Tea is one of the most consumed beverages worldwide, cultivated in nearly 64 countries. Although a significant amount of water is required for proper growth of tea plant, excessive moisture or waterlogging conditions are detrimental to tea yield and quality. Waterlogged conditions in tea hinder root respiration, accumulate toxic metabolites and alter several physiological descriptors such as leaf yellowing, stomatal closure restricting photosynthesis, leaf senescence, wilting and oxidative damage. Plants immediately respond to waterlogging stress by adapting their morphological structure, such as promoting adventitious root development and aerenchyma formation, or by regulating their defence system, for instance, triggering the accumulation of osmoprotectants and enhancing antioxidant activities to facilitate normal plant functioning. Most of the current research have concentrated on how tea plants respond to waterlogging, but there is a lack of information on the in-depth mechanisms behind the responses. Again, unlike other crop perspectives, crop improvement studies to overcome this issue are also severely insufficient. This review discusses morphological, physiological and biochemical reactions of tea plants to waterlogging stress, with a hypothetical possible mechanism behind the responses. Many possible opportunities are suggested to boost waterlogging tolerance through modern and conventional breeding approaches. This paper also mentions some knowledge gaps, providing future research thrusts with systemic critiques of present studies.
