Production and infectivity of inoculum of arbuscular mycorrhizal fungi multiplied in a substrate supplemented with Tris-HCl buffer

Abstract

The effect of adding Tris-HCl buffer on production and infectivity of AMF inoculum was investigated. Sporulation of Glomus etunicatum, Acaulospora longula and Gigaspora albida was improved in solution with buffer. The infectivity of G. etunicatum increased after storage, what suggests that the inoculum of this isolate is benefited by storage.Key words: mycorrhiza, organic buffer, sporulation, storage *Corresponding Author. Mailing address: Universidade Federal de Pernambuco, Centro de Ciências Biológicas, Departamento de Micologia, Recife, PE, Due to the obligate biotrophism, the production of inoculum is one of the obstacles for application of arbuscular mycorrhizal fungi (AMF) to benefit plant crops of economic importance. Among the methods for inoculum production, one is cultivation in sand and vermiculite, supplemented with nutrient solutions containing organic buffers in its formulation; this allows high production of spores (13).Organic buffers have the property of minimizing the alterations of the H + ion concentration and are used for maintaining the pH of the AMF growth media (14). The effect of a buffer on growth of AMF depends on its constitution (14) and concentration in the culture medium (12). Researches related with use of organic buffers for maintenance of pH and for stimulating mycelial growth are restricted to a few species of AMF, mostly Glomus (3,14).The AMF inoculum should be produced in high density, and maintain the infectivity and effectivity for a long period of time. Although not much information regarding storage of AMF is available (20), the maintenance of the inoculum in the conditions under which it was produced is recommended (7). It has also been mentioned that maintenance of AMF inoculum at low temperature stimulates germination and spore development (22,24); however, the ideal temperature for storage of each AMF isolate should be determined.In this work the most suitable concentration of Tris-HCl buffer for production of spores of AMF and for maintenance of the infectivity of the inoculum, under different temperatures, was investigated. Experiment 1. Effect of addition of Tris-HCl buffer on sporulation of AMF. Seeds of Panicum miliaceum L. (50 per pot) were disinfected with Sodium Hypochlorite (0.05% /10 min) and washed with distilled water before being planted. The substrate used was washed river sand (pHH2O 7.1) and vermiculite of medium granulation (1:1 v/v). Both were autoclaved (30 min./1 atm/120ºC), in two consecutive days, and used 15 days after sterilized. Spores of Glomus etunicatum Becker and Gerd. (UFPE 06), Gigaspora albida Schenck and Smith (UFPE 01), Scutellospora heterogama (Nicol. and Gerd.) Walker and Sanders (UFPE 19) and Acaulospora longula Spain and Schenck (UFPE 21) were inoculated as suspensions (50 spores of each AMF), in plastic pots (400 mL) with 300 g of substrate, below the host seeds. The pots were maintained in a greenhouse for 85 days; temperature (Tmin. 22.81ºC; Tmax. 32.39ºC), humidity (RUmin. 45.62%; RUmax. 81.13 %) and light were not con...

Optimization of the production of mycorrhizal inoculum on substrate with organic fertilizer

“…Thus, from the tested isolates, only A. longula presented such characteristics, when multiplied in substrate with vermicompost. It is important to emphasize that the sporulation of this fungus was lower than that registered in other studies ( Silva et al , 2005 ; Silva et al , 2007 ; Zambolim et al , 1992 ) but the fungus was infective and effective in favoring growth of corn.…”

“…A promising system is the use of sand and vermiculite, which favors the production of glomerospores with increased infectivity ( Silva et al , 2005 ; Silva et al , 2007 ). However, the addition of nutrient solution to the substrate is a barrier to the system because it is not simple and economical ( Gianinazzi and Vosátka, 2004 ).…”

Water availability and formation of propagules of arbuscular mycorrhizal fungi associated with sorghum

“…In contrast, G. albida and S. heterogama, which had greater sporulation than C. etunicatum, showed reduced infectivity potential. The greater potential for infectivity of C. etunicatum may be related to the storage of the inoculum under low temperature (4 C), since Silva et al (2007) showed that the maintenance of inoculum of C. etunicatum for 120 days at 5 C increased its infectivity, but in G. albida this does not occur.…”

Insight into the Role of Arbuscular Mycorrhizal Fungi in Sustainable Agriculture

“…In addition, organic fertilization enhances AM fungal association and formation of AM fungal propagules in the soil (Gryndler et al 2005 ;Gaur and Adholeya 2005 ), thereby improving soil quality. Though organic fertilizers generally have a positive effect on crops as evidenced by enhanced growth and accumulation of nutrients (Silva et al 2007 ;Sharif et al 2012 ), results of some studies are found to be opposite (Martin et al 2002 ;Elorrieta et al 2003 ). A consortium of seven AM fungi isolated from the soils of coffee ( Coffea arabica ) plantations with different fertilizer inputs (low, intermediate and high) was examined for their growth-promoting ability in coffee both under nursery and fi eld conditions.…”