苄嘧磺隆土壤残留对玉米幼苗光合特性和叶绿素荧光参数的影响
以玉米为供试材料,采用土壤添加法研究了苄嘧磺隆残留对玉米幼苗叶片光合特性和叶绿素荧光参数的影响。结果表明,随着土壤苄嘧磺隆残留的增加,玉米幼苗株高、地上鲜重、根长和干重显著降低,高剂量的苄嘧磺隆处理导致其根冠比升高。随着苄嘧磺隆残留浓度升高,叶片SPAD值、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)及气孔限制值(Ls)均显著降低,呼吸速率(Rd)和胞间CO2浓度(Ci)显著升高；PSII的最大光化学量子产量(Fv/Fm)、黑暗中最大可变荧光强(Fv)、最大荧光(Fm)、光化学淬灭系数(qP)、PSII实际光化学量子产量Y(II)及电子传递速率(ETR)均降低,且叶片吸收的光能分配到光化学反应的比例(P)逐渐减少,而向热耗散(D)和非光化学反应(E)的分配比例逐渐增加。在苄嘧磺隆胁迫下,玉米幼苗叶片发生了光抑制,PSII复合体受损且光合电子传递受阻；玉米幼苗自身具有一定的光合保护机制,用以减轻或消除苄嘧磺隆的胁迫,增强玉米对苄嘧磺隆残留的耐受性。
英文摘要:
The influence of various levels of bensulfuron-methyl residues on the growth, photosynthetic characteristics and chlorophyll fluorescence of corn seedlings were studied by adding bensulfuron-methyl to soil in a greenhouse pot experiment. Plant height, fresh weight, root length and whole plant dry weight of corn significantly decreased with the increase of bensulfuron-methyl residue concentrations, the root/shoot ratio increased under the stress of excessive bensulfuron-methyl. SPAD value, net photosynthetic rate, stomatal limitation, stomatal conductance, transpiration rate and water use efficiency significantly declined, but intercellular carbon dioxide concentration and respiratory rate significantly increased with the increase of bensulfuron-methyl residue concentrations; the primary light energy conversion efficiency, the biggest variable fluorescence in the dark, the maximum fluorescence(Fm), photosystem II (PSII) actual photochemical efficiency, photochemical quenching and photosynthetic electron transport rate decreased, and corn seedlings had a decreased fraction of light energy allocated to photochemical reactions, while the fraction allocated to heat dissipation and non-photochemical reactions increased with bensulfuron-methyl residue increasing. The results indicated that bensulfuron-methyl might impair PSII complex and block electron transport in the light reaction of corn, and that corn seedlings might have some photosynthetic protection mechanism under bensulfuron-methyl stress.
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