Irrigated areas require intensive cropping to maximize use of land and irrigation systems. Rice has a high potential for crop rotation in areas with sprinkler irrigation in northern Paraná State, Brazil, because of its high response to water supply, high potential yield, and compatible phenological cycle with other crops. Potential grain yield, water requirements, and duration of crop cycles were determined for two upland rice cultivars (IAPAR 9 e IAPAR 64), sown at two planting dates (October, 5th and December, 1st) and maintained under three water regimes (non irrigation and irrigation at tensions equal to 25 and 70 kPa). Grain yield was high for sowing in October (5400 to 6000 kg ha-1) and lower for sowing in December (1600 to 4800 kg ha-1) due to the low temperature at seed filling stages, mostly for the late cultivar (IAPAR 64). No significant differences between irrigated treatments were observed, but water deficit caused a grain yield decrease of up to 50% and delayed flowering. As a conclusion from these results, upland rice was considered highly appropriate for crop rotation in irrigated areas of Paraná.
Oryza sativa; irrigation; date of sowing
