杂交水稻光合和荧光特性对高CO2浓度的动态响应

为探究大气二氧化碳 (CO₂) 浓度增高对杂交水稻光合和荧光特性的动态影响,利用开放式空气中CO₂浓度增高(FACE)系统,研究高CO₂浓度对大田水稻不同生育期叶片光合和荧光参数的动态影响及其种间差异。以高产杂交组合甬优2640和Y两优2号为试验材料,设置环境CO₂和高CO₂浓度2个水平,测定2个品种气体交换和荧光参数。结果表明,大气CO₂浓度升高使2个品种平均叶片净光合速率(Pn)在移栽后30、59、76、91和108 d分别增加25%、16%、25%、18%和8%,除移栽后108 d外,均达极显著水平(P<0.01);甬优2640移栽后76和91 d叶片Pn对CO₂的响应明显大于Y两优2号。除灌浆末期外,CO₂浓度升高使2个品种叶片气孔导度(Gs)和蒸腾速率(Tr)均呈下降趋势,且Y两优2号的降幅多大于甬优2640。CO₂熏蒸下叶片气孔部分关闭,但叶片胞间与周围空气中CO₂浓度之比无显著变化,甚至明显增加。大气CO₂浓度升高使2个品种灌浆末期PSⅡ最大光化学量子产量均下降4%,但对其他各期均无显著影响;除灌浆末期外,CO₂浓度升高使PSⅡ实际光量子产量和光化学猝灭均显著增加。两杂交组合叶片光合参数对高CO₂浓度的动态响应多存在种间差异,但荧光参数的响应品种间差异较小。本研究结果为增强气候假定情景下水稻响应的预测能力并制订应对策略提供了依据。

Dynamic Responses of Leaf Photosynthesis and Chlorophyll Fluorescence to Elevated Atmospheric CO2 Concentration for Two Hybrid Rice Cultivars

In order to explore the dynamic effects of elevated atmospheric carbon dioxide (CO₂) concentration on photosynthesis and fluorescence characteristics of hybrid rice, the dynamics of high CO₂ concentration on leaf photosynthetic and fluorescence parameters and its interspecies differences of rice in different growth stages of rice was studied by using Free Air CO₂ Enrichment (FACE) technology. The high-yield hybrid rice variety Yongyou2640 and Yliangyou No.2 were grown in the environmental CO₂ and the elevated CO₂ concentration from plant transplanting to grain maturity. Elevated CO₂ concentration increased the averaged net photosynthesis rates by 25%, 16%, 25%, 18% and 8% at 30, 59, 76, 91 and 108 d after transplanting, respectively. Except for 108 d, the CO₂ effects on the other measuring dates all reached significant level of P<0.01. Compared within two varieties, the responses of Yongyou2640 to elevated atmospheric CO₂ on net photosynthetic rates were greater than that of Yliangyou No.2 on 76 d and 91d. A consistent downtrend was detected on stomatal conductance and transpiration rate at different growth stages, and the decrease of Yliangyou No.2 was more than Yongyou2640 in most cases. Though stomata closed partially upon CO₂ elevation, there were no significant effect on the ratio of intercellular to air CO₂ concentration (Ci/Ca) during the first three growth stages, and Ci/Ca even increased significantly during the last two stages. In the later grain-filling stage, F_v/F_m of both rice varieties decreased by 4.0%, but there was no significant effect on the other periods. The increase of CO₂ concentration made the actual photon yield and photochemical quenching of PSⅡincrease significantly. The above results suggested there were many differences in the dynamic response of the photosynthesis parameters of the two hybrids to high CO₂ concentration, but the differences in response parameters of the fluorescence parameters were little. The results could provide a basis for enhancing the predictive ability of rice response and formulating coping strategies under climate scenarios.