Owing to water scarcity and environmental hazards of synthetic fertilizers, reducing water and chemical N fertilizers is very urgent for sustainable agriculture. Thus, two field experiments were conducted to understand the physiological role of Azolla filiculoides Lam. extract (AE), as a promising biofertilizer, in enhancing growth, physiology, yield, N uptake efficiency (NUpE), N use efficiency (NUE) and irrigation water use efficiency (IWUE) in N-deficient maize plants under full and deficit irrigation. The experimental design was split plot with irrigation treatments as main plots and N treatments including full nitrogen (FN; 285 kg N ha−1), nitrogen deficiency (ND; 190 kg N ha−1) and ND (190 kg N ha−1) + AE (10% w/v) as subplots. At the vegetative stage, deficit irrigation was performed by withholding water from 26 to 56 days after sowing, while N-deficient plants received two-thirds of the total recommended N. N deficiency caused deleterious impacts on growth and yield of maize plants, particularly under deficit irrigation. However, results evidenced the role of Azolla extract, as an efficient biofertilizer, in combination with deficit irrigation in improving NUpE, NUE and IWUE without substantial decreases in grain and stover yields of N-deficient maize plants. Application of Azolla extract improved growth, yield attributes, irrigation water and N use efficiency via enhancing photosynthetic pigments, leaf water status, proline accumulation and N uptake with a reduction in membrane oxidative damage. Overall, the application of Azolla extract is an eco-friendly and cost-effective organic fertilizer to reduce more than 30% of urea fertilizer without affecting grain yield of maize plants.

中文翻译：

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满江红对缺水缺氮条件下玉米生长、生理和产量特性的影响

由于合成肥料的缺水和环境危害，减少水和化学氮肥对于可持续农业非常紧迫。因此，进行了两个田间实验以了解 Azolla filiculoides Lam 的生理作用。提取物 (AE)，作为一种有前途的生物肥料，在充分灌溉和亏缺灌溉下提高缺氮玉米植物的生长、生理、产量、氮吸收效率 (NUPE)、氮利用效率 (NUE) 和灌溉水利用效率 (IWUE) . 试验设计为裂地，灌溉处理为主，氮处理包括全氮（FN；285 kg N ha-1）、缺氮（ND；190 kg N ha-1）和ND（190 kg N ha-1） ) + AE (10% w/v) 作为子图。在营养阶段，通过在播种后 26 至 56 天停水进行亏缺灌溉，而缺氮植物接受了推荐的总氮的三分之二。氮缺乏对玉米植物的生长和产量造成有害影响，特别是在灌溉不足的情况下。然而，结果证明了满江红提取物作为一种有效的生物肥料，结合亏缺灌溉在改善 NUpE、NUE 和 IWUE 方面的作用，而不会显着降低缺氮玉米植物的谷物和秸秆产量。通过增强光合色素、叶片水分状态、脯氨酸积累和 N 吸收，减少膜氧化损伤，Azolla 提取物的应用改善了生长、产量属性、灌溉水和 N 的利用效率。全面的，