玉米种子萌发过程中Na+、K+和Ca2+含量变化与耐盐性的关系

玉米耐盐品种登海9号和盐敏感品种浚单18在含0、50、100、150和200 mmol L^-1 NaCl的营养液中萌发生长, 采用等离子质谱分别测定其萌动种子种皮、胚、胚乳和幼苗根、根颈、叶中Na⁺、K⁺、Ca²⁺的含量。结果表明, 随着培养液中NaCl浓度的增加, 玉米体内Na⁺含量逐渐升高, 在幼苗中表现地下部(根和根颈)显著高于地上部(叶); 在萌动种子中, 胚中Na⁺积累量显著高于种皮和胚乳。根系积累Na⁺能力较强, 胚拒Na⁺能力较弱, 种皮具有一定的Na⁺累积能力。随NaCl浓度的增加, K⁺和Ca²⁺含量逐渐降低, 尤其是Ca²⁺含量急剧减少, 达38.4%~55.9%(登海9号)和65.6%~78.2%(浚单18)。玉米根、根颈、种皮的Na⁺积累能力、叶的拒Na+能力和幼苗选择吸收Ca²⁺的能力可能与品种耐盐性有关。

Relationship between Changes of Na+,K+,and Ca2+ Contents during Seed Germination and Salt Tolerance in Maize

Maize (Zea mays L.) seeds of a salt tolerant cultivar Denghai 9 and a salt sensitive cultivar Jundan 18 were germinated and grown in 1/4 and 1/2 Hoagland solutions with 0, 50, 100, 150, and 200 mmol L^-1 NaCl, respectively. The contents of Na⁺, K⁺, and Ca²⁺ in testa, embryo, endosperm, roots, root crown, and leaf were measured by ICP Mass. The Na⁺ content increased accordantly with the NaCl concentration in culture solution. In young seedlings, Na⁺ content in root and root crown was higher than that in leaf; in germinating seeds, it was significantly higher in embryo than in testa and endosperm. The capacity of Na⁺ accumulation in roots was strong, while the capacity of Na⁺ rejection in embryo was weak. The testa could also accumulate some Na⁺. The K⁺ and Ca²⁺ contents in germinating seeds and young seedlings of maize decreased obviously under NaCl stress, and the Ca²⁺ content showed changes in a large scale, which was 38.4%–55.9% in Denghai 9 and 65.6%–78.2% in Jundan 18. The capacities of Na⁺ accumulation and rejection as well as the Ca²⁺ selective absorption might be related to salt-tolerance of maize cultivars