Mathematics models are able to simulate realistically the growth and the phasic development of cultures under wide range of environmental and management conditions, with a low cost. The objective of this work was to investigate the effects of the sowing time in the management and yield of the corn "out season", Londrina County - PR, Brazil, by long period simulations using the CERES model. The treatments consisted of 12 sowing times simulations, from January to April under two different scenarios: without water limitation (potential production) and with water limitation, being assumed a precocious cycle cultivar, XL-520, for 24 years. The results showed decreases of yields of up to 38% in the potential productivity and of 44% in the productivity under water restriction to the late sowings due to the coincidence of the critical periods of development with sub-great temperature, water and solar radiation conditions. Increases were observed in the cycle duration of 120 to 140 days when the corn was sowed in January, and of 160 to 170 days for sowing in April. The longest cycle influences in the sequence of cultivations, and sowings after the 3o sowing time of March only will allow the cultivation of the Summer culture after October. There was also tendency of increasing the establishment risks in the cultivation, due to the water deficiency, as the sowing was being late. There is a frost risk of 4% for the cultivation sowed in end of March and of 8% sowed in April.
mathematical model; irrigation; modeling
