The use of water for rice irrigation in Rio Grande do Sul, Brazil, where the water courses are connected with the sea, may cause salt accumulation in the soil at harmful levels for the establishment of rice plants in the following years, especially when high rates of potassium fertilizer are applied in the plant rows. The study was carried out with the purpose of evaluating the effect of potassium chloride management on the establishment and absorption of cations by rice plants (variety IRGA 417) in a soil with different levels of sodium saturation. A Typic Hapludalf was used with sodium saturation of 5, 10 and 20 % and three potassium chloride managements: an amount of 120 kg ha-1 K2O broadcast; 120 kg ha-1 K2O in the row; 60 kg ha-1 K2O in the row; and a control without application of salt or fertilizer. The plant stand was unaffected by soil salinity or potassium chloride management. Soil salinity, however, affected plant ontogeny by delaying seedling emergence. Soil salinity above sodium saturation of 10%, inhibited K absorption, reduced seedling growth and reduced the ratio of K/Na, Ca/Na and Mg/Na in plant tissues. The interaction of fertilizer management vs salinity reduted the exchangeable Ca content in the soil, increased Na shoot content and reduted Ca/Na relation in rice shoots.
sodium saturation; Oryza sativa; potassium; calcium and magnesium
