以象草苏牧2号和N51(对照)为材料,研究了不同海盐浓度胁迫下幼苗根、茎和叶中Na+、K+、Ca2+和Mg2+含量随胁迫时间延长的分配与运输规律.结果表明,苏牧2号和N51植株各部分Na+含量均随海盐浓度的升高而升高,K+、Ca2+、Mg2+含量和K+/Na+均随海盐浓度的升高而降低.随胁迫时间的延长,10 g/L海盐浓度胁迫后,苏牧2号根中Na+含量显著高于N51.4～10 g/L海盐浓度胁迫后,苏牧2号茎中Na+含量总体上显著低于N51,叶中Na+含量苏牧2号均低于N51,但不同胁迫时间下差异不尽相同；苏牧2号根、茎中K-含量总体显著高于N51,苏牧2号和N51叶中K+含量高低则不尽相同；苏牧2号叶中K+/Na+总体显著高于N51；苏牧2号的SK+/Na+(茎/根)除4 g/L处理后第7天苏牧2号低于N51外,苏牧2号均高于N51,是其运输系数的1.02～2.19倍.表明苏牧2号的SK+/Na+(茎/根)高,使得根系能截留更多的Na+和向茎选择性运输更多的K+,提高茎中K+/Na+,同时其叶片中保持了高K+/Na+,从而减小植株受盐害程度,是苏牧2号耐盐性比N51增强的原因之一.%With prolonged stress time under different sea-salt concentrations, Na+ , K+ , Ca2+ , Mg2+ distribution and transportation in roots, stems and leaves of Sumu No. 2 Napier grass seedlings were analyzed and compared with those of N5KCK). Na+ content increased but K , Ca2+ , Mg2+ content and the ratios of K+/Na1 decreased in all organs of Sumu No. 2 and N51 as the sea-salt concentration increasd. With increasing time under 10 g/L sea-salt concentration stress, the Na+ content in roots of Sumu No. 2 was higher than those of N51. Under 4-10 g/L sea-salt concentration stress, the Na+ content in stems of Sumu No. 2 was significantly lower than that of N51, and that in leaves of Sumu No. 2 was lower than in N51; the K+ content in roots and stems of Sumu No. 2 was significantly higher than those of N51, while the K+ content in leaves of Sumu No. 2 and N51 were not the same; The ratios of K+/Na+ in leaves of Sumu No. 2 were higher than in N51; The transport selectivity of SK+ /Na+ (stem/root)of Sumu No. 2 was 1. 02-2. 19 times that of N51, except that Sumu No. 2 was lower than that of N51 after 7 d stress with 4 g/L sea-salt concentration. It appears that a major characteristic of the salt tolerance mechanism m Sumu No. 2 seedlings is a high transport selectivity of SK+/Na+ (stem/ root)that can intercept more Na+ in roots and selectively transport more K+ from root to stem resulting in a higher K+/Na+ ratios in stems and leaves under sea-salt stress.
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