烯效唑对盐胁迫下糜子幼苗形态和生理特性的调控效应

为探究叶面喷施烯效唑对糜子幼苗耐盐性的调控作用,以榆糜3号为试验材料,采用砂培方式,研究了三叶一心期叶面喷施烯效唑(50 mg·L^-1)对150 mmol·L^-1 NaCl盐胁迫下糜子幼苗生长和生理特性的影响。结果表明: 喷施烯效唑提高了盐胁迫下糜子幼苗叶片净光合速率、蒸腾速率、气孔导度和胞间CO₂浓度,同时烯效唑增加了盐胁迫下糜子叶片光系统II的最大光能转换效率、实际光化学效率和光化学猝灭系数,降低了叶片PSⅡ的非光化学猝灭系数;盐胁迫下喷施烯效唑处理株高显著降低(P<0.05),叶面积和地上部干重减小,糜子幼苗总根长、根体积、根总表面积、根平均直径和地下部干重增加;盐胁迫下经烯效唑处理的幼苗叶片和根系超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性、可溶性蛋白含量均升高;而丙二醛(MDA)含量和超氧阴离子自由基($\mathop{}_{A}^{B}$)含量均下降;其中POD活性和$\mathop{}_{A}^{B}$含量在叶片中无显著差异,而在根系中差异达显著水平(P<0.05)。因此,在三叶一心期叶面喷施50 mg·L^-1烯效唑能够调控糜子幼苗形态特征,增强根系和叶片保护酶活性和可溶性蛋白含量,减缓膜脂过氧化程度,从而有效提高植株的耐盐能力。

Effects of uniconazole on morphology and physiological characteristics of proso millet seedlings under salt stress

The aim of this research was to investigate the effect on seedling morphology and physiological characteristics of foliar uniconazole spraying of ‘Yumi 3’ proso millet seedlings under salt stress. Leaf photosynthetic characteristics, seedling growth and seedling antioxidase systems were measured, following foliar spraying with uniconazole (50 mg·L^-1), in plants grown under 150 mmol·L^-1 NaCl stress in sand culture experiments. The results showed that foliar uniconazole spraying increased net photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO₂ concentration, maximum light energy conversion efficiency, actual photochemical efficiency and photochemical quenching of the seedlings, but decreased non-photochemical quenching coefficient. In seedlings exposed to salt stress and foliar spraying with uniconazole, seedling height decreased significantly (P<0.05), and leaf area and shoot dry weight also decreased. However, the total root length, root volume, root surface area, root average diameter and root dry weight of seedlings increased. With respect to antioxidase systems, in seedlings treated with uniconazole under salt stress, superoxide dismutase activity, peroxidase (POD) activity, catalase activity and soluble protein content were all increased, while malondialdehyde content and superoxide anion content ($\mathop{}_{A}^{B}$) were decreased. Among these parameters, POD activity and $\mathop{}_{A}^{B}$ levels showed no significant differences in leaves, but significant differences in roots (P<0.05). Therefore, foliar uniconazole (50 mg·L^-1) spraying at the three-leaf-and-one-leaflet stage of development effectively improved the salt tolerance of proso millet seedlings by regulating the seedling morphological characteristics, enhancing the protective enzyme activity and soluble protein content in the roots and leaves, and decreasing the degree of membrane lipid peroxidation.