ABSTRACT


Juan Tosso T.1 y Jorge Tondreau A.1
 
An experiment was conducted during the years 1969-1973 at La Platina Experiment Station, Santiago, Chile. The main purpose of this study was to determine the evapotranspiration (ET) of sunflower and its relationship with pan evaporation (Ev) and crop yield (R). The total ET obtained was 706 milimeters with a peak value of 8.5 milimeters per day during the flowering stage.
A positive correlation between ET and Ev was found:
ET = -6.93 + 1.79 Ev
r = 0.90
The crop coeficients K, were determined for different stages of crop growth according to the equation:
K = ET/Ev
Finally, relationships between ET and grain yield, and between percentage of available water depleted in the first 30 cm of soil (Ha) and grain yield, were established with the following equations:
R = 8.35 + 0.40 ETr = 0.82 y 37≤ ET≤ 89R = 61.37 - 0.40 Har = 0.74 43≤ Ha≤ 93
Key words:
1Ings. Agrs. M.S., Programa Riego, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.