海盐胁迫下苏牧2号象草幼苗不同器官中阳离子分配与运输

Cationic distribution and transportation in different organs of Pennisetum purpureum cv. Sumu No.2 seedling under sea-salt stress

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,10g/L海盐浓度胁迫后,苏牧2号根中Na+含量显著高于N51。4～10g/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4g/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 N51（CK）.Na＋ content increased but K＋,Ca2＋,Mg2＋ content and the ratios of K＋/Na＋ 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 in 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.