Abstract: Here we conducted an indoor pot experiment to investigate the effects and duration of action of brassinolide (BR) on the photosynthetic capacity of Leymus secalinus leaves. In the experiment, different concentrations of BR (0, 0.05, 0.1, 0.15, 0.2 μmol·L^-1) were sprayed on the foliage, and the photosynthesis-related indexes were measured after 7, 14 and 21 d, respectively. The results showed that BR treatments significantly increased the chlorophyll content, net photosynthetic rate, stomatal conductivity, transpiration rate, maximum photochemical quantum yield of PSII, actual photochemical quantum yield of PSII，photochemical quenching coefficient and soluble sugar in Leymus secalinus leaves, and significantly reduced Intercellular CO₂ concentration, non-photochemical quenching coefficient. Different concentrations of BR affected the photosynthetic capacity of Leymus secalinus for different durations, the duration of the effect of 0.05 μmol·L^-1 BR treatment was 7 d, the duration of the effect of 0.1 μmol·L^-1 BR treatment was 14 d, and the duration of the effect of spraying 0.15 and 0.2 μmol·L^-1 BR treatments was 21 d. Therefore, in the actual production of Leymus secalinus, the photosynthetic capacity of Leymus secalinus can be effectively enhanced by foliar spraying of 0.15 μmol·L^-1 BR thereby accumulating more photosynthetic products, with an action cycle of about 21 d.

Key words: Leymus secalinus, Brassinolide, Chlorophyll, Photosynthetic characteristics, Fluorescence characteristics

摘要： 为探究油菜素内酯(Brassinolide，BR)对赖草(Leymus secalinus)叶片光合能力的影响及作用时间,采用室内盆栽试验，叶面喷施不同浓度(0，0.05，0.1，0.15，0.2 μmol·L^-1)的BR，在 7，14，21 d后分别测定光合相关指标。结果表明，BR处理可以显著提高赖草叶片的叶绿素含量、净光合速率、气孔导度、蒸腾速率、PSⅡ最大光化学量子产量、PSⅡ实际光量子产量、光化学淬灭系数、可溶性糖含量，显著降低了胞间CO₂浓度、非光化学淬灭系数。不同浓度BR影响赖草光合能力的作用时间不同，0.05 μmol·L^-1BR处理的作用时间为7 d，0.1 μmol·L^-1BR处理作用时间为14 d，喷施0.15和0.2 μmol·L^-1BR处理下的持续时间为21 d。因此，在赖草实际生产中，通过叶面喷施0.15 μmol·L^-1BR可以有效提升赖草的光合能力从而积累更多的光合产物，其作用周期在21 d左右。

关键词: 赖草, 油菜素内酯, 叶绿素, 光合特性, 荧光参数