Abstract: Morus alba has strong capacity of waterlogging tolerance. We examined the growth characteristics and ecophysiological responses of 4-year-old fodder-potted Morus alba seedlings under waterlogging stress. Plant height and the number of adventitious roots of M. alba seedlings were measured at regular intervals under four water conditions: control (CK), shallow waterlogging (QY), semi-waterlogging (BY), and deep waterlogging (SY). The changes of physiological indices of M. alba seedlings, including SPAD value, osmotic adjustment substances (soluble sugar, soluble protein, proline) and malondialdehyde (MDA) were analyzed at different waterlogging durations. The results showed that plant height of M. alba seedlings in the four treatments increased to different degrees in the waterlogging process. The increase of plant height in CK and QY was significantly higher than that in BY and SY during 20 to 60 days of waterlogging. After 10 days of waterlogging, a few adventitious roots began to appear at the base of the stem in each waterlogging group. At the end of waterlogging, the number of adventitious roots produced in BY was higher than that in SY. The SPAD value of leaves in waterlogging groups decreased signi ficantly after waterlogging. After 60 days of waterlogging, the SPAD value in QY, BY, and SY reached the minimum, with a reduction of 59.65%, 62.37% and 64.91% respectively. In the early stage of waterlogging, foliar soluble sugar contents in waterlogging groups increased significantly. With increasing waterlogging duration, foliar  soluble sugar content in waterlogging groups decreased, but still higher than that in CK. After 60 days of waterlog ging, there was no significant difference in soluble sugar content between QY and CK, but the content increased by 34.61% and 13.65% in BY and SY respectively. Waterlogging significantly increased foliar contents of soluble protein, proline, and MDA. After 60 days of waterlogging, the contents of the three substances in BY and SY were significantly higher than those in CK. Our results indicated that M. alba seedlings could adapt to waterlogging environment by forming adventitious roots and increasing the content of osmotic adjustment substances.

Key words: forage mulberry seedling, flooding stress, chlorophyll content, osmotic adjustment substance.