硒的价态与浓度对香橙幼苗生长和AsA-GSH循环的影响

以盆栽香橙为试材,分析不同施用浓度Se⁶⁺和Se⁴⁺对植株生长和抗坏血酸(AsA) -谷胱甘肽(GSH)循环的影响.结果表明: 两种价态硒均可促进香橙生长,主要表现在增加了叶面积、株高、鲜质量和干质量.施用Se⁶⁺显著提高了香橙硒含量,且硒主要分配在叶片;而施用Se⁴⁺虽能提高硒含量,但其含量远低于Se⁶⁺处理,且主要分配在根系.施硒提高了叶片叶绿素和过氧化氢(H₂O₂)含量,且Se⁶⁺处理高于Se⁴⁺处理.Se⁶⁺浓度≤2.0 mg·L^-1处理能提高谷胱甘肽还原酶(GR)与谷胱甘肽过氧化物酶(GPX)活性、GSH与氧化型谷胱甘肽(GSSG)量,Se⁶⁺浓度≥4.0 mg·L^-1处理降低GSH循环的物质和酶活性;而Se⁴⁺浓度≤ 2.0 mg·L^-1处理能提高脱氢抗坏血酸还原酶(DHAR)与抗坏血酸过氧化物酶(APX)活性,且具有较高的AsA/AsA+脱氢抗坏血酸(DHA)]比值,Se⁴⁺浓度≥4.0 mg·L^-1 处理的GSH循环的物质和酶活性升高.综上,硒的不同价态和施用浓度对AsA-GSH循环相关物质含量和酶活性的影响不同.结合香橙生长指标和抗氧化水平,Se⁶⁺和Se⁴⁺的适宜浓度分别为2.0和4.0 mg·L^-1.

Effects of selenium valence states and application concentrations on plant growth,ascorbate-glutathione cycle in Citrus junos cv. Ziyang Xiangcheng

Potted Citrus. junos cv. Ziyang Xiangcheng seedlings were used to study the effects of selenium (Se) valence states (Se⁶⁺ and Se⁴⁺) on plant growth and antioxidants and antixodases in ascorbate(AsA)-glutathione (GSH) cycle. The results showed that Se⁶⁺ and Se⁴⁺ (from 1.0 mg·L^-1 to 8.0 mg·L^-1) stimulated the seedling growth by increasing plant height, leaf areas, and fresh or dry mass. Applying Se⁶⁺significantly increased plant Se levels mainly in leaf, and applying Se⁴⁺ slightly increased Se content mainly in root. Certain valence states and concentrations of Se increased leaf chlorophyll and hydrogen peroxide (H₂O₂) content. Se⁶⁺≤2.0 mg·L^-1 treatments enhanced the activates of glutathione reductase (GR) and glutathione peroxidase (GPX), and the contents of GSH and oxidized glutathione (GSSG), while Se⁶⁺≥4.0 mg·L^-1 treatments reduced the antioxidant contents and antixodase activities of GSH cycle. Moreover, Se⁴⁺≤ 2.0 mg·L^-1 treatments increased the activities of dehydroascorbate reductase (DHAR) and ascorbate peroxidase (APX), and resulted in higher AsA/AsA+dehydroascorbic acid (DHA)] ratio. When Se⁴⁺≥4.0 mg·L ^-1, the antioxidant contents and antixodase activities of GSH cycle were increased. Together, this study showed that different valence states and application concentrations of Se showed different influences on AsA-GSH cycle in citrus, and 2.0 mg·L^-1 Se⁶⁺ and 4.0 mg·L^-1 Se⁴⁺ were the best concentrations for plant growth.