Estimation of Consumptive Water Use of Vicia faba Under Conditions of middle of Iraq – Kut city

Abstract

Experiment field was conducted for irrigation scheduling depending on moisture depletion of available water for leguminosae in field of agriculture college-Wasit University at latitudes 32° 30′ 31.19″North and longitudes 45° 26′ 89″ East, Altitude 19 m through the autumn season 2016-2017 in loam soil. the aim of this study to determine the reference water consumptive ETo , actual consumptive use ETa , crop coefficient Kc of leguminosae and water use efficiency at irrigation scheduling on base of moisture depletion of available water at ratios 25, 50 and 75% and effect of climate factors on it. The experiment carried out using random complete block design (RCBD) with three replicates. The seeds of leguminosae planted at date 10/10/2016, the end of growth season at 15/4/2017. The quantities of added water used to calculate the actual consumptive use ETa by using water-balance equation, the gravimetric water content determined immediately after irrigation and before the following irrigation through the growth season to limit irrigation scheduling of studied treatments. The reference water consumptive ETo calculated by using three empirical equations (Blaney-criddle, Najib Kharrufa, Evaporation pan). The results showed that the Najib Kharrufa equation gave high value of ETo 675.49 mm comparatively with equations of evaporation Pan and Blaney–criddle that gave ETo values 591.92 and 544.77 mm alternately. The treatment of irrigation at depletion of 25% of available water gave high value of ETa 577.95 mm, comparatively with treatments depletion of 50 and 75% of available water that gave ETa values 531.5 and 472.1 mm, alternately. The results showed increasing of crop coefficient Kc, for all treatments, with progress of growth season and reached high value at flowering and spuds formation stage and reduced at maturation stage (end of growth season), the high value of Kc showed at irrigation treatment at depletion 25% of available water, its ranged between 0.62 to 1.44, but the low value of Kc showed at irrigation treatment at depletion 75% of available water, its ranged between 0.38 to 1.29. The irrigation treatments showed significant differences between studied characteristics crop , thus irrigation treatment at depletion 25% of available water increased significantly in comparison with irrigation treatment at depletion 75 % of available water in height plant and leaf area surface , but there are non-significant differences were noted in stem diameter , the irrigation treatment at depletion 25% of available water increased significantly in comparison with other treatments in total yield (spuds) . The irrigation treatment at depletion 50% of available water gave high water use efficiency (WUEf) that equal 1.43 kg m-3.