The irrigation management system affects disease incidence and grain yield of rice. This work was carried out aiming to study the effect of soil drainage periods during tillering on the progress of leaf and panicle blast (Pyricularia grisea) and grain yield of paddy rice grown with pre-germinated seeds. Four periods of water drainage were tested: no drainage, soil drainage at tillering and reflooding at 7, 14 and 21 days after soil drainage. Two cultivars were eva lu a t ed for ea ch ir r igat ion syst em: Epagr i 10 6 (short season) and Epagri 109 ( late season) . The cultivar 's disease reaction was evaluated during the growing seasons of 2004/05 and 2005/06, in Pouso Redondo, SC, Brazil. Blast severity on leaves and panicles was determined in seven samples, performed from 40 to 90 and 100 to 140 days after rice sowing, respectively. Data were used to estimat e the area under disease progress curve (AUDPC) of each cultivar. The water management system at tillering did not affect the area under disease progress curve (AUDPC) and grain yield. Smaller AUDPC values were presented by Epagri 106 for leaf and panicle bast. Grain yield ranged from 7.833 to 9.239 kg ha-1 (2004/2005) and from 3.984 to 9.040 kg ha-1 (2005/2006). High pluvial precipitation during the drainage periods prevented drought. This probably mitigated the effects of water management system on blast progress and rice grain yield.
Oriza sativa; irrigation; tillering; Pyricularia grisea; grain yield
