Trichoderma is a rhizosphere fungus widely used in agriculture due to the variety of mechanisms of biological control. It can establish a direct relationship with the plant root cells, modifying the morphology and physiological processes, conferring a better defensive capacity against the attack of pathogens in the soil. This research aimed to study the interaction of T. asperellum, T. harzianum, T. virens, Setophoma terrestris and Sclerotium cepivorum on onion roots (Allium cepa), both in vitro and in field trials, to evaluate the histological modifications and the effect on in vitro growth promotion, and to test the effect of Trichoderma in the field, over the incidence of these pathogens and the crops harvest. In vitro plant promotion assay was made using T. asperellum, T. harzianum, and T. virens to test their effect on the development of onion seedlings from disinfected seeds. Roots of these plants were subjected to histological analysis using Transmission Electronic Microscopy (TEM) to examine changes in cell structure. This analysis also included the pathogens S. cepivorum and S. terrestris, the major soilborne pathogens of onion worldwide. To verify the effect of the Trichoderma species used in the study, a field experiments were performed where the fresh and dry weight of onion bulbs and the incidence of pathogens were measured. Histological modifications were observed in the root cells in the different treatments and were related to the effects caused for Trichoderma. It was shown that although T. asperellum did not stimulate in vitro root growth it can have an important effect in the field by reducing the incidence of S. cepivorum and S. terrestris while improving the onion’s harvest. On the contrary, species that have a root promoting effect do not necessarily improved yield. Besides, rather than this study, there are no other histological studies published in the onion- S. terrestris pathosystem.

木霉属是一种根际真菌，由于其多种生物控制机制而广泛用于农业。它可以与植物的根细胞建立直接的联系，改变其形态和生理过程，赋予抵抗土壤中病原体侵袭的更好的防御能力。这项研究旨在研究洋葱根（Allium cepa）上的曲霉，哈茨木（T. harensianum），毒藤（T. virens），土oph（Setophoma terrestris）和头孢菌核菌（Sclerotium cepivorum）之间的相互作用，以评估其组织学修饰及其对洋葱根的影响。促进体外生长，并测试木霉的作用在田间，这些病原体的发病率和农作物的收成。体外植物促进测定使用由T.棘孢，哈茨木霉，和绿木霉测试他们对洋葱幼苗从消毒种子发育的效果。使用透射电子显微镜（TEM）对这些植物的根进行组织学分析，以检查细胞结构的变化。该分析还包括致病菌cepivorum和S. terrestris，它们是全世界洋葱的主要土壤传播病原体。验证木霉的作用在该研究中使用的两个物种中，进行了田间试验，其中测量了洋葱鳞茎的干重和干重以及病原体的发生率。在不同处理中观察到根细胞的组织学改变，并与木霉菌的作用有关。结果表明，虽然T.棘孢没有体外根生长刺激它可以通过减少其发病率在该领域的一个重要效果S. cepivorum和S.蒺藜同时改善洋葱的收成。相反，具有根促进作用的物种并不一定提高产量。除此之外，没有其他组织学研究发表在洋葱上。 病理系统。