摘要:探讨不同基因型玉米叶片光合荧光特性、授粉结实能力及产量构成对花期高温胁迫及恢复的响应, 以期为未来气候变暖条件下夏玉米稳产高产提供理论依据。采用人工模拟增温试验, 选取2个耐热型玉米品种(‘浚单20’和‘郑单958’)和2个热敏感型玉米品种(‘先玉335’和‘农华101’)为试验材料, 设置花期高温胁迫和大田常温对照2个处理, 研究花期高温胁迫及恢复对不同耐热性玉米叶片光合荧光特性、授粉结实能力、干物质积累与分配和产量构成的影响。结果表明, 花期高温胁迫显著降低了玉米穗粒数, 增加了空秆率, 进而导致籽粒产量显著下降, 且耐热型品种产量下降幅度小于热敏感型品种。与对照相比, 花期高温胁迫下耐热型和热敏感型品种穗粒数分别降低22.25%和67.18%, 百粒重分别降低2.03%和5.00%, 空秆率分别增加206.37%和283.00%, 籽粒产量分别降低31.84%和67.33%, 其中穗粒数、空秆率和籽粒产量差异均达显著水平(P<0.05)。花期高温胁迫使得4个玉米品种有效绿叶面积和叶绿素含量降低, 光系统Ⅱ受损, 光合性能显著下降; 高温胁迫结束后, 光系统Ⅱ部分参数有所恢复, 叶绿素含量和净光合速率恢复至对照水平。花期高温胁迫对雌穗总小花数、雄穗总小花数和雄穗分枝数影响较小, 但使得散粉持续期缩短, 开花吐丝间隔期拉长, 造成雌雄不遇, 结实率显著降低。花期高温导致的授粉持续期缩短是结实率降低的主要原因。花期高温胁迫显著降低了4个玉米品种干物质积累量和干物质向穗(粒)的分配比例; 高温胁迫后, 耐热型和热敏感型品种成熟期的单株干物质量分别降低16.40%和25.73%, 籽粒干物质分配比率分别降低7.08%和46.80%, 差异均达显著水平(P<0.05)。花期高温胁迫导致玉米光合性能下降, 雌雄穗协调发育受到抑制, 干物质积累量显著减少, 使得结实率下降, 穗粒数减少, 籽粒产量显著降低。花期高温胁迫对热敏感型品种的产量形成、光合荧光特性、雌雄穗发育和干物质积累与分配的影响均高于耐热型品种。
关键词:玉米/
花期高温/
光合荧光特性/
授粉结实/
籽粒产量
Abstract:High temperatures during the flowering stage are likely to have a significant negative impact on maize growth and development, which is one of the most important factors affecting maize high and stable yield. This study aimed to evaluate the response of photosynthetic fluorescence characteristics, pollination, and yield components of different maize cultivars to high temperatures during the flowering stage to provide a theoretical basis for the stable and high yield of summer maize production under climate warming in the future. This study used heat-resistant maize cultivars, ‘XD20’ and ‘ZD958’, and heat-sensitive maize cultivars, ‘XY335’ and ‘NH101’, as research materials in a greenhouse. Then the influence of high temperature during the flowering stage (from 7 d before silking to 7 d after silking) on grain yield, leaf photosynthetic fluorescence characteristics, pollination, dry matter mass were investigated. High temperature during flowering significantly reduced the kernel number per ear and significantly increased the blank stem rate of different summer maize cultivars, leading to a significant decrease in grain yield. The grain yield decline of heat-resistant cultivars was less than that of heat-sensitive cultivars. Compared with the control, the kernel number per ear of the heat-resistant and heat-sensitive cultivars under high temperature significantly decreased by 22.25% and 67.18%, respectively, the 100-grain weight decreased by 2.03% and 5.00%, the blank stem rate significantly increased by 206.37% and 283.00%, and the grain yield significantly decreased by 31.84% and 67.33%, respectively. High temperature during flowering reduced effective green leaf area and chlorophyll content, impaired photosystem II, and significantly decreased the photosynthetic performance of the four maize cultivars. Under high-temperature stress, the leaf area of the heat-resistant and heat-sensitive cultivars decreased by 0.79% and 7.46%, the chlorophyll content decreased by 4.53% and 5.16%, the net photosynthetic rate (Pn) decreased by 19.9% and 31.6%, and the maximum photochemical efficiency (Fv/Fm) of PS Ⅱ decreased by 0.79% and 1.47%, respectively. After the high-temperature stress, some parameters of photosystem Ⅱ recovered, and chlorophyll content and Pn returned to the control level. High temperatures during flowering had little effect on the tassel branch number, tassel floret number, and ear filament number; but shortened the pollen shedding duration, lengthened the anthesis-silking interval, and significantly reduced the setting rate. Under high-temperature stress at the flowering stage, the tassel branch number of heat-resistant and heat-sensitive cultivars decreased by 4.76% and 13.66%, the tassel floret number decreased by 8.53% and 8.32%, the tear filament number decreased by 6.10% and 7.17%, the pollen shedding duration decreased by 10.81% and 26.94%, the anthesis-silking interval increased by 58.93% and 85.00%, the pollination duration decreased by 17.91% and 58.95%, and the kernel setting rate decreased by 14.77% and 63.10%, respectively. Shortening pollination duration was the main reason for the lower kernel setting rate. High temperature during flowering significantly reduced dry matter mass and the distribution ratio of dry matter to the ear or grain of four maize cultivars. After high-temperature stress, the dry matter mass per plant of heat-resistant and heat-sensitive cultivars decreased by 13.7% and 17.6%, and the distribution ratio of dry matter in the ear decreased by 49.16% and 56.51%, respectively; at maturity, the dry matter mass per plant decreased by 16.40% and 25.73%, and the distribution ratio of dry matter in the grain decreased by 7.08% and 46.80%, respectively. High temperature during flowering decreased the photosynthetic performance, inhibited the coordinated development of male and female panicles, and significantly reduced kernel setting rate, kernel number per ear, and grain yield. Compared with heat-sensitive cultivars, heat-resistant cultivars had higher photosynthetic capacity and pollination fruiting ability under high-temperature stress; their yield was less affected by high temperature.
Key words:Maize/
High temperature during flowering stage/
Photosynthetic fluorescence characteristics/
Pollination and fruitage/
Grain yield
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