Citrus is one of the most important fruit crops for its rich nutrient and economic values. Citrus is mainly distributed over 135 tropical and subtropical countries. Water-stress which can disrupt crops' water balance and reduce production is a meteorological disaster that caused by long-term rainless or less raining. Even the area where rainfall is plentiful also easy involve in the drought disaster because of uneven rainfall and abnormal climate. Citrus is easier affected by water stress due to they mainly...