Survey of vesicular–arbuscular mycorrhizae in lettuce production in relation to management and soil factors

Abstract

The occurrence of vesicular–arbuscular mycorrhizae (VAM) root colonization and spore number in soil was assessed for 18 fields under intensive lettuce (Lactuca sativa L.) production in California during July and August of 1995. Data on management practices and soil characteristics were compiled for each field, and included a wide range of conditions. The relationship between these factors and the occurrence of VAM in these fields was explored with multivariate statistical analysis. VAM colonization of lettuce tended to decrease with the use of chemical inputs, such as pesticides and high amounts of P and N fertilizers. Addition of soil organic matter amendments, the occurrence of other host crops in the rotation, and soil carbon[ratio ]phosphorus and carbon[ratio ]nitrogen ratios, were positively associated with VAM colonization of lettuce roots. The number of VAM spores in soil was strongly correlated with the number of other host crops in the rotation, the occurrence of weed hosts and sampling date, but was more affected by general soil conditions than by management inputs. Higher total soil N, C and P, as well as CEC, were inversely related to soil spore number. A glasshouse study of the two primary lettuce types sampled in the field showed no significant differences in the extent of root colonization under similar growing conditions. The results of this study are compared with other studies on the effects of management and soil conditions on mycorrhizal occurrence in agriculture.

The Influence of Bioproducts on Mycorrhizal Occurrence and Diversity in the Rhizosphere of Strawberry Plants under Controlled Conditions

“…Use of readily soluble fertilisers, particularly N fertilisers, as well as P fertilizers, has been reported to have a negative impact on AM colonisation and/or diversity in some cases [50]- [54]. The latter effect has been observed also in our trial, since after application of NPK only the two most frequent species (Claroideoglomus claroideum and Rhizophagus fasciculatus) were present in the trap culture ( Table 3).…”

“…The latter effect has been observed also in our trial, since after application of NPK only the two most frequent species (Claroideoglomus claroideum and Rhizophagus fasciculatus) were present in the trap culture ( Table 3). The limited root colonization and diversity of species present after the treatment with Manure was partly unexpected since farmyard manure does not seem to suppress AMF and may even stimulate them [50] [55]- [57]. However, overuse of organic amendments, especially those high in P, may impact negatively on AMF and the precise effect of organic amendments has been shown to be unpredictable on any given soil or with any particular amendment [58] [59].…”

Colonisation of apple and blackcurrant roots by arbuscular mycorrhizal fungi following mycorrhisation and the use of organic mulches

“…2007), including mycorrhizal fungi (Ryan et al 1994, Miller andJackson 1998) to a greater extent than conventional mineral fertilisation. Arbuscular mycorrhizal fungi play an important role in the growth and development of various plant species, including many species of crop plants (Ngosong et al 2010).…”

Micorriza arbuscular em cupuaçu e pupunha cultivados em sistema agroflorestal e em monocultivo na Amazônia Central

“…Esses resultados demonstram que o manejo pode alterar o estabelecimento e a extensão da simbiose micorrízica, como constatado com outras espécies de plantas (Fernandes & Siqueira, 1989;Kabir et al, 1997;Miller & Jackson, 1998;Galvez et al, 2001;Feldmann et al, 2002) e mais especificamente na pupunha (Bovi et al, 2000).…”

“…Sistemas de baixos insumos, cultivo mínimo, adição de matéria orgânica e diversificação de hospedeiro mediante rotação de culturas podem aumentar a colonização micorrízica (Miller & Jackson, 1998;Galvez et al, 2001).…”