Comparative study of winter cereals forage productivity in Mediterranean agro-system highlight possibilities for crop improvement and agronomic diversification

Context: Understanding the interaction between genotype performance and environmental conditions is crucial for selecting resilient, productive crops, especially in the context of climate change. In the Mediterranean basin, cereal forage production is highly vulnerable to drought and heat stress, with yield losses varying by location, stress severity, and crop choice. It is therefore essential to compare the biomass productivity of various cereal crops as potential wheat alternatives for forage in Mediterranean and semi-arid climates. Objective: To compare the dry matter yield (DMY) and related traits of four winter cereal forage crops across five environments supplemented by varying levels of irrigation. Methods: Thirteen varieties of winter cereal forage crops were grown in the field under different supplementary water regimes during 2013–14 (one environment), 2014–15 and 2015–16 (two environments each). The cereal forage crops were evaluated for phenology, leaf area index (LAI), dry matter accumulation (DMA) (at different time points), number of tillers, plant height (PH), water use efficiency (WUE) and DMY at the soft dough stage. In addition, relative growth rates (RGR) served as an indicator of biomass productivity. Results: Growth and DMY parameters of winter forage cereal crops were significantly influenced by environment and crop type. Additionally, a strong interaction effect between crop genotypes and environment was detected for almost all traits, except for RGR, LAI and DMY. The highest DMY at the soft dough stage was recorded in oat (2.8–2.2 kg m⁻²), followed by barley (2.0–1.7 kg m⁻²), late-phenology wheat (1.9–1.5 kg m⁻²) and triticale (1.9–1.5 kg m⁻²). Early-phenology wheat varieties, which are the dominant commercial winter forage crops under Mediterranean environments, exhibited the lowest productivity (1.6–1.3 kg m⁻²). Significant contributions of early RGR to WUE were noted in a semi-arid environment. As expected, water availability significantly increased DMY at the soft dough stage, with increments ranging from 17 % to 21 % for early phenology wheat to 36–43 % for oats. Conclusions: Water availability was the primary environmental DMY driver. In addition, number of tillers per meter square was identified as the main driver of biomass build-up. Interestingly, this driver was consistent across environments and all crops except for oat at Env1. Implications: These results highlight the promising potential of barley, triticale and oat for diversification of the current Mediterranean winter forage agro-system dominated by wheat monoculture. Furthermore, investing in traits such as early-stage RGR and tiller number for breeding programs, could further enhance forage productivity and system resilience.