Agrophysiological responses of bread wheat to raised-bed planting and irrigation level

To investigate the response of wheat to drought stress under different plantation systems, two field experiments were carried out in 2021/22 and 2022/23 in Arsanjan, Iran. The main plot was three different plantation systems (flat planting, 60, and 120 cm raised beds) and the sub plots were irrigation levels at 100% (control), 80% (medium stress), and 60% (severe stress) of crop evapotranspiration. Raised bed planting increased grain yield by 24% compared to flat cultivation. This increase for biological yield was about 17%, the number of ears was 7%, and the number of seeds per ear was 21%. Drought stress caused a significant decrease in grain yield (46.4%), number of ears (20.5%), seed number (30.3%), biological yield (45.9%), chlorophyll a (31.8%), chlorophyll b (28.1%) and relative water content (5.3%) and increased, proline content (24.3%) and ion leakage (147.3%). Water use efficiency was increased in raised bed planting and deficit irrigation treatments. The decrease in yield due to drought stress was moderated to some extent in the raised bed system and therefore cultivation on raised beds is suggested as a suitable planting pattern to improve yield and WUE in wheat under conditions similar to the experimental area, especially under water shortage conditions.