低磷和高照度光下两种不同磷效率玉米幼苗的几种光合参数变化

Changes in Some Photosynthetic Parameters of Maize Inbred Lines under Strong Light and Low Phosphorus Level

以完全培养液(HP,1 000μmol·L^(-1) KH_2PO_4)培养15 d的玉米自交系KH5(磷高效)和SD502(磷低效)幼苗转入低磷(LP,5μmol·L^(-1)KH_2PO_4)条件下培养20 d后,检测叶中几种与光合作用有关参数的结果表明,低磷下两自交系玉米叶中无机磷含量、植株生物量和叶片的净光合速率(P_n)均下降,KH5的降幅小于SD502。两自交系玉米叶片以高照度光(1 600μmol·m^(-2)·s^(-1))照射1h后,叶片的PSⅡ实际光化学效率(Φ_(PSⅡ))、PSⅡ最大光化学效率(F_v/F_m)和表观光合电子传递速率(ETR)均下降,而初始荧光(F_n)、非光化学猝灭(NPQ)和天线热耗散(HDR)均升高。在强光胁迫过程中,玉米幼苗叶片发生光抑制,自交系SD502在低磷下的光抑制比KH5严重。

Maize inbred lines KH5 （Pi efficient） and SD502 （Pi inefficient） were grown in high phosphate （HP, 1 000 μmol·L^-1KH2PO4） nutrient solution for 15 d, then half of seedlings continued to grow in HP condition and the other were cultured in low phosphate （LP, 5 μmol·L^-1KH2PO4） nutrient solution for 20 d. Several photosynthetic parameters of the two hydroponic maize inbred lines were measured at seedling stage under two different phosphate levels. The results indicated that low-phosphorus stress decreased the content of inorganic phosphorus in leaves of two maize inbred lines, biomass of maize seedlings and net photosynthetic rate （Pn）. The extent of decline of KH5 was less than that of SD502. When leaves of two maize inbred lines were luminated with strong light （1 600 μmol·m^-2·s^-1） for 1 h, actual PSII efficiency （ФPSII）, the maximum PSII efficiency （Fv/Fm） and the apparent photosynthetic electron transport rate （ETR） declined while initial of yield （F0）, non-photochemical quenching coefficient （NPQ） and hot dissipation of antenna （HDR） increased. During strong light stress, photoinhibition occurred in leaves of maize seedlings; and it was more significant in SD502 than in KH5.