As the water resources in the central part of Iran (Isfahan) are being decreased and food security challenges are being faced, the preservation of the agriculture and dairy industry in this region has become more important. In this regard, this research was conducted in the form of three studies. The first study examined the effect of different soil suction thresholds before irrigation and crop rotation on the yield and water productivity of maize in loam soil under the drip-tape irrigation system. The three irrigation management levels contain; irrigation based on ETC calculation using FAO-PM equation (I1), soil moistures suction levels of 40 kPa (I2), and 20 kPa (I3), and two crop rotations containing; fallow-maize (Nfal) and wheat-maize sequence (Nseq). Total biomass (TB), leaf area index (LAI) during the growing season and grain yield (GY) at the maturity stage were measured. The maximum TB, GY, and LAI were observed in NfalW3 treatment with 25.047 tons/ha, 12.553 tons/ha, and 5.279 m2/m2, respectively. The difference between WPC (3.99 kg/m3) and WPI (3.88 kg/m3) was lowest in the I3, indicating precise irrigation based on the plant's water requirement and reducing evaporation and penetration losses. The objectives of the second study were to calibrate the Cropping System Model (CSM)-CERES-Maize for two maize hybrids and to eva‎luate the model under DTI with two different soil wetting widths. The single cross Hybrid 704 (SC704) grown in two experimental fields (Exp-1 and Exp-2) and the single cross Hybrid 606 (SC606) grown in one experimental field and two farmer fields (Exp-3, Ff-1, and Ff-2) were eva‎luated during three years (2016, 2017 and 2019). Plant traits including LAI, TB, soil moisture (SM), nitrogen uptake (NU), and water productivity (WPC) were measured. Soil NO3-N was measured at three distances from the planting row and three soil depths in Exp-1 and Exp-3 during two maize growth stages. The fraction of the wetted width (fw) along drip tape was 70% in Exp-1 and 100% in Exp-3 (referred to as fw-70 and fw-100, respectively). The results showed good performance of the model for simulating TB and LAI with NRMSE <21.9% and NRMSE <20.16% respectively for the two hybrids in the applied N fertilizer treatments. The accuracy of the simulation of SM and WP in fw-100 was better than that of fw-70. Simulated NO3-N followed the observed trend for fw-100, while model performance varied for the different irrigation and N levels in fw-70. Model accuracy for soil NO3-N prediction decreased for the high N fertilizer application under deficit irrigation management. These differences were related to the wetting pattern volume, the distribution of N in the soil profile, and the accumulation of soil N under DTI. In the third study, to provide the optimal planting date range, to investigate the yield potential and water productivity in the w agricultural lands of the Isfahan provinceand two calibrated cultivars SC606 and SC704 based on the detailed information of the investigated soil profiles. The yield and productivity of two mid-maturing and late-maturing hybrids were studied at the basin level.Therefore, it is important to pay attention to the amount of solar radiation during the growth period, soil texture and air temperature in choosing the appropriate place and date of corn cultivation with the highest yield and water efficiency.

مهدي قيصري

حميدرضا عشقي‌زاده، علي يوسفي، گريت هوگنبوم

محمد شايان نژاد، مرتضي زاهدي، محمدرضا نوري امامزاده‌ئي