干旱胁迫对玉米叶片光合特性和穗发育特征的影响

玉米是需水量较大的粮食作物之一,拔节至开花的穗期是其一生中的需水临界期,研究玉米穗期对干旱胁迫的响应机制对提高玉米干旱适应性具有重要意义。以筛选后的干旱敏感自交系PH6WC(6WC)和抗旱自交系郑58(Z58)为试验材料,采用测坑控水试验,于穗期设置3个水分处理(正常灌水CK、轻度干旱LD、中度干旱MD),研究了穗期不同水分处理对雌雄穗发育特性、开花吐丝间隔以及穗位叶光合特性的影响。结果表明:LD对Z58的株高、雄穗生长特性、叶绿素相对含量和光系统II最大光化学效率没有显著影响,但雌穗长显著降低;MD显著降低了Z58的穗位叶光合特性、雌雄穗的穗长和干物质积累。对于6WC,LD抑制了其植株生长和穗的发育,使雌穗长、雌穗直径、雄穗长、干物质向穗的分配比率、穗位叶的叶绿素a、叶绿素b和光合性能综合指数(PIABS)分别降低了35.3%、11.8%、20.6%、25%、21.1%、20%、23.8%;干旱胁迫程度越重对6WC雌雄穗的发育影响越大。此外,LD与MD分别延长6WC的开花吐丝间隔期(ASI)至5天、9天,LD和MD分别延长Z58的ASI 0、3天。综上所述:穗期的干旱胁迫在不同程度上影响了6WC和Z58穗位叶的光合特性,但是对干旱敏感自交系6WC雌雄穗的生长发育的抑制显著高于Z58,以至于降低了干物质向穗部的积累与分配。

Effects of drought on photosynthesis and ear development characteristics of maize

Maize is one of the grain crops with a large demand of water. Its ear period from jointing stage to anthesis stage is the critical period of its life. It is significant meaningful to study the response mechanism of ear stage to drought stress for improving drought adaptability of maize. In this paper, drought sensitive inbred line PH6WC (6WC) and drought-resistant inbred line Zheng 58 (Z58) were selected as experimental materials. Water control experiment was performed in the pit, and three water treatments (normal irrigation CK, mild drought LD, and moderate drought MD) were set up at ear period, drought treatment would recover to the normal water level after anthesis stage. The ear and tassel development characteristics, anthesis-silking interval (ASI), and the influence of ear leaf photosynthetic characteristics were measured under different water treatments. The results showed that LD didn''t significantly affect plant height, growth characteristics of ear, relative content of chlorophyll, and maximum photochemical efficiency of PSII in Z58, but significantly decreased the length of ear. MD significantly reduced photosynthetic characteristics, ear length and dry matter accumulation of both ear and tassel in Z58. As for 6WC, LD inhibited the growth of plant and the development of ear, reduced the length and diameter of ear, length of tassel, distribution ratio of dry matter to ear, the content of chlorophyll a and b, and composite index of photosynthetic performance (PI_ABS) by 35.3%, 11.8%, 20.6%, 25.0%, 21.1%, 20.0% and 23.8%, respectively. The higher the degree of drought stress was, the greater the influence on the development of 6WC ear was. In addition, LD and MD resulted in 5 and 9 days'' delay in ASI of 6WC, respectively; LD and MD resulted in 0 and 3 days'' delay in ASI of Z58, respectively. To sum up, the drought stress at ear stage affected the photosynthesis characteristics of 6WC and Z58 to different degrees, furtherly the growth and development of ear and tassel of the drought sensitive inbred line was inhibited significantly more than that of the drought-resistant inbred line, which reduced the accumulation and distribution of dry matter to ear.