Abstract This study was carried out to assess the efficiency of nitrogen (N) fertilizer in mitigating the harmful effects of salinity stress on growth and biochemical traits in sorghum genotypes. The experiment was conducted as a factorial trial based on the completely randomized design with four replications under the greenhouse conditions. The factors included four sorghum genotypes (KDFGS1, KDFGS23, KDFGS29 lines, and KFS2 cultivar), two salinity levels (3 and 12 dS m−1) and three nitrogen levels (0, 75 and 150 mg N kg−1soil). The results showed that application of nitrogen fertilizer increased photosynthetic pigments and K+/Na+ ratio in leaf sheath and root. Also, nitrogen dramatically decreased malondialdehyde (MDA) content. This was an indication of the reduced detrimental effects of salinity stress found in all genotypes. In addition, it was found that upon 150 mg N kg−1 treatments, proline (Pro) and antioxidant enzymes markedly decreased in all sorghum genotypes. The highest impact of nitrogen fertilizer for reducing the negative effect of salinity stress was observed in KFS2 (known as tolerant genotype). Due to the highest Pro accumulation in KDFGS23 (known as sensitive genotype), it did not appear to be a suitable criterion for the selection of the tolerant lines/cultivars. In general, the results suggested that using a reasonable N fertilizer level could be used as an efficient tool to improve the growth of the sorghum genotypes subjected to salinity stress and this effect was more pronounced in the tolerant genotype.

中文翻译：

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盐胁迫条件下高粱基因型对氮肥的生长及生化响应

摘要 本研究旨在评估氮肥在减轻盐分胁迫对高粱基因型生长和生化性状的有害影响方面的效率。该实验是基于完全随机设计的析因试验，在温室条件下重复四次。这些因素包括四种高粱基因型（KDFGS1、KDFGS23、KDFGS29 品系和 KFS2 栽培品种）、两种盐度水平（3 和 12 dS m-1）和三种氮水平（0、75 和 150 mg N kg-1 土壤）。结果表明，施氮肥提高了叶鞘和根部的光合色素和K+/Na+比值。此外，氮显着降低了丙二醛 (MDA) 的含量。这表明在所有基因型中发现的盐分胁迫的有害影响减少。此外，发现在 150 mg N kg-1 处理后，脯氨酸 (Pro) 和抗氧化酶在所有高粱基因型中均显着降低。在 KFS2（称为耐受基因型）中观察到氮肥对减少盐胁迫负面影响的最大影响。由于 KDFGS23 中 Pro 积累最高（称为敏感基因型），它似乎不是选择耐受品系/栽培品种的合适标准。总的来说，结果表明，使用合理的氮肥水平可以作为提高高粱基因型在盐分胁迫下生长的有效工具，这种作用在耐盐基因型中更为明显。在 KFS2（称为耐受基因型）中观察到氮肥对减少盐胁迫负面影响的最大影响。由于 KDFGS23 中 Pro 积累最高（称为敏感基因型），它似乎不是选择耐受品系/栽培品种的合适标准。总的来说，结果表明，使用合理的氮肥水平可以作为提高高粱基因型在盐分胁迫下生长的有效工具，这种作用在耐盐基因型中更为明显。在 KFS2（称为耐受基因型）中观察到氮肥对减少盐胁迫负面影响的最大影响。由于 KDFGS23 中 Pro 积累最高（称为敏感基因型），它似乎不是选择耐受品系/栽培品种的合适标准。总的来说，结果表明，使用合理的氮肥水平可以作为提高高粱基因型在盐分胁迫下生长的有效工具，这种作用在耐盐基因型中更为明显。