Controlled-release fertilizers combined with Pseudomonas fluorescens rhizobacteria inoculum improve growth in Pinus halepensis seedlings

Abstract

© iForest -Biogeosciences and Forestry IntroductionPinus halepensis is one of the most common tree species in the Mediterranean and is also frequently used for reforestation purposes (Maestre & Cortina 2004). Several studies have been carried out with the aim of improving the quality of P. halepensis seedlings obtained from nurseries (Caravaca et al. 2005). The application of chemical fertilizer treatments to forest seedlings in nurseries is the most common cultivation practice. However, it has been established that soil amendments, including ectomycorrhizal fungi and plant growth-promoting rhizobacteria (PGPR), increase plant survival and seedling quality, especially in soils with low microbial activity (Chanway 1997, Probanza et al. 2001.Pseudomonas fluorescens has several characteristics of an effective PGPR and may function as a plant growth stimulator that efficiently promotes seed germination, accelerates growth in the early stages, induces root initiation, enhances the formation of roots and root hairs, facilitates root regeneration and helps to control pathogens in certain forest species. P. fluorescens is easily cultivated in vitro and colonizes a wide range of ecological niches, including the rhizospheres of plants (Bolton et al. 1993); additionally, P. fluorescens genomes are highly diverse (Silby et al. 2009), which likely increases the survival capacity of this microorganism. P. fluorescens improves plant growth by producing phytohormones, such as auxins (IAA), gibberellins and cytokinins, as well as specific amino acids. Furthermore, these bacteria have a high capacity for phosphorus solubilization and are able to produce siderophores (Matthijs et al. 2007).Despite the well-known positive effects of P. fluorescens on plant survival (Silby et al. 2009), only a small number of studies have examined its influence on the growth of forest species (Ouahmane et al. 2009, LucasGarcía et al. 2004). Some of these effects have been observed specifically in P. halepensis inoculated with P. fluorescens Aur6 (Rincón et al. 2008). Recently, we showed that inoculation of Aleppo pine with P. fluorescens CECT 844 improved both its vegetative growth and N uptake (Dominguez et al. 2012).It has been demonstrated that the frequent use of chemical fertilizers in nurseries leads to soil contamination, as chemical fertilizers are not completely assimilated by the seedlings. Furthermore, the industrial practices necessary for the chemical synthesis of compounds containing inorganic nitrogen require the use of contaminating petroleum products, high temperatures and high pressures. Considering these issues, the use of natural, "environmentally friendly" microbial inoculums, such as PGPR rhizobacteria or mycorrhizal fungi, as alternative fertilizers can be considered as a potential future solution. These microorganisms are also beneficial for the maintenance of pre-existing soil microflora, contributing to the conservation of biodiversity. The amended soil eventually enhances the vegetative vigor and the morphophysiological at...

Soil Inoculation With Beneficial Microbes Buffers Negative Drought Effects on Biomass, Nutrients, and Water Relations of Common Myrtle

“…However, under water deficit stress, reduced water uptake and curtailed transpiration result in a decrease in leaf Ca content ( Maksimović et al, 2003 ). In line with the findings of Dominguez-Nuñez et al (2014) on Pinus halepensis and Meddich et al (2015) on Phoenix dactylifera , we observed AMF- and PGPR-induced increases in root and foliar Ca contents of myrtle seedlings ( Figure 5 ). Apart from increases in Ca availability resulting from the exploitation of a larger soil volume through AMF hyphae and accelerated mineral weathering linked to PGPR secretions, the positive inoculation effect on Ca levels in myrtle seedlings may in part be due to increases in stomatal conductance and transpiration given the role of xylem sap flow in Ca mobility ( Ruiz-Lozano et al, 1995 ; Wu and Xia, 2006 ; Garg and Bhandari, 2016 ; Azizi et al, 2021 ).…”

Inoculation of Pinus taeda Seedlings with Plant Growth-promoting Rhizobacteria

“…Previous research has been carried with the same bacterium, but different plant species. Dominguez-Nuñez et al (2015) noticed that Pinus halepensis seedlings inoculated with Pseudomonas fluorescens had a 26% wider root-colar diameter. Shoot dry weight was also greater in inoculated plants, but height and root dry weight were not influenced by inoculation.…”

Efecto de rizobacterias y dosis reducidas de fertilizantes sintéticos sobre la expresión morfo‑productiva de tomate en invernadero

“…Estudios sobre la aplicación de rizobacterias y fertilizantes sintéticos han reportado un incremento en el crecimiento de las plantas, debido a una mayor capacidad de absorción de los nutrimentos (Dominguez-Nuñez et al, 2015;Paungfoo-Lonhienne et al, 2019), promovida principalmente por el aumento de las poblaciones rizobacterianas (Tahir et al, 2018). Al respecto Naseri y Mirzaei (2010), reportan que la aplicación de Azotobacter sp.…”