Table 3. Tolerance index (TI) in three S. integra varieties after 14 days of exposure to increasing concentrations of Pb.

	Varieties
Pb treatment (µM)	Yizhibi	Weishanhu	Dahongtou
47	95.80±4.50a	89.20±5.90a	79.91±10.04a
123	81.37±9.09ab	85.83±9.38ab	76.69±15.92a
178	80.92±1.76ab	82.72±12.89ab	70.43±2.32a
196	66.87±9.72b	73.15±15.83b	62.78±2.54a

Values are mean ± S.D. (n = 6), and data with different letters in the same column indicate a significant difference at P<0.05 according to Fisher's LSD test.