THE ROLE OF LEVELS IRRIGATION AND DDFICIT IRRIGATION TREATMENTS ON CONSUMPTIVE WATER USE, GROWTH AND YIELD OF Vicia faba L.

Abstract

Abstract : Field studies were conducted for scheduling full and deficit irrigation of Vicia faba L. under water tension in autumn season 2010-2011 at field experiment in Agricultural Research Station of Abu-Graib- Baghdad, Iraq , 20 km west of Baghdad ( the location lies on longitude 33 22 north and latitude 44 24 and 34 m above sea level). The objective of the study was to estimate the crop water requirements and water use efficiency. The experimental design was split plot in RCBD with three replications. The main plots were for water tension and sub- plot for full and deficit irrigation treatment (control S0, and deficit irrigation included omitting one irrigation at branching S1, flowering S2, beginning pod S3 and beginning seed stage S4). Faba bean cultivars were in main plots planted in 10th October 2010 and harvested in 10th April 2011 irrigation was imposed at 50% depletion of available water. Amount of required irrigation water use to estimated actual evapotranspiration depending on water balance equation, reference evapotranspiration from modified Penman Montieth equation, and evaporation from class-A-pan. Results show the deficit irrigation caused significant differences in actual evapotranspiration between the full irrigation and deficit irrigation treatments. Actual evapotranspiration (ETa) for the full irrigation treatments significantly increased by 4.3, 6.5, 9.2, 9.2 and 7.4, 11.6, 11.6, 14.7 and 4.7, 5.9, 5.9, 8.2% of S1, S2, S3, S4 respectively in 100%, 75% and 60% depletion of field capacity. The water tension reduced of actual evapotranspiration by 21.6, 29% in 75% and 60% compared 100% treatment. The value of reference evapotranspiration (ET0) was calculated using Penman-Montieth modified equation and pan-A recorded 561, 860 mm, respectively, while the actual evapotranspiration recorder 525, 433 and 405 mm in 100%, 75% and 60% depletion of field capacity. The highest water use efficiency was obtained from 75% treatment 1.59 kg/m3. Water stress caused reduction in plant height, No. of branches/plant, biological yield and seed yield values by 5and 15; 10 and 31; 8 and 15; 25 and 48; 3 and 19% 75% and 60% depletion of field capacity, respectively.