Mycorrhizal dependency of mangaba tree under increasing phosphorus levels

Júlio Alves Cardoso Filho,Luis Carlos Caetano,Eurico Eduardo Pinto De Lemos,Tania Marta Carvalho Dos Santos,Marco Antonio Nogueira

doi:10.1590/s0100-204x2008000700013

Júlio Alves Cardoso Filho, Luis Carlos Caetano + Show 3 more

Open Access

https://doi.org/10.1590/s0100-204x2008000700013

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Abstract

The objective of this study was to evaluate the mycorrhizal dependency of mangaba tree (Hancornia speciosa) plantlets, under increasing levels of phosphorus fertilization. The experimental design was completely randomized in a 4×5 factorial arrangement with three mycorrhizal fungi inocula - Gigaspora margarita, Glomus etunicatum, or a pool of native mycorrhizal fungi (Acaulospora longula, Glomus clarum, Gigaspora albida, Paraglomus sp.) -, and a nonmycorrhizal control, in combination with five levels of phosphorus applied to the substrate: 0, 25, 50, 75, and 100 mg kg-1. After 180 days of growth, plantlets with inoculation of native mycorrhizal pool produced more shoot and root dry biomass and had higher shoot phosphorus content and accumulation. The noninoculated control showed the lowest values, independently of the phosphorus level. The highest relative mycorrhizal dependency occurred with the inoculation of native mycorrhizal fungi. Plants with mycorrhizal fungi did not respond to phosphorus addition above 50 mg kg-1. Mangaba tree is highly dependent on mycorrhiza, but the degree of dependency varies according to phosphorus levels and fungal inocula. In general, mangaba tree is more responsive to mycorrhizal fungi inoculation than to phosphorus addition.

Highlights

The mangaba tree (Hancornia speciosa Gomes) (Apocynaceae) is a native Brazilian fruit, which occurs naturally on low-fertility soils in the coastal areas and in the biome Cerrados (Aguiar Filho et al, 1998)
The experimental design was completely randomized in a 4×5 factorial arrangement, consisting of three mycorrhizal inocula: Gigaspora maragarita Becker & Hall, Glomus etunicatum Becker & Gerdemann, or a pool of native arbuscular mycorrhiza (AM) fungus (Acaulospora longula Spain & Schenck, Glomus clarum Nicol. & Schenck, Gigaspora albida Schenck & Smith and Paraglomus sp.), and a nonmycorrhizal control, in combination with five P levels in the growing substrate: 0, 25, 50, 75 and 100 mg kg-1, with five replicates
In plants infected with the native AM pool, maximum shoot and root biomasses were reached above 50 mg kg-1 of added P, the maximum point described by the quadratic regression adjustment, followed by a decrease thereafter

Summary

Introduction

The mangaba tree (Hancornia speciosa Gomes) (Apocynaceae) is a native Brazilian fruit, which occurs naturally on low-fertility soils in the coastal areas and in the biome Cerrados (Aguiar Filho et al, 1998). It has been reported that dependency on mycorrhiza varies between and within plant species (Cavalcante et al, 2001; Zangaro et al, 2007) and those with shorter root length and greater diameter usually benefit more from mycorrhizal symbiosis (Zangaro et al, 2005). Morphological root traits, such as root geometry, rate of root growth, density and length of root hairs have often been used as indicators of mycorrhizal dependency (Zangaro et al, 2007)

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