Walnut trees are among the most important hardwood species in the northern hemisphere, ecologically and economically. They are mainly cultivated for timber and nut production but are also attractive ornamental trees in parks. Establishing walnut orchards is difficult because seedlings have a coarse root architecture and few of them survive to transplanting. Planting success is mainly determined by the root system morphology and the nutrient status of the seedlings, so that rhizosphere conditions are critical for plant performance. Walnut trees can associate with soil-borne arbuscular mycorrhizal fungi, which are obligate biotrophs. In this association, plant-produced carbon compounds are traded against fungus-acquired soil mineral nutrients. The beneficial effect of arbuscular mycorrhizal symbiosis on hardwood seedling quality and field performance has long been known, but an integrated view is lacking about the effects of arbuscular mycorrhizas on walnut cropping. Therefore, we surveyed the literature published over the last 40 years to provide up-to-date knowledge on the relationships between arbuscular mycorrhizas and walnut trees. Our review outlines the major following points: (1) the arbuscular-mycorrhiza-mediated nutrient uptake capacity of walnut trees is associated with first- to third-order roots, and fibrous tip-ended roots are dependent on arbuscular mycorrhizal fungi, whereas pioneer roots are not; (2) early inoculation with arbuscular mycorrhizal fungi improves the survival and seedling performance attributes of transplanted walnut trees: biotization enhances walnut transplant success by increasing the number of lateral roots and plant P uptake, but these benefits are fungus- and host-dependent; (3) in the context of walnut agroforestry, deeply rooted walnut trees play a role as reservoirs of arbuscular mycorrhizal fungal propagules for the surrounding vegetation, but tree shade and soluble phosphate availability decrease walnut mycorrhizal dependency; and (4) the arbuscular mycorrhizal mycelium mediates the transport of juglone and thus plays a role in walnut tree allelopathy.

从生态和经济角度来看，胡桃树是北半球最重要的硬木树种之一。它们主要用于木材和坚果生产，但在公园中也很有吸引力。建立核桃果园很困难，因为幼苗的根部结构较粗，几乎没有存活下来的种子。播种成功主要取决于根系形态和幼苗的营养状况，因此，根际条件对植物生长至关重要。核桃树可与土壤传承的丛枝菌根真菌结合，而后者是专性的生物养分。在这种关联中，将植物产生的碳化合物与真菌获得的土壤矿质养分进行交易。丛枝菌根共生对硬木幼苗质量和田间性能的有益作用早已为人所知，但关于丛枝菌根对核桃种植的影响尚缺乏一个综合的认识。因此，我们调查了过去40年来发表的文献，以提供有关丛枝菌根与胡桃树之间关系的最新知识。我们的综述概述了以下主要方面：（1）核桃树的丛枝菌根介导的养分吸收能力与一阶到三阶根相关，纤维尖端根取决于丛枝菌根真菌，而先驱根不是; （2）早期接种丛枝菌根真菌可改善核桃树移植的存活率和幼苗性能：生物增生通过增加侧根的数量和植物对磷的吸收，提高了核桃移植的成功率，但这些益处取决于真菌和宿主；（3）在核桃农林业中，根深蒂固的核桃树起着丛枝菌根真菌繁殖体对周围植被的贮藏的作用，但树荫和可溶性磷的利用率降低了核桃对菌根的依赖性。（4）丛枝菌根菌丝体介导胡桃木的转运，从而在核桃树化感作用中起作用。但是树荫和可溶性磷酸盐的利用率降低了核桃的菌根依赖性；（4）丛枝菌根菌丝体介导胡桃木的转运，从而在核桃树化感作用中起作用。但是树荫和可溶性磷酸盐的利用率降低了核桃的菌根依赖性；（4）丛枝菌根菌丝体介导胡桃木的转运，从而在核桃树化感作用中起作用。