Co-application of Chitosan and Ascorbic Acid Alleviated Drought Stress in Common Chicory (Cichorium Intybus L.) by Improving Physiological and Biochemical Changes

Although the positive role of chitosan and ascorbic acid (AsA) in modulating drought stress has been discovered in plants, there is no available data on their co-application on medicinal plants under water limitation. The present study aimed to discover the effect of chitosan and AsA on plant growth and physio-biochemical attributes of common chicory (Cichorium intybus L.) at different irrigation regimes. A split plot factorial experiment was carried out with the main plot of irrigation regimes at 60 mm, 90 mm, and 120 mm evaporation from Class A pan as normal irrigation, moderate, and severe drought, respectively, and foliar application of chitosan (50 mM and 100 mM) and AsA (4 mM) in the subplots during 2020 and 2021. The results showed that without chitosan and AsA, severe drought stress led to decreased shoot yield (59%), root yield (32%), chlorophyll (Chl, 30%), relative water content (RWC, 20%), saturated fatty acid (SFAs, 23%), and monounsaturated fatty acids (MUFAs, 12%) but increased electrolyte leakage (EL, 23%) and polyunsaturated fatty acids (PUFAs, 10%) compared with normal irrigation. However, the interactions of chitosan and AsA with an adjusting role in drought improved the growth and biochemical attributes. Total phenolic content (TPC) in plants exposed to moderate drought and sprayed with chitosan at 50 mM or AsA was higher than other treatments. The heat map showed that TPC and shoot yield represented the high variability during the experiment, which can be determined as indicators for discovering the physiological and biochemical changes in common chicory. The present work suggested the co-application of chitosan at 50-100 mM and AsA at 4 mM can alleviate drought stress on common chicory in arid and semiarid areas.