二甲四氯胁迫对谷子幼苗叶片衰老特性和内源激素含量的影响

【目的】研究除草剂二甲四氯对谷子叶片衰老特性以及叶片内源激素含量的影响,探讨谷子幼苗对二甲四氯胁迫的生理反应,为谷子抗除草剂胁迫机制及除草剂的安全使用提供理论依据。【方法】采用盆栽试验方法,选用晋谷21号和张杂10号为试验材料,设置二甲四氯剂量分别为0.75、1.50、3.00和6.00 kg·hm^-2 4个水平。处理后5和15 d,测定谷子幼苗株高、叶面积、叶绿素含量、光合参数、叶绿素荧光参数、丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和内源激素含量的变化,并分析了二甲四氯处理下谷子叶片中内源激素含量与光合特性参数、抗氧化酶活性间的相关性。【结果】与对照相比,喷施不同剂量二甲四氯均抑制了谷子的株高和光合作用,谷子叶片的叶绿素含量、净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、PSⅡ最大光化学效率(F_v/F_m)和电子传递速率(ETR)均出现不同程度降低;而非光化学猝灭(NPQ)的变化呈相反趋势...

Effect of MCPA on Leaf Senescence and Endogenous Hormones Content in Leaves of Foxtail Millet Seedlings

【Objective】The objective of the experiment was to investigate the effect of MCPA on the senescence characteristics of leaves and contents of endogenous hormones in leaves of foxtail millet, and explore the physiological response of foxtail millet seedlings to MCPA stress, which provided a theoretical basis for the mechanism of herbicide resistance and the safe use of herbicide during cultivation.【Method】A pot-grown experiment was conducted with Jingu 21 and Zhangza10 as materials with four dosages (0.75, 1.50, 3.00, 6.00 kg·hm ^-2) of MCPA. After treatment for the 5 d and 15 d, the plant height, leaf area, chlorophyll content, photosynthetic parameters, chlorophyll fluorescence parameters, malondialdehyde (MDA) content, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activity and endogenous hormone content of foxtail millet were determined. In addition, the correlation between endogenous hormone content and photosynthetic characteristics and antioxidant enzyme activity under MCPA stress were analyzed.【Result】Compared with the control, the chlorophyll content, net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), PSⅡ maximum photochemical efficiency (F_v/F_m), and electron transfer rate (ETR) in foxtail millet leaves were decreased with different MCPA dosages treatment; however, the change tendency of non - photochemical quenching (NPQ) is opposite. In addition, the effect of MCPA on the photosynthetic characteristics of foxtail millet gradually decreased with the extension of application time, which showed that most indexes could be restored to the control level after MCPA treatment 15 d. At the same time, SOD, POD, CAT activity and MDA content of foxtail millet leaves were increased with MCPA treatment at different dosages, which showed the trend of increasing first and then decreasing with the extension of application time. MCPA treatment increased abscisic acid (ABA) and auxin (IAA) content in foxtail millet leaves and decreased gibberellin (GA) and zeatin (Zt) content in foxtail millet leaves. ABA content was significantly negatively correlated with chlorophyll content, P_n, F_o and ETR, and significantly negatively correlated with G_s. Except NPQ, Zt content was significantly positively correlated with chlorophyll content and ETR, and significantly positively correlated with F_o. Correlation analysis showed that ABA content was significantly correlated with the activity of SOD and POD. IAA content was positively correlated with CAT. GA content was significantly correlated with POD activity.【Conclusion】 After MCPA treatment, Zt content was increased and ABA content was decreased in foxtail millet leaves. On the one hand, MCPA affected photosynthetic rate, photoelectron transfer and other photosynthetic physiological processes; while, MCPA regulated endogenous hormone contents including IAA, GA and ABA, which further influence the activity of SOD, POD and CAT and eventually leaded to enhance the tolerance to herbicide stress.