To improve crop yields the application of fertilizers to provide nutrients to soils is recommended. An alternative option to substitute nutritional supplements of chemical origin is the use of biofertilizers. This study evaluated the effectiveness of a biofertilizer of natural origin, Macrocystis pyrifera algal extracts and its combination with the plant growth–promoting bacterium Azospirillum brasilense, on the germination and establishment of lettuce seedlings (Lactuca sativa) under two different water irrigation treatments. Results demonstrated that germination energy and germination power improved upon inoculation of lettuce seeds with the seaweed extract. After 7 days of culture, seedlings showed increased root growth which would help to ensure their establishment. The application of bacteria and algae individually or in combination exerted a positive effect on lettuce plant growth compared with controls (without applications). In addition, treatments with the brown seaweed extract favoured seedlings adaptation to an unfavourable environment (water deficit) by increasing their root mass and protecting them from the negative effects imposed by stress. These results suggest that the use of M. pyrifera extract to improve plant growth and to provide stress protection may be considered an interesting tool for agricultural purposes. Nevertheless, when A. brasilense (whose plant growth–promoting properties are largely known) is combined with the brown seaweed extract, a new biofertilizing formula is obtained and proposed for future seed inoculation technology, based on the promising effects observed in this work.

为了提高作物产量，建议使用肥料为土壤提供养分。替代化学来源的营养补品的替代选择是使用生物肥料。这项研究评估了天然来源的生物肥料，大孢子藻（Macrocystis pyrifera）藻提取物及其与植物生长促进细菌巴西细螺旋藻（Azospirillum brasilense）的结合对生菜幼苗（Lactuca sativa）萌发和定殖的有效性。）在两种不同的灌溉方式下进行。结果表明，用海藻提取物接种生菜种子后，发芽能和发芽能力得到改善。培养7天后，幼苗的根系生长增加，这将有助于确保其定植。与对照相比（不施用），单独或组合施用细菌和藻类对莴苣植物的生长产生积极影响。此外，用棕色海藻提取物进行处理有利于幼苗增加根系质量并保护其免受胁迫的不利影响，从而使其适应不利的环境（缺水）。这些结果表明使用了M. pyrifera提取物改善植物生长并提供胁迫保护可能被认为是用于农业目的的有趣工具。然而，当巴西盲。（其具有促进植物生长的特性广为人知）与棕色海藻提取物结合使用时，基于这项工作中观察到的有希望的效果，就获得了一种新的生物肥配方，并建议用于未来的种子接种技术。