Maize development and grain quality are differentially affected by mycorrhizal fungi and a growth-promoting pseudomonad in the field

Abstract

Arbuscular mycorrhizal (AM) fungi and plant growth-promoting bacteria (PGPB) can increase the growth and yield of major crops, and improve the quality of fruits and leaves. However, little is known about their impact on seed composition. Plants were inoculated with AM fungi and/or the bacterial strain Pseudomonas fluorescens Pf4 and harvested after 7 months of growth in open-field conditions. Plant growth parameters were measured (biomass, length and circumference of spikes, number of grains per cob, grain yield, and grain size) and protein, lipid, and starch content in grains were determined. Plant growth and yield were increased by inoculation with the microorganisms. Moreover, spikes and grains of inoculated plants were bigger than those produced by uninoculated plants. Regarding grain composition, the bacterial strain increased grain starch content, especially the digestible components, whereas AM fungi-enhanced protein, especially zein, content. Plant inoculation with the fluorescent pseudomonad and mycorrhizal fungi resulted in additive effects on grain composition. Overall, results showed that the bacterial strain and the AM fungi promoted maize growth cultivated in field conditions and differentially affected the grain nutritional content. Consequently, targeted plant inoculation with beneficial microorganisms can lead to commodities fulfilling consumer and industrial requirements.

Contrasting effects of cover crops on ‘hot spot’ arbuscular mycorrhizal fungal communities in organic tomato

“…Presently, the role of AMF in influencing soil fertility, crop productivity, yield quality and protection against environmental stresses is widely acknowledged (van der Heijden et al 1998;Smith and Read 2008;Giovannetti et al 2012;Berta et al 2013). AMF contribution to crop growth and productivity can be influenced by both interspecific and intraspecific differences (Munkvold et al 2004;Vogelsang et al 2006).…”

Impact of Mycorrhizal Fungi and Rhizosphere Microorganisms on Maize Grain Yield and Chemical Composition

“…M fungi from fertilized soil produced fewer hyphae and arbuscules and consequently supplied their host with fewer inorganic nutrients from the soil (Johnson, 1993). Concerning the mycorrhizal colonization of inoculated plants of this trial, F (87.8%) was lower than the expected based on some similar available studies in field conditions (Berta et al, 2014). The significant, but not remarkable differences between the rates of root colonization in inoculated plants respect to uninoculated ones may be explicated considering the difficulty the AM inoculum has to face in soil colonization.…”

“…As a matter of fact, mycorrhizal index (F%) values registered in uninoculated maize were very high (80.3%), when compared with related studies. The AM colonization of uninoculated maize produced under field conditions varied according to different Authors: 39.7% in maize as following crop after Trifolium alexandrinum (Pellegrino et al, 2011), 25.1-61.2% in two consecutive years (Sousa et al, 2012), 45% (Cheeke et al, 2013) and 55.3% (Berta et al, 2014). Autochthonous AM fungi can colonize roots of most plant species, including maize (Smith and Read, 2008), but it was clearly demonstrated that the soils exposed to intensive cultivation have extremely low number of indigenous AM fungal propagules (Li and Zhao, 2005;Subramanian et al, 2009).…”

“…Responses of plant to exotic inocula are supposed to depend on some factors including: physical and chemical soil characteristics (Davis et al, 1983;George, 2000), native mycorrhizal density, host plant (Pellegrino et al, 2011). Moreover, the effect of inocula on seed characteristics of major crops has been little focused (Berta et al, 2014). More efforts are needed to clarify what strains of fungi, PGPR as well as their combination are most effective in plant helping and benefit and to evaluate what is the effectiveness of co-inoculation in a multi-stressed natural environment for commercialization of microbial inocula (Nadeem et al, 2014).…”

Borderline Products between Bio-fertilizers/ Bio-effectors and Plant Protectants: The Role of Microbial Consortia

“…Application of a consortium of AMF and the plant growth-promoting rhizobacteria (PGPR) was studied by Mäder et al [47] and found to positively affect crop yield, grain, soil quality and nutrient uptake of the staple food crop wheat (Triticum aestivum (L.)) in a rotation with either rice (Oriza sativa (L.)) or black gram (Vigna mungo (L.) Hepper). Recently, Berta et al [48] have shown that the inoculation with MC containing bacteria and AMF promote the growth of maize cultivated in field conditions and differentially affect the grain nutritional content.…”