刈割对UV-B辐射增强下紫花苜蓿光合及荧光特性的影响

Effects of cutting on photosynthetic and chlorophyll fluorescence parameters of Medicago sativa under enhanced UV-B radiation

以紫花苜蓿(金皇后)为试验材料,UV-B辐射增强5%(T_1)和增强10%(T_2),研究了当年生紫花苜蓿光合荧光特性和地上生物量在重度刈割下对增强UV-B辐射的响应。结果表明:在刈割前后两个生育期中,与CK相比,随着UV-B强度增加各指标均呈下降趋势;在T_1处理下,与刈割前相比,刈割后紫花苜蓿Chla、Chlb、Chl(a+b)、净光合速率和荧光参数F_v/F_m在分枝期和结荚期均显著增加;在T_2处理下,在分枝期和结荚期,刈割也显著增强了紫花苜蓿Chla、Chlb、Chl(a+b)、净光合速率和F_v/F_m,增幅分别高达32%、30%、20%、17%和22%;地上生物量随着生育期的推进而增加,与刈割前相比,刈割后T_1和T_2处理的增幅分别高达49%和199%;方差分析表明,刈割与增强UV-B处理对紫花苜蓿光合特性和荧光参数的交互作用不明显;表明适度刈割在一定程度上可以缓解UV-B辐射对紫花苜蓿造成的伤害。

This paper investigated the photosynthetic fluorescence properties and aboveground biomass of current-year o sativa （Golden Empress） in response to enhanced U V-B radiation by 5% （T1） and 10% （T2） under severe cutting. The results indicated that, with the increase of UV-B radiation, all the experimental indicators declined significantly compared with those of CK in each growth stage. After cutting, the contents of Chla, Chlb and Chl（a＋b）, net photosynthetic rate and fluorescence parameter Fv/Fm of M. sativa increased significantly at the low dose of UV-B radiation （T1） in the branching stage and podding stage. At the high dose of UV-B radiation （T2）, cutting significantly enhanced those five indicators by 32%, 30%, 20%, 17% and 22% respectively in the branching period and podding period. The aboveground biomass after severe cutting increased by 49% and 199% after T1 and T2 treatments, respectively. The cutting and the enhanced UV-B radiation did not show significant interaction on photosynthesis and fluo- rescence of M. sativa. So it was concluded that moderate cutting can alleviate the damage of UV-B radiation on M. sativa to a certain extent.