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Root growth and spatial and temporal distribution in the 0-100 cm soil profiles of three common annual halophytes Salsola subcrassa,Suaeda acuminate and Petrosimonia sibirica distributed in a saline desert in northern Xinjiang,China were studied in 2009 and 2010.The results showed that the root systems of the three halophytes were of the taproot type,vertically distributed in the 90-cm soil profile,and were deepest in late July.Their taproots reached maximum depth rapidly,early in the growth period,but with rare lateral roots.They were then dug out in an orderly way,from bottom to top,exhibiting vertical development first and then horizontal development.The distribution of specific root length,which reflects the characteristics of the feeder root,was gradually increased from top to bottom,whereas root weight displayed an opposite distribution pattern.The root length distribution of the three halophytes was concentrated (62％ to 76％) in the middle soil profile (20-60 cm),with less distribution in the surface (0-20 cm) and bottom (60-90 cm) soil profiles.The results indicated that the roots of the three annual halophytes grew rapidly into the deeper soil layer after germination,which ensured the plant survival and uptake of water and nutrition,and thus built up a strong tolerance to an arid,high-salt environment.