[en] The arbuscular mycorrhizal (AM) status [total AM colonization (RLT), percentage of root length with arbuscules (RLA) and vesicles (RLV), spore density and hyphal length density], microbial populations and soil enzyme activities were investigated in citrus (Satsuma Mandarin grafted on Poncirus trifoliata L. Raf) orchards. Two types of no-tillage soil management, natural grass cover and use of herbicides, were employed in these orchards. The citrus AM colonization (37.26-70.09%) was high in all the experimental orchards sampled. The highest RLA (43.83%), spore density (384.63 spores/100 g soil), hyphal length density (4.09 m g–1 soil), rhizospheric microbial populations and enzyme activities were observed in the orchards with a natural grass cover, and the lowest values, except urease activity, were found in the orchards treated with herbicides. Spore density, hyphal length density, catalase activity and phosphatase activity varied notably between no-tillage/natural grass and no-tillage/herbicides treated orchards in the soil layers above 40 cm. A correlation analysis showed that the hyphal length density and organic matter were significantly positively correlated. Soil enzyme activities, except phosphatase, were strongly correlated with the bacteria populations. The data presented here demonstrates that the RLA, spore density, hyphal length density, rhizospheric microbe populations and enzyme activities were significantly better in the soil layers above 40 cm of orchards with a natural grass cover than herbicidetreated soils. So, the establishment of a natural grass cover benefits soil quality in citrus orchards in Southern China.

[es] Se investig&oacute; en huertos de mandarino Satsuma injertado sobre Poncirus trifoliata L. Raf el estado de las micorrizas arbusculares (AM) [colonizaci&oacute;n total de AM (RLT), % de longitud de la ra&iacute;z con arb&uacute;sculos (RLA) y ves&iacute;culas (RLV), densidad de esporas y de hifas], las poblaciones microbianas y las actividades enzim&aacute;ticas del suelo. En estos huertos se emplea dos tipos de gesti&oacute;n del suelo sin labranza, uno mediante cubierta de c&eacute;sped natural y otro mediante uso de herbicidas. La colonizaci&oacute;n de AM en la ra&iacute;z de los c&iacute;tricos fue alta (37,26-70,09%) en todos los huertos muestreados. Se observ&oacute; el mayor RLA (43,83%), densidad de esporas (384,63 esporas/100 g de suelo), densidad de longitud de hifas (4,09 m g&ndash;1 de suelo), poblaciones microbianas rizosf&eacute;ricas y actividades enzim&aacute;ticas en los huertos con cubierta de c&eacute;sped natural. En las capas del suelo hasta los 40 cm, la densidad de las esporas y de las hifas, y la actividad de la catalasa y de la fosfatasa variaron notablemente entre los dos tratamientos. Un an&aacute;lisis de correlaci&oacute;n mostr&oacute; que la densidad de las hifas y la materia org&aacute;nica estaban significativamente correlacionadas. Las actividades enzim&aacute;ticas del suelo, a excepci&oacute;n de la fosfatasa, estuvieron fuertemente correlacionadas con las poblaciones de bacterias. Por lo tanto, la no labranza y el establecimiento de una cobertura de c&eacute;sped beneficia la calidad del suelo en estos huertos de c&iacute;tricos en el sur de China.