**2. Some ecophysiological response of blueberry grown under different water regimes**

Blueberries (*Vaccinium* spp.) usually prefer well-drained, moist, acidic sandy loam soils with high organic content. It can tolerate moderate drought but is sensitive to soil waterlogging [1]. Inadequate or excessive soil water supply attenuates the growth and development of blueberry and makes a negative effect on both yield and fruit quality. Among the myriad of management measures for blueberry culture, scientific and reasonable water management is particularly critical [2]. Clarifying the water physiological characteristics and water requirement of blueberry is a precondition for development of water-saving and efficient irrigation schedule. Therefore, water physiology and water requirement of different types of blueberry at different growth stages under different soil and climatic conditions have been extensively studied [3–7]. Results from previous studies showed blueberry water requirements vary with plant age and cultivar, weather and soil conditions, and cultural practices [8–14]. Consequently, water demand of blueberry under different climate and soil conditions should be appropriately adjusted and revised according to local condition.

Soil types in Changjiang (Yangtze) river basin region are red soil and yellowbrown soil, which are heavy clay with poor drainage. Moreover, there are not only heavy rain days but also drought days in summer and autumn due to monsoon climate. Therefore, soil permeability improvement by soil amelioration and soil moisture regulation by precision irrigation are the key measures of blueberry cultivation in this region. Because of the different soil texture and climate conditions, it is necessary to study the water stress tolerance and water requirement of major blueberry cultivars based on local experiments in this region. It has been found that types of blueberries that best suited to grow in Yangtze river basin region are rabbiteye (*Vaccinium ashei*) and southern highbush (*V. corymbosum*). In this study, changes in growth indexes and photosynthetic characteristics of rabbiteye blueberry seedlings after drought or flooding stressed for 14 days and recovering normal water supplying were analyzed and compared. Effects of different irrigation regimes on seedling growth and water consumption pattern of "Brightwell" rabbiteye blueberry and "Misty" southern highbush blueberry were investigated. The relationship between actual water requirement of blueberry seedlings and water surface evaporation was studied, and the water requirement model based on water surface evaporation was established. Recommendations for optimum irrigation management of blueberry grown in southern China were drawn accordingly.
