【目的】江汉平原为湖北省小麦主产区之一，小麦孕穗至成熟期空气相对湿度偏高是限制该地区小麦籽粒产量提高的重要气候因素。随着全球气候变化，在空气温度逐年升高的同时，空气中水汽的含量也在相应增加。论文旨在研究空气相对湿度升高对小麦的产量效应，以期为提高江汉平原小麦籽粒产量奠定理论基础。【方法】在系统分析江汉平原近30年空气相对湿度分布特征的基础上，通过人工气候室等设施于小麦孕穗期进行高空气湿度处理（处理时间为10 d），并以外界空气湿度处理为对照，于处理第5天、处理第10天、恢复后第5天、恢复后第15天等时期取样，分析孕穗期空气相对湿度升高对小麦旗叶光合特性、旗叶及倒三叶SPAD值、叶片衰老进程、根系活力、株高、干物质积累量、籽粒产量及产量构成因素等的影响。【结果】（1）1983-2013年江汉平原空气相对湿度呈不规则波动，2-5年为一个周期，孕穗期空气相对湿度达78%以上年份有12个；2011-2012年度及2012-2013年度江汉平原小麦孕穗期空气相对湿度偏高，平均分别为77.4%和79.1%；表明江汉平原小麦孕穗期高空气湿度天气频繁出现。（2）人为增加空气相对湿度达100%条件下，与对照相比，旗叶及倒三叶 SPAD 值均降低，其中高空气湿度处理第5天差异不显著，第10天差异达显著水平；恢复正常空气湿度后，高空气湿度处理与对照间差异幅度缩小，但仍低于对照水平。（3）空气湿度升高对旗叶光合速率的影响与SPAD一致，即空气相对湿度升高，旗叶光合速率下降，撤除高空气相对湿度处理后，旗叶光合速率与对照间差异减小。（4）人为增加空气相对湿度达100%条件下，分析旗叶及倒三叶丙二醛含量及根系活力表明，空气相对湿度升高，叶片膜质过氧化加速、根系活力降低，撤除高空气湿度处理后，叶片膜质过氧化程度及根系活力与对照间差异幅度均减小，但仍显著低于对照水平，表明高空气湿度对叶片衰老及根系活力的副效应是不可逆转的。（5）空气相对湿度升高，植株干物质积累量及籽粒产量均显著降低，成熟期干物质积累量较对照降低5.5%，籽粒产量降低10.0%，其中籽粒产量降低归因于穗粒数和穗粒重的降低，分析表明穗粒数较对照降低6.0%，穗粒重较对照降低4.2%。【结论】在本试验条件下，孕穗期空气相对湿度升高导致小麦旗叶光合速率等光合指标下降、膜质过氧化加速、根系活力降低，最终生物产量（含株高）和籽粒产量均显著降低，其中籽粒产量的降低主要归因于穗粒数的降低，其次为穗粒重。%[Objective]Jianghan Plain is one of the most important wheat producing areas in Hubei Province, and high relative air moisture is a major limitation on wheat grain yield. Under the conditions of global climate change, relative air moisture increased as well as air temperature. This research was carried out to study the effect of increasing relative air moisture on wheat grain yield, in order to provide a theoretical basis for promoting wheat production in Jianghan Plain.[Method]The research was carried out based on the analysis of air moisture characteristics in Jianghan Plain from 1983-2013. During the experiment, air moisture was increased to 100%by artificial chamber for 10 days at booting stage of wheat, and the normal air moisture treatment was used as CK, samples were taken at 5 d, 10 d after high air moisture control, and 5 d, 15 d after recovery from all treatments. The effects of high air moisture on photosynthetic characteristics, SPAD value in flag leaf and top 3rd leaf, course of leaf senescence, root activity, plant height, and accumulation of dry matter, grain yield and yield components were studied. [Result]Air moisture from 1983 to 2013 in Jianghan Plain fluctuated with a 2-5-year circle, and the average air moisture was over 80%during booting stage in most of the years. The air moisture at booting stage in Jianghan Plain in 2011-2012 and 2012-2013 was high, and averaged 77.4% and 79.1%, respectively. Increasing air moisture at booting stage decreased SPAD value in flag leaf and top 3rd leaf, and the difference was not significant at 5 d later, but significant at 10 d later. When air moisture returned to normal, there was a difference in leaf SPAD value between high air moisture treatment and CK, but still inferior to CK. The effects of high air moisture on photosynthetic rate in flag leaf was in agreement with SPAD value. High air moisture reduced photosynthetic rate in flag leaf and removing high air moisture treatment, the difference between high air moisture treatment and CK reduced. Increased air moisture to 100%, MDA content in flag leaf and top 3rd leaf increased, suggesting that high air moisture quickened senescence in leaf. Further analysis showed that root activity reduced as well. Removing high air moisture treatment, the difference of MDA in leaf and root activity between CK and high air moisture treatment reduced, but was still significant, which mean the effects of high air moisture on the above index was not reversal. With the increasing of relative air moisture, the amount of dry matter and grain yield decreased. Compared with CK, at maturity, dry matter of high air moisture treatment decreased by 5%, and grain yield decreased 10.0%, respectively. For further analysis, the decrease of grain yield was attributed to spike weight and grain amount per spike, decreased by 6.0% and 4.2%, respectively, at maturity compared to CK. [Conclusion]Under the conditions of this experiment, high air moisture at booting stage decreased SPAD value and photosynthetic rate in flag leaf, quickened membrane peroxidating, reduced root activity, and induced to the decrease of biomass and grain yield decreased as well.
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