To what extent arbuscular mycorrhiza can protect chicory (Cichorium intybus L.) against drought stress

Water deficiency is one of the most significant limiting factors resulting in severe crop yield reduction. This study hypothesizes that the inoculation of arbuscular mycorrhiza (AM) minimize the detrimental effects of drought in chicory (Cichorium intybus L.). The objective was to evaluate how AM inoculation affects agro-biochemical traits of chicory under different irrigation rates. Field experiments were conducted in 2017 and 2018 in north of Iran and designed as a factorial combination of three irrigation rates [40, 65 and 90 % of maximum allowable depletion of available soil water (IR1, IR2 and IR3, respectively)], two AM inoculations [inoculated and not inoculated (AM+ and AM−, respectively)] and two chicory ecotypes [Sefid Isfahan and Siyah Shiraz (E1 and E2, respectively)]. Crop growth, pigments and minerals content, carbon exchange rate, transpiration rate and stomatal conductance were evaluated. The data showed that the mycorrhizal colonization increased chicory growth performance by 12.4 %, 16.1 % and 21.0 %, under I1, I2, and I3 water regime, respectively. The mineral content and photosynthesis parameters decreased as irrigation water decreased, irrespective of whether plants were inoculated or not. Similarly, AM+ plants had higher inulin percentage and the mean inulin degree of polymerisation than AM− plant under all of irrigation levels. Furthermore, inoculated chicory plants under drought stress showed an enhanced activity of the antioxidant system, such as superoxide dismutase, peroxidase, ascorbic acid and glutathione, while the accumulation of hydrogen peroxide and the oxidative damage were reduced. The two ecotypes tended to respond similarly to irrigation and AM treatments for all growth and quality parameters measured in the experiment, even if ecotype Siyah Shiraz performed better than ecotype Sefid Isfahan. The improved plant performance and inulin content in the inoculated plants demonstrate that AM has the potential to minimize the detrimental effects of drought stress on chicory under semi-arid conditions.