盐碱胁迫对香樟幼苗离子吸收与分配的影响

Effects of Saline-alkali Stress on Ion Absorption and Distribution of Camphor Seedling

以2年生香樟幼苗为材料,采用不同浓度Na HCO_3和Na_2CO_3(1︰1)混合溶液(0、50、100、200、300 mmol/L)处理,研究香樟幼苗对Fe^(2+)、Mg^(2+)、K^+、Na^+的吸收和分配。结果表明:随盐碱胁迫程度的增加,香樟幼苗根系和茎器官中的K^+含量呈下降趋势,而叶片中的K^+含量呈逐步上升趋势,其中叶片中的K^+含量最高,其次是根系,茎器官中的K^+含量最低;香樟幼苗根系、茎、叶片中的Na^+含量呈逐步上升趋势,其中根系中的Na^+含量最高,其次是叶片,茎器官中的Na^+含量最低;香樟幼苗根系、茎、叶片中的K^+/Na^+呈逐步下降趋势,其中茎器官中的K^+/Na^+最高,其次是叶片,根系中的K^+/Na^+最低。低盐碱胁迫(0~100 mmol/L)提高根、茎、叶器官中Fe^(2+)的含量,提高香樟叶片中叶绿素a、叶绿素b和总叶绿素的含量;而高盐碱胁迫(100~300 mmol/L)则降低根器官中Fe^(2+)的含量,增加茎、叶器官中Fe^(2+)的含量,明显降低叶绿素a、叶绿素b和总叶绿素的含量,根器官中Fe^(2+)的含量最高,其次是茎器官,叶器官中Fe^(2+)的含量最低。盐碱胁迫对香樟幼苗根、茎、叶器官中Mg^(2+)的含量影响差异不显著。盐碱胁迫初期,香樟幼苗通过将Na^+截留在根部,促进根器官对K^+、Fe^(2+)等营养元素的吸收和转运,提高自身对低盐碱胁迫(0~100 mmol/L)的耐受性;高盐碱胁迫(100~300 mmol/L)严重影响香樟幼苗对K^+、Fe^(2+)等营养元素的吸收和转运,影响香樟正常生长发育。

The biennial camphor seeding was used as test material and treated under different concentrations of NaHCO3 and NaECO3 to study the assimilations and distributions of Fe2＋, Mg2＋, K＋ and Na＋ by camphor seedling. The results showed that, with the increase of salinity-alkalinity stress degree, K＋ contents in roots and stems decreased but increased in leaves and K＋ content was highest in leaves, followed by in roots and in stems; Na＋ contents in roots, stems and leaves increased, and Na＋ content was highest in roots, followed by in leaves and in stems; K＋/Na＋ in roots, stems and leaves decreased, and K＋/Na＋ was highest in stems, followed by in leaves and in roots. Fe2＋ contents in stems, roots and leaves increased under low salinity stress （0-100mmol/L）, contents of chlorophyll a, b and total chlorophyll in leaves increased; Fe2＋ contents in roots, contents of chlorophyll a, b and total chlorophyll in leaves decreased significantly under high salinity stress （100-300 mmol/L）, Fe2＋ contents in stems and leaves increased. Fe2＋ content was highest in roots, followed by in stems and in leaves. The effects of salinity- alkalinity stress on the assimilation and distribution of Mg2＋ were not significant. The assimilation and distribution of Fe2＋ and K＋ in camphor seedlings is promoted by intercepting Na＋ in the roots in the early stage of salinity-alkalinity stress, and then improve the tolerance of low salinity-alkalinity stress （0-100 mmol/L）. The assimilation and distribution of Fe2＋ and K＋ in camphor seedlings are intensively inhibited under high salinity-alkalinity stress （100-300 mmol/L）, thus hinder the normal growth of camphor seedlings.