不同价态外源硒对小白菜生长及养分吸收的影响

采用土壤外源加入两种不同价态的硒 [Se(Ⅳ)和 Se(Ⅵ)]的盆栽试验，研究了其对小白菜生长、营养元素和硒吸收的影响。结果表明，施硒对小白菜的生长均表现出低浓度(5 mg/kg)促进，高浓度(5 mg/kg)抑制趋势。Se(Ⅵ)处理小白菜地上部硒含量大于地下部；而Se(Ⅳ)处理则与Se(Ⅵ)相反。硒从根部转运到地上部的转移因子Se(Ⅵ)处理大于Se(Ⅳ)。两种价态硒处理，小白菜对氮、磷、钾、硫、镁和锌的吸收也表现出低浓度时为促进作用，高浓度为抑制作用。Se(Ⅵ)显著增加了钙的吸收，Se(Ⅳ)却无显著影响；Se(Ⅳ)和Se(Ⅵ)均能促进小白菜对铁的吸收。相同浓度下， Se(Ⅵ)对各个营养元素吸收的影响显著大于Se(Ⅳ)。综合硒对生长和养分吸收的影响看出，小白菜施硒量以Se(Ⅵ)不超过2.5 mg/kg或Se(Ⅳ)不超过5 mg/kg为宜。

Effects of selenite and selenate on growth and nutrient absorption of pakchoi

 A pot experiment applied with exogenous selenium [Se (Ⅳ) and Se (Ⅵ)] were carried out to study effects of selenite and selenate on the growth and nutrient absorption of pakchoi (Brassica chinensis), and to provide theoretical basis for the development prospect of selenium deficiency crops and the Plant-based Bioremediation. The results indicate that application of the selenium promotes the growth index and biomass of pakchoi under the low concentration and suppresses those under the high concentration. The adsorption of Se (Ⅵ) of the shoots of pakchoi is larger and faster than that of the roots. For the treatment of Se(Ⅳ), the ratio of adsorption in the shoots and roots are opposite. The cumulated capacities of other nutrients of pakchoi are different under the Se treatments. First, application of the selenium promotes the absorptions of N, P, K, S, Mg and Zn of pakchoi under the low concentration and suppresses those under the high concentration. Application of the Se(Ⅵ) promotes the absorption of Ca significantly, while the effect of Se(Ⅳ) is not significant. Applications of the Se(Ⅵ) and Se(Ⅳ) both promotes the absorption of Fe of pakchoi. The effects of different extraneous selenium on the adsorption of the nutrient elements are significant, and the effect of Se(Ⅵ) is significantly larger than that of Se(Ⅳ). Comprehensive analysis of selenium on the pakchoi, it is appropriate that the soil Se does not exceed 2.5 mg/kg (Se (Ⅵ)) or 5 mg/kg (Se (Ⅳ).