DETERMINATION OF CROP COEFFICIENT (KC) OF POTATO (SOLANUM-TUBEROSUM L) FOR SANTA-MARIA, RS, SOIL-CLIMATIC CONDITIONS

The crop coefficient (Kc) has been determined for potato (Solanum tube rosum L.), under sprinkler irrigation, as well the total evapotranspir ation in the cycle for Santa Maria, RS, soil-climatic conditions. The reference evapotranspiration has been esteemed as from evaporation of the Class A pan and the maximum evapotranspiration through the water b alance method. The lower limit of water tension in the soil was 45 kPa , inside of the maximum productivity range. The crop coefficients obta ined were: 0,51; 1,43; 1,14; 1,01; and 0,89 in the P2, P3, P4, P5, and P6 subperiod, respectively. It was concluded that the crop coefficien t values found resembled with those recommended by the FAO (Doorenbos & Kassan) 1979).