为了揭示干旱胁迫下外源油菜素内酯对玉米幼苗光合作用的保护机制,采用溶液培养的方法,以驻玉309为试验材料,研究外源油菜素内酯(BR)预处理及20% PEG-6000模拟干旱胁迫后玉米幼苗的生长参数、叶绿素含量、光合参数、叶绿素荧光参数及D1蛋白含量的变化.结果表明,与干旱胁迫处理(PEG)相比,BR+PEG处理的玉米苗株高增加45.87%,根长增加20.56%,总干物质积累增加8.01%,叶片相对含水量提高4.50%,叶绿素a含量增加26.32%,光合参数(Pn、Gs、Ci、Tr)分别提高9.57%,38.23%,30.19%,28.12%,光合系统Ⅱ(ΦPSⅡ)活性提高了20.48%,最大光化学效率提高了0.66%,光合系统Ⅱ绝对电子传递速率(ETR(Ⅱ)和相对电子传递速率rETR(Ⅱ))分别提高20.40%和31.02%;D1蛋白含量增加37.34%(P<0.05).说明在干旱胁迫条件下叶片喷施BR可以改善玉米幼苗的生长发育,减缓光合系统的损伤,促进D1蛋白质的稳定,从而提高玉米幼苗对干旱胁迫的适应性.%In order to reveal the protective mechanism of exogenous Brassinolide on the photosynthesis of maize seedlings under drought stress,this experiment used the Zhuyu 309 as test materials and adopted the solution culture method,studying the changes of growth parameters,chlorophyll content,photosynthetic parameters,chlorophyll fluorescence parameters and D1 protein content of maize seedlings that used 20% PEG-6000 to simulate drought stress after exogenous Brassinolide (BR) pretreatment.Compared with that of drought stress,the results of corn seedling which after the BR pretreatment showed that its height increased by 45.87%,the root length increased by 20.56%,the total dry matter accumulation increased by 8.01%,the relative water content increased by 4.50%,chlorophyll a content increased by 26.32%,and photosynthetic parameters (Pn,Gs,Ci,Tr) increased by 9.57%,38.23%,30.19% and 28.12% respectively,the activity of photosynthetic system Ⅱ (ΦPSⅡ) increased by 20.48%,and the maximum photochemical efficiency increased by 0.66%.Photosynthetic system Ⅱ absolute electron transport rate (ETR (Ⅱ) and the relative electron transport rate of photosynthetic system Ⅱ(rETR(Ⅱ)) were increased by 20.40% and 31.02% respectively.The content of D1 protein increased by 37.34% (P<0.05).The results showed that BR treatment under drought stress condition could improve the growth and development of maize seedlings,alleviate the damage of photosynthesis system,promote the stability of D1 protein and improve the adaptability of maize seedling to drought stress.
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