The objective of this paper was to compare between agro-climatic zones developed from 10-year interval of weather data from 2005-2014, 20-year interval of weather data from 1995-2014 and the zoning developed by [NORELDIN et al. 2016] using 30-year interval from 1985-2014 in the old cultivated land of Egypt in the Nile Delta and Valley. Monthly means of weather data were calculated for each year, and then monthly values for 10-year and 20-years were calculated for each governorate. Basic Irrigation scheduling model (BISm) was used to calculate reference evapotranspiration (ETo). Analysis of variance was used and the means was separated and ranked using least significant difference test (LSD0.05). Our results showed that agro-climatic zoning using 20-year values of ETo was similar to the zones developed with 30-year values of ETo, with different values of average ETo in each zone. Furthermore, using 10-year values of ETo resulted in higher values of ETo in each zone, compared to 20-year and 30-year ETo values. However, the average value of ETo over the three classifications was close to each other. Thus, depending on the availability of weather data, either zoning can be sufficient to develop agro-climatic zones.

In many areas of the world, water shortages prevail and threaten food production. Deficit irrigation was commonly investigated in dry areas as a precious and sustainable production approach. Using the CropSyst model to simulate the effects of different deficit irrigation treatments could help draw conclusions and save time, effort, and money. Therefore, the aims of this research were (i) to calibrate and validate the CropSyst model for wheat under different sustained and phenological stage-based deficit irrigation treatments, (ii) to simulate the impacts of the latter treatments on limiting wheat yield reduction. Two field experiments were conducted in Nubaria (Egypt), representing an arid environment. They included seven irrigation treatments: (1) 100%, (2) 75%, or (3) 50% of crop evapotranspiration (ETc) during the whole crop cycle; (4) 50% ETc at tillering only, or (5) at booting only, or (6) at grain filling only, or (7) at both tillering and grain filling, with the replenishment of 100% ETc to the treatments (4) to (7) in the remaining phenological stages. The results revealed that phenological stage-based deficit irrigation of wheat resulted in lower yield reduction compared to sustained deficit irrigation treatments, with a 6% yield reduction when 50% ETc was applied at the booting stage. Wheat yield loss was reduced to 4 or 6% when 95 or 90% of ETc were applied, respectively. The CropSyst model accurately simulated wheat grain and total dry matter under deficit irrigation with low RMSE value. In conclusion, the CropSyst model can be reliably used for evaluating the strategy of planned deficit irrigation management in terms of wheat production under the arid environment.

A field experiment was conducted during the 2018/2019 wheat growing season in Kafr El-Sheikh Governorate. This is to assess the potential impact of climate change on wheat production under different irrigation treatments using the DSSAT-CERES wheat simulation model and climate change scenarios; to determine the best sowing date to be used as an adaptation strategy under climate change scenarios. The model effectively simulates wheat yield, with a high goodness of fit and d-Stat value, and low root mean square per observation, resulting in an overall goodness of fit of average 13.8 kg/fed. The model's performance was satisfactory, with high R² and d-Stat values and low RMSE/obs, with overall values of 0.830, 0.951, and 2.3 mm, respectively for water consumption. The CERES-Wheat model accurately simulates wheat yield and water consumption, allowing us to assess climate change's impact on wheat yield in 2030 and 2040. The study shows a decrease in solar radiation (SR) by 1.9 and 2.1 MJ/m²/day in 2030 and 2040, while maximum temperature increases by 1.5 and 1.9°C due to climate change, and minimum temperature decreases by 1.8 and 2.3°C in 2030 and 2040. This results in an increase in potential evapotranspiration (PET) by 0.2 and 0.3 mm. The study predicts that season length will shorten in 2030 and 2040 due to temperature increases. In 2030, it will be reduced by 2, 4, and 4 days under different treatments. In 2040, it will be lower, with reductions of 3, 5, and 5 days. The study found that wheat yield losses would be lowest under the first sowing date and irrigation treatment, while the highest reductions were found under the third treatment. Climate change will reduce wheat water consumption due to shorter growing seasons and heat stress, with the lowest reductions occurring in 2030 and 2040 at 8 and 18%, respectively. The highest reductions in wheat yield were observed under the third sowing date and irrigation treatment. We suggest planting wheat in November, using full irrigation to prevent high-yield losses, and implementing adaptation strategies to reduce wheat plant vulnerability to climate change risks.

The objectives of this study were to calibrate CropSyst model for fodder beet grown under full and late season drought and to use the simulation results to analyze the relationship between irrigation amount and yield, as well as in water management to reduce yield losses under full and late season drought. For this reason, two field experiments were implemented at El-Serw Agricultural Research Station in Demiatte governorate, during 2011/12 and 2012/13 growing seasons. Two irrigation treatments were studied: full irrigation and late season drought. The model was calibrated using the data obtained from the two seasons. Results indicated that the reduction in fodder beet yield under late season drought was 11 and 12% in 2011/12 and 2012/13 growing seasons, respectively. Calibration of CropSyst revealed that the percentage of difference between measured and predicted values were low in both growing seasons. The results also indicated that changing irrigation schedule after examining water stress index under full and late season drought led to increase in fodder beet yield, as well as water and land productivity. Thus, CropSyst model can give insight into when to apply irrigation water to minimize yield losses under late season drought.