开放式空气CO2浓度升高对小麦冠层微气候的影响

Effects of Free-air CO_2 Enrichment(FACE) on Wheat Canopy Microclimate

利用农田开放式CO2浓度升高(Free-air CO2Enrichm ent,简称FACE)系统平台,于小麦拔节-成熟期进行作物冠层微气候要素的连续观测。结果表明:FACE条件下叶片气孔导度低于对照,倒一、倒二、倒三叶的气孔导度比对照平均分别减少了28%、32%和26%,均达极显著水平(p<0.01);由于叶片气孔导度降低使得蒸腾降温作用减弱,导致白天FACE条件下小麦的冠层温度升高,开花-蜡熟期平均升高0.77℃,抽穗后最高达1.58℃;FACE系统中,白天小麦冠层内部空气温度比对照高0.12~0.98℃(最大差值),冠层顶部空气温度高0.03~0.7℃(最大差值),但冠层空气湿度均低于对照,冠层中部空气湿度最低差值在-0.3^-7个百分点;FACE处理对小麦冠层上方净辐射的影响不大。

The Free-air CO2 Enrichment （FACE） system was used to investigate the effect of FACE on wheat canopy microclimate. The wheat canopy microclimate observations were carried out during elongation and mature stages. The results showed that the FACE extreme significantly reduced the wheat leaf stomatal conductance in upper, middle and lower leaves compared with the check by 28% ,32% , and 26% （ p 〈 0. 01 ） respectively. The maximum daytime mean temperature difference of the vegetation canopy between FACE and ambient reached at 1.58℃ in response to stomatal closure under E-CO2 at the flowering stage. The maximum daytime air temperature difference varied between 0. 12 and 0.98℃ inside the canopy, and 0.03 - 0.7℃ at the canopy top. Whereas daytime air humidity inside the canopy was lower in FACE plot than in ambient plot. The maximum claytime air humidity difference between FACE and ambient varied between -0.3% - -7% at about 14：00. The net radiation above wheat canopy was not significantly affected by FACE.