一氧化氮(NO)熏蒸蒜瓣对蒜苗叶片光合作用的影响

以白皮改良蒜为试验材料，用不同浓度的一氧化氮气体（0.1、0.5、1.0 μmol·L^-1）在无氧环境中对大蒜进行熏蒸。并使用TPS 1便携式光合仪结合Farquhar和Sharkey的理论测定或计算NO处理蒜苗的相关光合指标,同时测定核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)含量。发现与1.0 μmol·L^-1 NO气体处理相比，0.5 μmol·L^-1 NO处理的蒜苗叶片净光合速率（P_n）、气孔导度(G_s)提高、而胞间隙CO₂浓度（C_i）、气孔限制值(L_s)降低，说明0.5 μmol·L^-1 NO处理下蒜苗光合速率高于1.0 μmol·L^-1 NO的处理的主要是非气孔因素。而且0.5 μmol·L^-1 NO处理提高了蒜苗叶片表观量子效率(AQY)、表观羧化效率(CE)和光合能力(A_o)及Rubisco含量，说明外源NO处理提高了蒜苗叶片光合作用过程中光反应能力和碳同化过程中羧化酶羧化效率。与对照相比，1.0 μmol·L^-1 NO处理降低了蒜苗叶片净光合速率，同时气孔导度、胞间隙CO₂浓度、表观量子效率、Rubisco含量、羧化效率和光合能力均降低，而气孔限制值升高，说明1.0 μmol·L^-1 NO对蒜苗光合作用的抑制既有气孔因素，也有非气孔因素。而0.1 μmol·L^-1 NO处理各项指标与对照无显著性的差异。

Effect of Nitric Oxide(NO)Fumigation on the Photosynthesis of Garlic Sprouts

The white garlic were fumigated with different concentrations of NO gas (0.1, 0.5, 1.0 μmol·L^-1) under anaerobic conditions. The photosynthetic parameters of garlic sprouts were determined with TPS-1 photosynthesis system or calculated according to the theory of Farquhar and Sharkey. The content of RuBP carboxylase-oxygenase (Rubisco) was also assayed simultaneously. Compared to 1.0 μmol·L^-1 NO treatment, 0.5 μmol·L^-1 NO resulted in increases in net photosynthetic rate (P_n) and stomatal conductance (G_s) ,which were accompanied by decreases in intercellular CO₂ concentration (C_i) and stomatal limitation values (L_s) in garlic sprouts. The results showed that the main reason of photosynthetic rate in garlic sprouts treated with 0.5 μmol·L^-1 NO was higher than 1.0 μmol·L^-1 NO was caused by non stomatal factor. Furthermore, 0.5 μmol·L^-1 NO enhanced apparent quantum yield(AQY), carboxylation efficiencies(CE), photosynthetic capacity(A_o), Rubisco content, These results indicated that exogenous NO can improved ability of light reaction, the efficiency of carbon assimilation of and stomatal limitation values in garlic sprouts. Compared to control treatment，1.0 μmol·L^-1 NO caused the reduction of P_n, G_s, C_i, AQY，Rubisco content, CE and the enhancement of L_s in garlic sprouts. These results showed that the inhibitive effect of 1.0 μmol·L^-1 NO treatment on photosynthetic of garlic sprouts caused by stomatal factor and non stomatal factor together. However, all parameters of 0.1 μmol·L^-1 NO treatment had no difference.