The transpiration of Mexipak wheat (Triticum aestiviumL.) in central Iraq

Abstract

SUMMARYThe actual transpiration of Mexipak wheat (Triticum aestiviumL.) was determined by the inflow-outflow method and by soil moisture determination by the use of a neutron probe and gravimetrically. Three irrigation treatments were used during the 1969 season, wet, medium and dry. Amounts of water given were 370, 310 and 255 mm for wet, medium and dry treatments respectively. One irrigation treatment was used during the 1971 and 1972 seasons in which 620 and 700 mm of water respectively was given. However, during the 1973 season, two wet irrigation treatments of 560 and 670 mm of water were used. Values ofEtmeasured by different methods were closely related. Seasonal averages ofEtwere 2·55, 1·99 and 1·62 mm/day for wet, medium and dry treatments respectively. The empirical coefficient (f = Et/Eo) under wet treatment, was found to be higher than that given by Penman (1956) for short grasses and higher than that obtained by Boumanset al.(1963) for wheat and barley in Iraq. The empirical coefficientKbin the Blaney-Criddle formula was less than the value given by Blaney & Criddle (1950) for an arid climate and less than the value obtained by Boumanset al.(1963) for wheat in Iraq. The water use efficiency for grain production was greater under dry than under wet treatment.