对不同浓度[0(CK)、50 和100 mmol·L^-1 ]NaCl 胁迫条件下菊芋(Helianthus tuberosus L.)幼苗的生长、叶片光合作用参数以及体内Cl^- 、Na⁺和K⁺含量分布状况进行了比较研究。结果表明,随NaCl 浓度的提高,菊芋幼苗单株地上部分的鲜质量和干质量以及全株鲜质量和干质量均逐渐下降且均与对照差异显著(P<0. 05);地下部分的鲜质量和干质量也呈逐渐下降的趋势,但仅100 mmol·L^-1 NaCl 处理组与对照组间有显著差异(P<0. 05)。随NaCl浓度的提高,叶片的净光合速率(Pn)和气孔导度(Gs)逐渐减小、水分利用效率(WUE)和气孔限制值(Ls)逐渐增大,但总体上差异不显著(P>0. 05);50 和100 mmol·L^-1 NaCl 处理组的Pn 分别为对照组的85. 6%和44. 9%,Gs 分别为对照组的67. 9%和57. 1%,WUE 分别为对照组的1. 25 和1. 54 倍,Ls 分别为对照组的1. 57 和1. 64 倍。随NaCl 浓度的提高,菊芋幼苗地上部分和地下部分的Cl- 和Na+ 含量逐渐增加、K⁺ 含量逐渐减小,且各处理组间Na+含量差异显著、K⁺含量差异不显著;地上部分和地下部分的Na+ / K⁺比均随NaCl 浓度的提高逐渐增大,0、50 和100mmol·L^-1 NaCl 处理组幼苗地上部分的Na⁺ / K⁺比分别为0. 26、0. 83 和2. 39,地下部分的Na⁺ / K⁺比分别为0. 51、1.16 和2. 83;各处理组幼苗地上部分的Cl^- 、Na⁺和K⁺ 含量均明显高于地下部分,表明地下部分吸收的Cl^- 、Na⁺ 和K⁺大部分被转移至地上部分。研究结果显示,NaCl 胁迫对菊芋幼苗生长和叶片光合作用等均有一定的抑制作用,对其体内离子平衡也有一定的影响,干扰了菊芋幼苗的正常生长。

Growth, leaf photosynthetic parameters and Cl^-, Na⁺ and K⁺ of distribution status in Helianthus tuberosus L. seedlings were studied under NaCl stress with different concentrations of 0 (CK), 50 and 100 mmol·L^-1. The results show that fresh and dry weights of above-ground part and whole seedling all decrease gradually and have significant differences compared with the control group (P<0. 05), and also those of under-ground part appear gradual decreasing trend but only has a significant difference between 100 mmol·L^-1 NaCl treatment group and the control group (P<0. 05). With NaCl concentration rising, net photosynthetic rate (Pn) and stomatal conductance (Gs) of leaf decrease gradually, while water use efficiency (WUE) and stomatal limitation (Ls) increase gradually, but generally, all differences of the four indexes are not significant among different treatment groups (P> 0. 05). In 50 and 100 mmol·L-1 NaCl treatment groups, Pn is 85. 6% and 44. 9%, Gs is 67. 9% and 57. 1%, WUE is 1. 25 and 1. 54 times and Ls is 1. 57 and 1. 64 times of their respective control group. In above-ground and under-ground parts of seedlings, contents of Cl^- and Na⁺ increase gradually while K⁺ content decreases gradually with NaCl concentration rising, and the difference of Na⁺ content is significant but that of K⁺ content is not significant among different treatment groups. Na⁺ / K⁺ ratios of above-ground and under-ground parts all increase with NaCl concentration rising, and under 0, 50 and 100 mmol·L^-1 NaCl stress, Na⁺ / K⁺ ratio of above-ground part is 0. 26, 0. 83 and 2. 39 and that of under-ground part is 0. 51, 1. 16 and 2. 83, respectively. Contents of Cl-, Na+ and K+ of above-ground part are all obviously higher than those of under-ground part in different treatment groups, showing most of Cl^-, Na⁺ and K⁺ absorbed by under-ground part being transferred to above-ground part. It is concluded that NaCl stress has some inhibition to growth and photosynthesis, and also influences on ion balance in H. tuberosus seedling, therefore, disturbs normal growth of H. tuberosus seedlings.