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 tranfer factor of selenium in Se(Ⅵ) treatment is higher than that in Se(Ⅳ) treatment.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 promote 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 shows that the soil Se application rate beyond 2.5 mg/kg Se(Ⅵ) or 5 mg/kg Se(Ⅳ) is appropriate.