Short-term responses of root morphology to drought stress of Cotinus coggygria seedlings from four varied locations in northern China.

Short-term responses of root morphology to soil drought stress in Cotinus coggyria seedlings gathered from four locations in northern China ( Xishan Mountain and Yanqing County in Beijing, Taishan Mountain in Shandong Province and Jiangxian County in Shanxi Province) were studied in the field. The results indicated that: 1) C. coggyria seedlings adapted to continuous drought stress by altering their root morphology. The root tip number, root fork number, root surface area and average root diameter of C. coggyria seedlings treated with severe stress were higher than those of control by 46.5%, 15.5%, 3.4%, 8.6%, respectively, and they were also higher than those of seedlings continuously treated with moderate stress by 90.5%, 34.2%, 15.6%, 18.4%, respectively. 2) Fine roots at a diameter of 0.0 ~0.5 mm were more sensitive to soil water stress than any other sizes of roots, presented as the length and tip number of fine roots increased, accounting for 54.7% ~93.5% and 95.1% ~99.5% of total root during continuous drought stress treatments. 3) The recovery growth of roots after restoring irrigation in seedlings from four different locations was remarkably different. The relative root biomass of seedlings from Jiangxian County of Shanxi Province subjecting to the moderate drought stress treatment and then restoring irrigation was 29.0 and 48.6 times of those of seedlings from Xishan Mountain andYanqing County of Beijing, and it was 280% higher than that of seedlings from Xishan Mountain of Beijing when subjecting to severe drought stress and then restoring irrigation. Thus, the seedlings from Jiangxian County of Shanxi Province are more sensitive to soil drought stress, but they have stronger recovery ability after restoring irrigation than others.