provided. Research was based not only on the historical data from field experiments in which sowing dates were evaluated for several localities, but also on meteorological information from IAPAR-managed network. Records were used to calculate the risks of water deficit during plant establishment and flowering. In the case of the region North of Paraná there is a very high risk of water deficit. The average frequency risk at flowering is over 50%. In the southern areas of the same state, the risk at flowering lies between 20 and 50%, with periods of lower risk for sowings in October and November. These are the most indicated months for sowing