Cistus species can form ectomycorrhizae and arbuscular mycorrhizal fungus that can bring benefits when plants are under water stress conditions. However, the application of some ectomycorrhizae on the water uptake under drought through physiological traits and hormonal regulation is less known. The experiment was performed during three months in a growth chamber with Cistus albidus plants in which the combined effect of the ectomycorrhiza Pisolithus tinctorious inoculation and two irrigation treatments (control and water-stressed plants) were applied. Irrigation absence caused significant decrease in aerial growth and tended to decrease soil water potential at the root surface, leading to a decrease in leaf water potential. Under these conditions, the abscisic acid and salicylic acid content increased while the precursor of ethylene decreased. Although the mycorrhization percentages were not high, the inoculation of P. tinctorious improved the water status and slightly cushioned the rise in leaf temperature of water-stressed plants. The ectomycorrhiza decreased the scopoletin values in leaves of plants subjected to deficit irrigation, indicating that inoculated plants had been able to synthesize defense mechanisms. Therefore, Pisolithus tinctorious alleviated some of the harmful effects of water scarcity in Cistus plants, being its use a sustainable option in gardening or restoration projects.

Under Mediterranean irrigated conditions cover cropping (CC) and double cropping (DC) are diversification/intensification strategies that can increase grain yield and resource use efficiency of the traditional winter fallow‐maize ( Zea mays L.) system. Four cropping systems were evaluated in terms of productivity, water and nitrogen use efficiency (WUE and NUE) under sprinkler‐irrigated conditions during three growing seasons in the Ebro Valley, Spain: (1) long‐season maize with winter fallow (F‐LSM), (2) long‐season maize after a leguminous cover crop (common vetch, Vicia sativa L.) (CC‐LSM), (3) short‐season maize after a cereal crop (barley, Hordeum vulgare L.) (B‐SSM), (4) short‐season maize after a leguminous crop (winter peas, Pisum sativum L.) (P‐SSM). The introduction of the vetch winter cover crop required an additional 5% irrigation water but allowed to reduce the nitrogen fertilizer applied by 20%, increasing the system grain yield synthetic nitrogen use efficiency (NUEsynt‐g) by 27% without affecting the cropping system grain yield and WUE. DC systems required 12% more irrigation water than the traditional F‐LSM but produced more grain. The B‐SSM was the most productive system (21.9 Mg grain ha ⁻¹ ) and increased the WUE by 32% compared to the F‐LSM system, but required a 39% more nitrogen fertilizer. Compared to the traditional F‐LSM system, the P‐SSM cropping system increased the grain yield (+16%), protein yield (+66%), NUEsynt‐g (+20%), and the WUE (+10%). The diversification and intensification of the traditional F‐LSM system increased yield (with the DC systems) and resource use efficiency (WUE with the DC systems; NUE with CC‐LSM and P‐SSM cropping systems).

Management of legume cover crops to reduce their cost by using no-tillage and reducing seed rate could increase their adoption. Despite the growing interest in cover crops, no information exists simultaneously regarding the potential of different species and how the sowing method and seed rate affect nitrogen (N) contribution and the yield of the subsequent maize crop. During a four-year field trial, under irrigated conditions in the Ebro valley (NE Spain), three leguminous cover crop species (pea, common vetch and hairy vetch), two cover crop seeding methods (conventional tillage and no-tillage) and two seeding rates (normal and 25% reduced) were tested and compared with a control treatment without a cover crop. The aboveground cover crop biomass and the N derived from biological fixation (BNF); aboveground biomass and total N in weeds; soil mineral nitrogen; and the effect on maize grain yield and N content were evaluated. Pea and common vetch produced more biomass (+76%) and had a higher N uptake (+50 to 60%) compared to hairy vetch. The sowing of the cover crops after no-tillage combined with a reduced sowing rate reduced biomass production by 14%. The percentage of nitrogen derived from the atmosphere (Ndfa) was above 60% for all species and the differences in total N derived from biological fixation (BNF) among treatments were related to the aboveground biomass. The introduction of cover crops reduced weed growth compared to the control especially in the no-tillage treatment. Cover crops increased maize grain yield by 12% and N uptake by 17% compared to the control treatment without a cover crop.