[Effects of applying selenium on selenium allocation, grain yield, and grain quality of two maize cultivars].

A pot experiment with conventional maize cultivar ZD958 and glutinous maize cultivar JN218 was conducted to study the effects of applying different concentrations (0, 10, 25 and 50 mg x kg(-1)) of selenium (Se) on the Se allocation in plant organs, grain yield, and its quality. At low concentrations (< or = 10 mg x kg(-1)), Se stimulated maize growth, and increased biomass accumulation and grain yield significantly. At high concentrations (> 25 mg x kg(-1)), Se inhibited maize growth, and decreased dry mass accumulation, grain yield, and its quality. The Se concentration in plant organs was in the order of root > leaf > stalk > sheath. The Se concentrations in plant organs had a positive correlation with the Se concentration in soil. Comparing with ZD958, JN218 could accumulate more Se in natural low-Se environment, but enrich lesser Se in the environment with 10 mg x kg(-1) of Se. Taking the Se accumulation amount in grain and aboveground vegetative organs as the standard for evaluation, JN218 was more available planted on natural low-Se (0.25 mg x kg(-1)) soil or high-Se (25 mg x kg(-1)) soil, while ZD958 was appropriate planted on Se-rich (10 mg x kg(-1)) soil or Se-polluted (50 mg x kg(-1)) soil.

[Effects of arsenic on maize growth, antioxidant system, and ion distribution].

A greenhouse sand culture experiment was conducted to study the effects of arsenic (As) on the biomass accumulation, photosynthetic pigments, antioxidant system, and the absorption and distribution of As and mineral ions in maize Zhengdan 958. At lower concentrations (<2 mg As x L(-1)), As stimulated the growth of maize seedlings, and increased the plant height, taproot length, and biomass accumulation significantly; at higher concentrations (>4 mg As x L(-1)), As inhibited the seedlings growth severely. At 2 mg As x L(-1), the chlorophyll a, b, and a+b contents reached their peaks; but with increasing As concentration, the chlorophyll contents decreased gradually. At 10 mg As x L(-1), the destruction of chloroplast structure and the dissolution of thylakoid membrane were observed by electron microscopy. With increasing As concentration, the activities of antioxidant enzymes SOD, POD, and CAT in root increased, and those in leaf reached the maximum at 8 mg As x L(-1). The sensibility of the enzymes in leaf to As stress was in the order of POD >CAT>SOD. Correlation analysis showed that the contents of MDA, soluble sugar, and soluble protein were positively correlated with As concentration. High concentration As inhibited the absorption of P, K, Ca, Fe and other elements obviously. And comparing with shoot, root was more sensitive to As stress. The growth indices of root could be more available to be used as the indicators of plant arsenic toxicity.