|Author:||Ouda, S. A. ; El-Meseiry, T. ; Gaballah, M. S.|
|Book Group Author:||NA|
Two field experiments were conducted in Egypt in 2005 and 2006 growing seasons to collect data on soyabean biomass and yield to be used in validating the modified Yield-Stress model. Two soyabean cultivars, i.e. Giza 35 and Giza 82, were used. The total aboveground biomass was recorded at five growth stages (V4, R4, R6, R7 and R8). The Yield-Stress model was modified by adding a procedure to calculate dry matter production using solar energy level as the limiting factor. The model was validated using soyabean aboveground biomass measurements. Then, the model was used to predict soyabean biological and seed yields, in addition to consumptive water use. Furthermore, the model was used to assess the effect of deducting 10 and 20% of the total applied irrigation water on soyabean yields. The accuracy of the model was tested by calculating percentage difference between measured and predicted values, in addition to RMSE and Willmott index of agreement. The model adequately predicted soyabean aboveground biomass, biological and seed yields. Running the model under deducting 10 or 20% showed that Giza 82 was more tolerant to water stress than Giza 35. Under deducting 10% of the total irrigation, readily available water was completely depleted from the root zone after the 3rd, 4th, 5th and 7th irrigations and water stress was prevailing for 12 days, from V4 until few days before R6 growth stages and during the end of the growing season, where yield reduction was ~3.9%. Under deducting 20% of the total irrigation, yield reduction was 9.81% and readily available water was completely depleted after the 3rd irrigation until the end of the growing season (from V4 to R8). The easiness of using the model by non professionals could help in spreading the concept of deficit irrigation among Egyptian farmers. Furthermore, the model could help in scheduling deficit irrigation through avoiding sensitive growth stages to water stress, which could reduce yield losses.
|Pages:||827 - 834|
|Journal:||Research Journal of Agriculture and Biological Sciences|
crop growth stage, crop yield, cultivars, droughtresistance, dry matter accumulation, growth, irrigation water, models,plant water relations, soyabeans, water deficit, water stress, wateruse, yield forecasting, yield losses, Egypt, Glycine (Fabaceae), Glycinemax, North Africa, Africa, Mediterranean Region, Middle East, DevelopingCountries, Glycine (Fabaceae), Papilionoideae, Fabaceae, Fabales,dicotyledons, angiosperms, Spermatophyta, plants, eukaryotes, cultivatedvarieties, drought tolerance, soybeans, yield prediction, Field Crops(FF005) (New March 2000), Plant Breeding and Genetics (FF020), PlantWater Relations (FF062), Plant Production (FF100), Soil Water Management(Irrigation and Drainage) (JJ800) (Revised June 2002) [formerly SoilWater Management], Mathematics and Statistics (ZZ100)