Soil properties, irrigation data, crop parameters, field conditions, and management parameters were used in AquaCrop simulation based on the calendar-day mode. Soil data were obtained from the local information (Zareian 2010). Daily measurements of temperature, humidity, and solar radiation were used in the model to determine daily crop evapotranspiration. We used the fully parameterized AquaCrop model that has been already calibrated and validated for wheat in the southern part of Iran (Andarzian et al. 2011). The conservative and non-conservative crop parameters are shown in Table 3. The parameterized AquaCrop model was used to simulate soil water content, CC, biomass, and grain yield for different wheat cultivars during the study period.
Conservative and non-conservative crop parameters used in the parameterized AquaCrop for wheat cultivars (Chamran, Mehregan, and Sirvan)
| Parameters . | Unit . | Chamran . | Mehragan . | Sirvan . |
|---|---|---|---|---|
| Conservative parameters | ||||
| Base temperature | °C | 0 | 0 | 0 |
| Cut-off temperature | °C | 26 | 26 | 26 |
| Canopy cover per seedling at 90% emergence (CC0) | % | 1.5 | 1.5 | 1.5 |
| Canopy growth coefficient (CGC) | % day−1 | 8.5 | 8.5 | 8.5 |
| Canopy decline coefficient at senescence (CDC) | % day−1 | 6.0 | 6.0 | 6.0 |
| Normalized water productivity (WP*) | g m−2 | 15 | 15 | 15 |
| Crop coefficient for transpiration at CC = 100% (KCTR,X) | – | 1.1 | 1.1 | 1.1 |
| Upper threshold of water stress for canopy expansion (Pupper) | – | 0.2 | 0.2 | 0.2 |
| Lower threshold of water stress for canopy expansion (Plower) | – | 0.65 | 0.65 | 0.65 |
| Shape factor for water stress coefficient for canopy expansion | – | 6 | 6 | 6 |
| Stomatal conductance threshold (psto) | – | 0.6 | 0.6 | 0.6 |
| Stomatal stress coefficient curve shape | – | 2.5 | 2.5 | 2.5 |
| Senescence stress coefficient (psen) | – | 0.70 | 0.70 | 0.70 |
| Senescence stress coefficient curve shape | – | 2.5 | 2.5 | 2.5 |
| Non-conservative parameters | ||||
| Maximum rooting depth | m | 1.5 | 1.5 | 1.5 |
| Minimum rooting depth | m | 0.3 | 0.3 | 0.3 |
| Maximum canopy cover (CCx) | % | 95 | 93 | 93 |
| Plant density | Plants m−2 | 120 | 110 | 110 |
| Referenced Harvest Index (HI0) | % | 42 | 43 | 45 |
| Time to emergence | day | 12 | 10 | 12 |
| Time to flowering | day | 93 | 95 | 95 |
| Length of flowering stage | day | 10 | 12 | 12 |
| Time to senescence | day | 100 | 110 | 105 |
| Time to maturity | day | 142 | 145 | 145 |
| Parameters . | Unit . | Chamran . | Mehragan . | Sirvan . |
|---|---|---|---|---|
| Conservative parameters | ||||
| Base temperature | °C | 0 | 0 | 0 |
| Cut-off temperature | °C | 26 | 26 | 26 |
| Canopy cover per seedling at 90% emergence (CC0) | % | 1.5 | 1.5 | 1.5 |
| Canopy growth coefficient (CGC) | % day−1 | 8.5 | 8.5 | 8.5 |
| Canopy decline coefficient at senescence (CDC) | % day−1 | 6.0 | 6.0 | 6.0 |
| Normalized water productivity (WP*) | g m−2 | 15 | 15 | 15 |
| Crop coefficient for transpiration at CC = 100% (KCTR,X) | – | 1.1 | 1.1 | 1.1 |
| Upper threshold of water stress for canopy expansion (Pupper) | – | 0.2 | 0.2 | 0.2 |
| Lower threshold of water stress for canopy expansion (Plower) | – | 0.65 | 0.65 | 0.65 |
| Shape factor for water stress coefficient for canopy expansion | – | 6 | 6 | 6 |
| Stomatal conductance threshold (psto) | – | 0.6 | 0.6 | 0.6 |
| Stomatal stress coefficient curve shape | – | 2.5 | 2.5 | 2.5 |
| Senescence stress coefficient (psen) | – | 0.70 | 0.70 | 0.70 |
| Senescence stress coefficient curve shape | – | 2.5 | 2.5 | 2.5 |
| Non-conservative parameters | ||||
| Maximum rooting depth | m | 1.5 | 1.5 | 1.5 |
| Minimum rooting depth | m | 0.3 | 0.3 | 0.3 |
| Maximum canopy cover (CCx) | % | 95 | 93 | 93 |
| Plant density | Plants m−2 | 120 | 110 | 110 |
| Referenced Harvest Index (HI0) | % | 42 | 43 | 45 |
| Time to emergence | day | 12 | 10 | 12 |
| Time to flowering | day | 93 | 95 | 95 |
| Length of flowering stage | day | 10 | 12 | 12 |
| Time to senescence | day | 100 | 110 | 105 |
| Time to maturity | day | 142 | 145 | 145 |