Water Use Efficiency of No Tillage Wheat in Semiarid Argentina.

In the semiarid pampa of Argentina wheat will grow during most of its cycle with the water stored at sowing time, while during yield determination will increase the possibilities that the plants will grow under water stress.

Under this situation the wheat cycle and the crop management that make a better use of the water in the soil profile will get the best yield. The water use efficiency (WUE) can be improved by different management practices.

Our objective was to evaluate water use and WUE on yield components with wheat cultivars of different cycle and under different row distance.

Wheat cultivars of long, intermediate and short cycle sown at appropiate time were used. Row distances used were 0,175; 0,35 and 0,525 m.

Soil water content, evapotranspiration (ET) and total dry matter was measured at different times. Water use efficiency, harvest index, yield and yield components were also determined.

The evapotranspiration was highest with an intermediate cycle and lowest with a short cycle wheat. There were no differences in ET under different row spacings.

The largest yield and WUE were obtained with an intermediate cycle at the shortest row distance: 4521 kg ha^-1 and 12,0 kg mm^-1, respectively.