关键词: 城市化, 真实发展指标, 三大经济模式, 可持续性/可持续发展

Abstract: The study with rhizotron showed that the total length of tobacco’s second order lateral root had a much more increase than that of first order one,and the root length developed rapidly during 26～40 d and 56～70 d after transplanting for the second and first order lateral root,respectively.Before tip pruning,the branch root density of tobacco was decreased in order of 10～20＞0～10＞20～30＞30～40 cm soil layer.The branch density of main root was the highest in 7～21 cm soil layer.The deeper the soil layer,the bigger the ratio of dry weight and root length,but the distribution was reverse at 90 d after transplanting.The first order lateral root length density distributed in “S” curve in 0～10 cm soil layer and in double climax curve in 10～20,20～30 and 30～40 cm soil layers,while the second order lateral root length density became bigger with the course of growth period,which was in “S” curve in 0～10 cm soil layer and in single climax curve in other soil layers.

Key words: sustainability/sustainable development., three typical developmental patterns, genuine progress indicator, urbanization