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【目的】明确油菜素内酯(BR)对玉米光合特性的影响及作用机制,为油菜素内酯在玉米田的高效利用提供理论依据和技术参考。【方法】于玉米8叶期喷施100 nmol·L~(-1) BR,对其叶片进行叶绿体结构、淀粉粒积累、叶绿素含量、PEPC活性、光合速率、蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)活性的检测与分析。【结果】油菜素内酯处理8叶期玉米15 d后,与对照相比,玉米叶片的净光合速率提高了32.6%,同时,叶绿体中淀粉粒的积累明显变多变大,叶绿素含量高出对照28.57%,以上结果说明BR处理可提高玉米叶片的捕光能力;PEPC是C4植物中催化PEP固定CO_2的酶,本研究结果表明BR处理可提高玉米叶片中PEPC的活性,与对照相比,其活性提高了14.52%,这说明BR处理可提高玉米叶片固定CO_2的能力;光合产物运输是决定产量的重要因素,通过对玉米叶片疏导组织细胞的超微观察,发现BR处理后韧皮部输导组织的细胞内含物增加;蔗糖是光合产物的主要运输形式,蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)是蔗糖合成的关键酶,其活性可反映同化物向籽粒运输能力和强度,本研究发现BR处理后SS和SPS的活性分别提高了28.26%和30.20%,上述结果说明BR处理可提高玉米光合产物的输出能力。【结论】油菜素内酯通过提高光合色素含量来提高玉米叶片的光能利用率;通过提高PEP羧化酶活性提高玉米叶片固定CO_2的能力;通过提高蔗糖合成酶和蔗糖磷酸酶活性,促进玉米叶片光作用产生的有机物的运输和分配。
【Objective】 The purpose of this study was to determine the effects of brassinolide (BR) on photosynthetic characteristics of maize and to provide a theoretical basis and technical reference for the efficient use of brassinolide in maize field. 【Method】 Chloroplast structure, starch grains accumulation, chlorophyll content, PEPC activity, photosynthetic rate, sucrose phosphate synthase (SPS) and sucrose content of leaves were sprayed on 100 nmol·L -1 BR at 8 leaf stages of maize. Detection and Analysis of Synthase (SS) Activity. 【Result】 The net photosynthetic rate of maize leaves increased by 32.6% compared with the control after 15 days of treatment with brassinolide. At the same time, the accumulation of starch granules in chloroplasts obviously increased and the chlorophyll content was higher Compared with 28.57%, the above results show that BR treatment can improve the light harvesting ability of maize leaves; PEPC is the enzyme that catalyzes the PEP immobilization of CO_2 in C4 plants, and the results show that BR treatment can improve the activity of PEPC in maize leaves. Compared with the control, The activity of BR was increased by 14.52%, which indicated that BR treatment could increase the ability of corn leaves to fix CO_2. The photosynthetic transport was an important factor in yield control. Through the ultrastructure observation of maize leaves, Sucrose synthase (SS) and sucrose phosphate synthase (SPS) are the key enzymes in the synthesis of sucrose. Its activity can reflect the transport ability and intensity of assimilates to grain, The results showed that the activity of SS and SPS increased by 28.26% and 30.20% after BR treatment, respectively. These results indicated that BR treatment could increase the output ability of maize photosynthate. 【Conclusion】 Brassinolone enhanced photosynthetic pigment utilization in maize leaves by increasing photosynthetic pigment content. The ability of corn leaf to fix CO 2 was enhanced by increasing PEP carboxylase activity. Maize was promoted by increasing sucrose synthase and sucrose phosphatase activity Transport and distribution of organic matter resulting from the action of light on leaves.