海藻多糖–纳米硒的结构及其促进水稻硒累积的机理

【目的】以海藻提取物和亚硒酸钠为原料，采用抗坏血酸还原法制备了海藻多糖–纳米硒(APS-SeNPs)，以期为富硒大米生产提供高效的富硒肥料。【方法】采用单因素试验和响应面法优化APS-SeNPs的制备工艺；借助傅里叶红外光谱、透射电镜和表面张力仪对APS-SeNPs进行表征。通过开展大田试验，探究0、5、25mg/L APS-SeNPs叶面喷施对粳稻‘洛稻998’和籼稻‘川香优2号’硒累积的影响。【结果】1) APS-SeNPs的最佳制备工艺:硒添加量2800 mg/L，亚硒酸钠与抗坏血酸的摩尔比19∶100，反应温度32℃，时间20 min。APSSeNPs粒径为38.94 nm,Zeta电位为–52.17 mV。红外分析结果表明，海藻多糖与纳米硒形成了新的Se—O化学键。APS-SeNPs的表面张力为46.23 mN/m，显著低于Na₂SeO₃。APS-SeNPs在水稻叶片上的持液量为6.28mg/cm²，而Na₂SeO₃只有3.94 mg/cm²。2...

Structure of alginate polysaccharide selenium-nanoparticles and the mechanism of promoting selenium accumulation in rice

  【Objectives】  The structure of alginate polysaccharide selenium-nanoparticles (APS-SeNPS) was characterized for explaining its efficiency in promoting Se absorption in rice. The optimum foliar spraying time and content of APS-SeNPS were studied for its efficient application.   【Methods】  The preparation process of APS-SeNPs was optimized by a single-factor experiment and response-surface methodology. Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and surface tensiometer were used to characterize the APS-SeNPs. A field foliar spraying experiment was conducted on rice, with APS-SeNPs concentration of 0, 5 or 25 mg/L, respectively. Se accumulation in japonica rice ‘Luodao 998’ and indica rice ‘Chuanxiangyou 2’ were investigated.   【Results】  1) The optimized preparation conditions of APS-SeNPs containing Se 2800 mg/L were as follows: molar ratio of Na₂SeO₃ to ascorbic acid (Se∶Vc) was 19∶100, reaction temperature 32℃ and reaction time 20 min. The produced particle size of APS-SeNPs was 38.94 nm, and the Zeta potential was ?52.17 mV. The Se—O chemical bond was identified in APS-SeNPs by FTIR. The surface tension of APS-SeNPs is 46.23 mN/m, which is significantly lower than that of Na₂SeO₃. The liquid holding capacity of APS-SeNPs on rice leaves was 6.28 mg/cm2, which was much higher than that of Na₂SeO₃ (3.94 mg/cm2). 2) Field experiments revealed that Se contents in each organs of the two rice cultivars increased with the increase of spraying Se concentration. The Se content in both the rice cultivars was in order of leaf>rice husk>brown rice. The Se content of brown rice in APS-SeNPs treatment was 2.2%?34.5% higher than that in Na₂SeO₃ treatments. The organic Se proportion in brown rice treated with two Se sources was 70.9% to 85.3%, and the organic Se proportion in brown rice was decreased with the increase of Se spray concentrations, but the organic Se proportion in brown rice treated with APS-SeNPs was 2.1?7.6 percentage points higher than that treated with Na₂SeO₃.   【Conclusions】  In the APS-SeNPs structure, Se—O bond was formed, which decreased the surface tension and lead to higher liquid holding capacity of APS-SeNPs on leaves, which was good for the absorption of Se. Therefore, the accumulation of Se in grain and the proportion of organic Se in grain were increased. Spraying 5 mg/L APS-SeNPs at grain filling stage of rice increases the brown rice Se content to the enrichment standard (0.04?0.3 mg/kg).