Nitrogen increases drought tolerance in maize seedlings
Nitrogen increases drought tolerance in maize seedlings
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DOI：
10.1071/fp18186
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发表时间：
2019-01-01
影响因子：
3
通讯作者：
Sui, Na
中科院分区：
文献类型：
--
作者：
Song, Yushuang;Li, Jinlu;Sui, Na
干旱和氮肥利用率是影响植物生长和植物全球分布的两个重要环境因素。我们使用三种氮浓度（0.5、7.5 和 15mM）和三种可用水水平（正常条件、轻度干旱和严重干旱）研究了氮对干旱胁迫下玉米幼苗叶片 PSII 的影响。芽鲜重和干重以及根鲜重随着干旱条件的增加而下降。遭受干旱胁迫的玉米叶片中叶绿素a（Chl a）和叶绿素b（Chl b）含量、净光合速率、蒸腾速率、气孔导度、最大化学效率（F-v/F-m）和PSII光化学效率（phi PSII）均显着降低。适量施氮缓解了干旱胁迫，增强了光合能力。干旱胁迫下玉米叶片中丙二醛、H2O2 和 O-2（-中心点）积累。轻度干旱胁迫下玉米叶片超氧化物歧化酶和抗坏血酸过氧化物酶活性增加，但重度干旱胁迫下显着降低。干旱胁迫下玉米叶片NO3-含量和硝酸还原酶（NR）活性显着降低，而适度施氮则促进NO3-积累和硝酸还原酶活性增加。脱落酸含量显着增加；这种增加与干旱胁迫下的氮浓度呈正相关。总之，这些结果表明，适度的氮供应增加了植物对干旱胁迫的抵抗力，而高或低的氮浓度增加了玉米对干旱胁迫的敏感性。这些发现对于指导氮肥的农业使用具有重要意义。
Drought and nitrogen availability are two important environmental factors that affect plant growth and the global distribution of plants. We examined the effect of nitrogen on PSII in the leaves of maize seedlings under drought stress using three nitrogen concentrations (0.5, 7.5 and 15mM) and three levels of water availability (normal conditions, mild drought and severe drought). Shoot fresh and dry weights and root fresh weight decreased with increasing drought conditions. In maize leaves subjected to drought stress, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, net photosynthetic rate, transpiration rate, stomatal conductance, maximum chemical efficiency (F-v/F-m), and photochemical efficiency of PSII (phi PSII) were significantly reduced. Moderate nitrogen supply relieved the drought stress and enhanced the photosynthetic capacity. Malondialdehyde, H2O2 and O-2(-center dot) accumulated in maize leaves under drought stress. Superoxide dismutase and ascorbate peroxidase activities increased in maize leaves under mild drought stress, but were significantly reduced under severe drought stress. The NO3- content and nitrate reductase (NR) activity of maize leaves were significantly reduced under drought stress, while moderate nitrogen supply promoted the accumulation of NO3- and an increase in the nitrate reductase activity. The abscisic acid content increased significantly; this increase was positively correlated with the nitrogen concentration under drought stress. Together, these results indicate that moderate nitrogen supply increases plant resistance to drought stress, while high or low nitrogen concentrations increase the sensitivity of maize to drought stress. These findings are important for guiding the agricultural use of nitrogen fertilisers.