无机氮供应对甘蓝型油菜组培苗盐耐受能力的影响

Effect of inorganic nitrogen supply on the salt-tolerance of Brassica napus plantlets in vitro

关键词:  甘蓝型油菜组培苗,硝酸钠,盐胁迫,稳定碳同位素,自养能力

Key words:  Brassica napus plantlets, sodium nitrate, salt stress, stable carbon isotope, photosynthetic capacity

摘要:

该研究以甘蓝型油菜组培苗为材料,使用硝酸钠来提供唯一氮源和盐胁迫条件,测定甘蓝型油菜组培苗的生物量、叶绿素含量和叶片稳定碳同位素值,通过稳定碳同位素值评估甘蓝型油菜组培苗的自养能力,并基于自养能力研究甘蓝型油菜组培苗的无机氮供应与盐耐受能力的关系。结果表明:(1)供应40 mmol·L^-1硝态氮能消除轻度盐胁迫的不利影响,供应80 mmol·L^-1硝态氮能有效缓减中度盐胁迫的不利影响,但在重度盐胁迫条件下,即使供应过量的无机氮,甘蓝型油菜组培苗的生长仍然受到显著的抑制。(2)甘蓝型油菜组培苗的叶绿素含量随盐胁迫程度的增加而逐渐降低。(3)甘蓝型油菜组培苗的自养能力在轻度盐胁迫时达到最大, 但盐胁迫程度的加剧会显著降低甘蓝型油菜组培苗的自养能力。由此可知,当植物的无机氮需求得到满足后,自养能力的强弱将决定植物的盐耐受能力,而过量的无机氮供应不能提高重度盐胁迫条件下植物的自养能力。

Abstract:

The Brassica napus(Bn)plantlets in vitro were used as the experimental materials in this study. The sodium nitrate was employed to provide the sole nitrogen source and salt stress. The growth parameters, chlorophyll contents and foliar δ¹³C of B. napus plantlets were measured in this study. The photosynthetic capacity of B. napus plantlets was estimated by the stable carbon isotope value. The relationship between inorganic nitrogen supply and salt-tolerance of the B. napus plantlets was studied based on the photosynthetic capacity. The results were as follows:(1)The deleterious effect of slight salt stress could be counteracted by 40 mmol·L^-1 sodium nitrate, while the deleterious effect of moderate salt stress could be effectively relieved by 80 mmol·L^-1 sodium nitrate. However, even if the inorganic nitrogen supply was excessive, the growth of B. napus plantlets was heavily inhibited by the severe salt stress.(2)The chlorophyll contents of B. napus plantlets decreased gradually with increasing salt stress.(3)The photosynthetic capacity of B. napus plantlets reached the maximum under slight salt stress condition. However, the photosynthetic capacity of B. napus plantlets decreased obviously with increasing salt stress. Hence, when the inorganic nitrogen demand is met for plants, the salt-tolerance of plants will depend on the photosynthetic capacity. Excessive inorganic nitrogen supply can not improve the photosynthetic capacity of plants suffered from the severe salt stress.