Managing climate change impacts on crops: The influence of soil tillage on a triticale crop under water stress conditions

Abstract

Water limitations for agriculture will likely become crucial in the next decades in some regions such as the Mediterranean basin with the current climate change projections. In this context, recent evidence suggests that the application of conservation agriculture, which reduces the frequency and intensity of soil tillage, could confer a higher stability of agricultural systems against climate variability. However, not many experiments have addressed the interaction between tillage type and the resistance to drought in rainfed crops. In this work, we evaluated the resistance to drought of triticale (Triticale hexaploide L.) crops managed with different tillage systems: traditional tillage (TT), reduced tillage (RT) and no tillage (NT). A rainfall exclusion experiment was carried out in a typical wheat/legume Mediterranean rotation in SW Spain, in a long-term experiment established in 2008 comparing the three tillage systems. Grain yield and different variables related to plant ecophysiology, root development, biomass allocation and colonisation by arbuscular mycorrhizal fungi (AMF) were evaluated over one crop cycle. Tillage type had a significant influence on soil water storage (SWS), such that soils under NT had, on average, a 16% greater SWS than soils under RT or TT. Grain yield was significantly reduced by rainfall exclusion, in particular in the TT, where drought reduced grain yield by 31%. Gas exchange data also showed that plants in the TT system were more sensitive to drought, such that maximum photosynthesis rates were reduced by 25% because of rainfall exclusion in this tillage system. Drought had a negative impact on root biomass across the three tillage systems, especially in the RT, where a reduction in the root:shoot ratio was observed. The effect of tillage on mycorrhizal colonisation was more evident than the effect of drought; in general, conservation tillage systems (RT and NT) tended to have higher values for all AMF traits compared to the TT. In summary, the NT system tended to exhibit more favourable performance in terms of soil water retention, grain yield stability under drought conditions and mycorrhizal symbiosis, which suggests enhanced resource use efficiency in this system.