为明确烟草漂浮育苗的适宜氮肥量，以烤烟“K326”品种为材料，研究了不同施氮量对烟苗生长发育和生理特征的影响。结果表明，较低的施氮量有利于烟苗细根数量增加和根系活性提高，从而增强根系吸收能力；同时，低施氮量也显著提高了与抗性相关的过氧化物酶（ POD）、多酚氧化酶（ PPO）和苯丙氨酸酶（ PAL）活性，增强了烟苗对病原物的抵抗力。适宜的施氮量能显著提高烟苗叶片光合速率（Pn）、胞间CO2浓度（Ci）、蒸腾速率（Tr）和水分利用率（WUE）。因此，在烟草漂浮育苗过程中，施氮量以6～11 mg／株为宜，更有利于培育根系发达、抗病性强的健康烟苗。%This study investigated the influence of the application amounts of nitrogen on the growth and physiological charac-teristics of tobacco seedlings by studying flue-cured tobacco K326, the appropriate amount of nitrogen fertilizer needed for tobacco seedlings grown in floating beds was determined .Results showed that applying small amount of nitrogen increased the number of tobacco seedling roots and improved root activity, thus enhancing root adsorption.Moreover, it also significantly increased the ac-tivity of resistance-related peroxidase, polyphenol oxidase, and phenylalanine and reinforced the resistance of tobacco seedlings to pathogens.Applying appropriate amount of nitrogen could significantly increase the photosynthetic rate of tobacco seedling leaves , intercellular CO2 content, transpiration rate, and water use efficiency.The amount of nitrogen appropriate in the process of growing tobacco seedlings on a floating bed was 6~11 mg/plant, this nitrogen concentration was conducive to the growth of healthy tobacco seedlings with strong roots and resistance .
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