Bases morfofisiológicas para diferenças de produtividade entre regiões produtoras de arroz irrigado em Santa Catarina

This work was carried out aiming to identity morphological and physiological bases that help to explain grain yielddifferences between two paddy rice production regions in Santa Catarina State (SC). Two field experiments were set, in thecities of Itajai and Pouso Redondo, SC, using the water-seed production system. Five genotypes were assessed at each place.Main stem leaf area, disease incidence, flag leaf chlorophyll content, grain yield and its components were measured. The fivegenotypes average productivity of grains was 11.4 t ha-1 in Pouso Redondo and 9.7 t ha-1 in Itajai. The number of grains perpanicle was the yield component that better explained productivity differences between experimental sites. The larger mainstem leaf area, the higher flag leaf chlorophyll content and the lower disease incidence were morpho-physiological traitsthat contributed to the higher productivities in Pouso Redondo. The greater solar radiation availability, the lower values ofmaximum air temperature and the smaller air relative humidity content are environmental factors that probably contributedto the higher grain yield of paddy rice in Pouso Redondo.