采用基质培养法,用含3. 0、3. 5、4. 0、4. 5 和5. 0 g·L^-1 NaCl 的Knop 营养液进行胁迫处理,对5 个甜菊(Stevia rebaudiana Bertoni)品种幼苗的生长指标及其耐盐性进行了分析和评价。结果表明:在NaCl 胁迫条件下,5 个品种幼苗地上部分和地下部分的干质量、株高、根长、叶片数、叶片长度、叶片宽度以及主茎节数和分枝数等生长指标均低于对照,且随NaCl 质量浓度的提高总体上呈逐渐降低的趋势,但不同品种各指标的降幅存在明显差异。NaCl 胁迫对‘中山3 号’和‘守田2 号’幼苗地上部分和地下部分的干质量影响较小,对‘中山2 号’和‘守田3 号’幼苗地上部分和地下部分的干质量有较大影响。在NaCl 胁迫条件下,5 个甜菊品种幼苗的根冠比均大于对照;‘中山2号’和‘守田3 号’幼苗的根冠比随NaCl 质量浓度的提高呈先增大后减小的趋势,并在4. 0 g·L^-1 NaCl 胁迫条件下达到最大;其他3 个品种的根冠比均随NaCl 质量浓度的提高呈现缓慢增加的趋势。NaCl 胁迫对根长的抑制作用小于株高,对叶片长度的影响小于叶片宽度。相关性分析结果表明,甜菊幼苗的叶片数和分枝数与地上部分干质量的相关性显著,是导致地上部分干质量下降的重要原因。根据实验结果,供试甜菊品种按耐盐性从强至弱依次排序为‘中山3 号’、‘守田2 号’、‘中山4 号’、‘守田3 号’和‘中山2 号’,其中‘中山3 号’和‘守田2 号’耐盐性较强且各项生长指标均相对良好,可作为优良的甜菊耐盐种质资源进行深入研究。

Using Knop nutrient solution containing 3. 0, 3. 5, 4. 0, 4. 5 and 5. 0 g·L^-1 NaCl as treating solutions, NaCl stress treatments were conducted by matrix culture method, and some growth indexes and salt tolerance of seedlings of five cultivars of Stevia rebaudiana Bertoni were analyzed and evaluated. The results show that growth indexes of seedlings of all cultivars, such as dry weight of above-ground and under-ground parts, seedling height, root length, leaf number, leaf length and width, node number of main stem and ramus number, all are lower in NaCl stress condition than those in the control, and generally appear gradually decreasing trend with NaCl concentration rising, but there are obvious differences in decreasing range of all indexes among different cultivars. NaCl stress has a relatively small effect on dry weight of above-ground and under-ground parts of ‘Zhongshan No. 3’and ‘Shoutian No.2’, and has a relatively great effect on that of ‘Zhongshan No. 2’and ‘Shoutian No. 3’. Root/ shoot ratio of seedlings is all higher in NaCl stress condition than that in the control. In which, root/ shoot ratio of ‘Zhongshan No. 2’and ‘Shoutian No. 3’seedlings appears the trend of first increasing and then decreasing with NaCl concentration rising and reaches the highest in 4. 0 g·L-1 NaCl stress, while that of other three cultivars appears slowly increasing trend with NaCl concentration rising. The inhibition of NaCl stress to root length is smaller than that to seedling height, and that to leaf length is smaller than that to leaf width. The result of correlation analysis shows that correlation of leaf number and ramus number with dry weight of above-ground part of S. rebaudiana seedling is significant, indicating the two indexes are important reasons leading to dry weight of above-ground part decreasing in NaCl stress condition. On this basis, the five cultivar’s order of salt tolerance from strong to weak is ‘Zhongshan No. 3’, ‘Shoutian No. 2’, ‘Zhongshan No. 4’, ‘Shoutian No. 3’and ‘Zhongshan No. 2’. In which, both of ‘Zhongshan No. 3’and ‘Shoutian No. 2’have strong salt tolerance and relatively good growth indexes and can be further researched as S. rebaudiana germplasm resources with excellent salt tolerance.