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【目的】探明油菜素内酯(brassinolide,BR)对阔世玛胁迫下谷子叶片的光合荧光特性及糖代谢的影响,为谷子田磺酰脲类除草剂阔世玛的安全应用及利用植物生长调节剂油菜素内酯缓解除草剂药害提供理论基础和技术途径。【方法】采用完全随机设计,重复3次,以杂交高产谷张杂5号和普通优质谷晋谷21号为材料,进行盆栽试验,待幼苗长至3—5叶期时,喷施7.5 mg·L~(-1)阔世玛,药后1 d,分别叶面喷施清水(对照)、0.05、0.1、0.2和0.4 mg·L~(-1)的油菜素内酯,7 d后对所有处理的谷子幼苗株高、叶面积、鲜重等农艺性状、叶片光合色素含量、气体交换参数、叶绿素荧光参数、糖含量及蔗糖代谢关键酶活性进行测定与分析。【结果】在7.5 mg·L~(-1)阔世玛胁迫下,谷子的株高、叶面积、鲜重、叶绿素a、叶绿素b、类胡萝卜素、叶绿素(a+b)、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、最大光化学产量(Fv/Fm)、表观光合电子传递速率(ETR)、非调节性能量耗散量子产量(Y(NO))、中性转化酶(NI)、蔗糖合成酶(SS)及蔗糖磷酸合成酶(SPS)活性显著降低;而胞间CO2浓度(Ci)、调节性能量耗散量子产量(Y(NPQ))、还原性糖、蔗糖和淀粉含量显著升高。药后1 d喷施适宜浓度的BR能部分缓解阔世玛对谷子的药害,显著提高谷子的株高、叶面积、鲜重、光合色素含量、Pn、Tr、Gs、Fv/Fm、ETR、Y(NO)、NI、SS及SPS活性,并显著降低Ci、Y(NPQ)、还原性糖、蔗糖和淀粉含量;其中,0.05—0.1 mg·L~(-1) BR对缓解张杂5号阔世玛药害的效果较好,0.1—0.2 mg·L~(-1) BR对缓解晋谷21号阔世玛药害的效果较好。≥0.4 mg·L~(-1) BR不能缓解阔世玛药害。【结论】7.5 mg·L~(-1)的阔世玛对谷子产生显著药害的原因之一是降低了其光合色素含量,抑制了PSⅡ光化学活性,影响了糖代谢的正常运转。0.1 mg·L~(-1)的油菜素内酯通过提高光合色素含量、增加气孔导度、提高PSⅡ光化学活性、促进碳水化合物的卸出、维持蔗糖代谢平衡等来缓解阔世玛对谷子光合作用的抑制。
【Objective】 The objective of this study was to investigate the effects of brassinolide (BR) on the photosynthetic characteristics and sugar metabolism of millet leaves under millergrass stress. Growth regulator brassinosteroids to alleviate the phytotoxicity provide theoretical basis and technical approach. 【Method】 The pot experiment was conducted in a completely randomized design and repeated three times with the hybridization of high yield Guzhang 5 and high quality GuJing 21 as the materials. When the seedlings grew to 3-5 leaf stage, 7.5 mg · L ~ (-1) koramar was sprayed with water (control), 0.05,0.1,0.2 and 0.4 mg · L -1 brassinolide on the foliar surface after 1 d after treatment, respectively. After 7 days The plant height, leaf area, fresh weight and other agronomic traits, leaf photosynthetic pigment content, gas exchange parameters, chlorophyll fluorescence parameters, sugar content and key enzyme activities of sucrose metabolism were measured and analyzed. 【Result】 The results showed that plant height, leaf area, fresh weight, chlorophyll a, chlorophyll b, carotenoid, chlorophyll (a + b) and net photosynthetic rate of millet under the stress of 7.5 mg · L ~ (-1) Pn, Tr, Gs, Fv / Fm, ETR, and Y (NO) While the activities of NI, SS and SPS were significantly decreased, while the intercellular CO2 concentration (Ci), regulatory energy dissipation quantum yield (Y (NPQ)), Reducing sugar, sucrose and starch content was significantly increased. Spraying appropriate concentration of BR on the 1st day after treatment could relieve the phytotoxicity of Quantum to millet and significantly increase the plant height, leaf area, fresh weight, photosynthetic pigment content, Pn, Tr, Gs, Fv / Fm, ETR (NPQ), reducing sugar, sucrose and starch content were significantly decreased in the groups with 0.05-0.1 mg · L -1 BR, 5 had a better effect on phytotoxicity, and 0.1-0.2 mg · L -1 BR had a good effect on alleviating phytoplankton injury of Jin Gu 21. ≥0.4 mg · L -1 BR can not relieve phytase injury. 【Conclusion】 One of the reasons for the significant phytotoxicity to millet at 7.5 mg · L -1 is that the photosynthetic pigment content is reduced, the photochemical activity of PS Ⅱ is inhibited, and the normal operation of sugar metabolism is affected. Brassinolide at 0.1 mg · L -1 could alleviate photosynthesis and photosynthetic rate of photosynthesis of Magnaporthe giganteum by increasing photosynthetic pigment content, increasing stomatal conductance, enhancing photochemical activity of PSⅡ, promoting the unloading of carbohydrates and maintaining the balance of sucrose metabolism Inhibition of effects.