UV-B增强下施硅对大麦抽穗期光合和蒸腾生理日变化的影响

通过大田模拟试验,研究UV-B增强下施硅对大麦抽穗期叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、胞间二氧化碳浓度（Ci）和水分利用效率（WUE）日变化的影响。UV-B辐射设2个水平即自然光（对照,A,1.5kJ·m-2）和UV-B增强（E,增强20%,1.8kJ·m-2）,施硅量设2个水平即Si0（不施硅）和Si1（150kg·hm-2SiO2）。结果表明,不施硅情况下（Si0）,UV-B增强处理的Pn、Tr、Gs和WUE的日平均值比自然光（A）处理分别下降23.13%、7.66%、1.07%和16.38%,而施硅情况下（Si1）则分别下降10.52%、5.71%、3.77%和12.15%,说明UV-B增强可降低大麦叶片的净光合速率、蒸腾速率和水分利用效率,而施硅可缓解UV-B增强对大麦净光合速率的抑制作用,但并不能缓解UV-B增强对大麦蒸腾作用以及气孔导度的抑制。研究结果对进一步研究UV-B增强下施硅对大麦产量和品质的影响具有积极意义。

Effects of Silicon Fertilization on Diurnal Variations of Photosynthesis and Transpiration at Barley Heading Stage under Elevated UV-B Radiation

Field simulating experiment with barley was conducted to investigate the effects of silicon （ Si ） supply on diurnal variations of net photosynthetic rate（Pn）, transpiration rate （Tr）, stomatal conductivity （Gs）, intercellular CO2 concentration （Ci） and water use efficiency （WUE） under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i. e. ambient （ A, 1.5kJ ·m-2） and elevated UV-B （ E, 1.8kJ ·m-2 ）, and two Si supply levels,i, e. SiO（0kg · ha^-1 SiOa） and Sil （150kg · ha^-1 SiO2）. The results showed that, compared with ambient UV-B radiation, elevated UV-B radiation decreased net photosynthetic rate, transpiration rate, stomatal conductivity and water use efficiency by 23.13% , 7.66% , 1.07% and 16.38% under Si0 level, respectively, and reduced by 10. 52% , 5.71% ,3.77% and 12. 15% under Sil level, respectively. This finding suggested that elevated UV-B radiation depressed net photosynthetic rate, transpiration rate and water use efficiency in barley leaves, increasing Si supply could alleviate the damage to net photosynthetic rate from elevated UV-B radiation, but not to transpiration rate and stomatal conductivity. This research will be helpful in further investigating the effect of Si supply on barley yield and quality under elevated UV-B radiation.