This work focuses on the investigation of forage crops hybrid fescue and legume alfalfa response to drought at different levels of nitrogen fertilization. Plants were grown in pots filled with a mixture of field soil, perlite and fine sand with three (N0, N60 and N90 kg/ha) levels of nitrogen fertilization in a greenhouse. Drought stress was applied by withholding watering for 1 week, after which plants were left for a recovery period of 1 week. In most cases, the morphological indices of alfalfa did not differ significantly between the treatments. In contrast, the above-ground biomass of fescue grown under well-watered conditions was largely enhanced by N addition. The main trend of JIP test parameters was that nitrogen fertilizer did not have a significant effect on alfalfa. Contrarily, additional nitrogen content increased energy fluxes (such as absorption, trapping, electron transport, reduction of end acceptors) and density of reaction centres not only in well-watered but also in drought-affected fescue plants. An increase in nitrogen fertilizers increased content of pigments and flavonoids in fescue leaves. In conclusion, the stress tolerance index of hybrid fescue increased along with the increase in N content due to more efficient use of light energy and increased antioxidative capacity, all of which led to significantly higher production of above-ground biomass at higher N levels and drought stress.

中文翻译：

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补氮可减轻非豆科杂交植物羊茅的干旱胁迫且不影响紫花苜蓿的固氮

这项工作的重点是研究牧草杂交羊茅和豆科苜蓿在不同施氮水平下对干旱的响应。在温室中将植物种植在充满田间土壤、珍珠岩和细沙的混合物的盆中，并在温室中施以三种（N0、N60 和 N90 kg/ha）水平的氮肥。通过停止浇水 1 周来施加干旱胁迫，然后将植物放置 1 周的恢复期。在大多数情况下，紫花苜蓿的形态指标在处理之间没有显着差异。相比之下，在充分浇水的条件下生长的羊茅的地上生物量通过添加氮而大大提高。JIP试验参数的主要趋势是氮肥对苜蓿的影响不显着。相反，额外的氮含量增加了能量通量（例如吸收、捕获、电子传递、末端受体的减少）和反应中心的密度，不仅在水分充足的植物中而且在受干旱影响的羊茅植物中也是如此。氮肥的增加增加了羊茅叶中色素和类黄酮的含量。总之，由于更有效地利用光能和提高抗氧化能力，杂交羊茅的胁迫耐受指数随着氮含量的增加而增加，所有这些都导致在更高的氮水平和干旱条件下地上生物量的产量显着增加压力。氮肥的增加增加了羊茅叶中色素和类黄酮的含量。总之，由于更有效地利用光能和提高抗氧化能力，杂交羊茅的胁迫耐受指数随着氮含量的增加而增加，所有这些都导致在更高的氮水平和干旱条件下地上生物量的产量显着增加压力。氮肥的增加增加了羊茅叶中色素和类黄酮的含量。总之，由于更有效地利用光能和提高抗氧化能力，杂交羊茅的胁迫耐受指数随着氮含量的增加而增加，所有这些都导致在更高的氮水平和干旱条件下地上生物量的产量显着增加压力。