Use of overburden waste for London plane (Platanus × acerifolia) growth: the role of plant growth promoting microbial consortia

Abstract

(1)Overburden waste dumps represent a huge threat to environmental quality. The reduction of their negative impact can be achieved by vegetation cover establishment. Usually, this action is complicated due to site-specific characteristics, such as nutrient deficiency, elevated metal concentration, low pH value, lack of moisture and lack of organic matter. Establishment of vegetation can be facilitated by inoculation with plant growth promoting bacteria (PGPB) which improve the physicochemical and biological properties of degraded substrates and make them more hospitable for plants. In this study we selected several strains based on the ability to produce ammonia, indole-3-acetic acid, siderophores and lytic enzymes, and to solubilize inorganic phosphates. This selection resulted in microbial consortia consisting of Serratia liquefaciens Z-I ARV, Ensifer adhaerens 10_ ARV, Bacillus amyloliquefaciens D5 ARV and Pseudomonas putida P1 ARV. The effects of PGPB consortia on one-year-old London plane (Platanus × acerifolia [Aiton] Willd.) seedlings replanted into overburden waste from Kolubara Mine Basin were examined. After seven months, inoculated seedlings were 32% higher with 45% wider root collar diameter and over 80% higher total dry biomass compared to uninoculated seedlings grown in Kolubara's overburden. Inoculation resulted in higher amounts of total soluble proteins, higher chlorophyll and epidermal flavonoids content and higher total antioxidative capacity in the leaves. This study represents a successful search for effective PGPB strains and shows that microbial consortia have an important role in enhancing the growth of seedlings in nutrient deficient and degraded substrates such as overburden waste from open-pit coal mines. Positive response of London plane seedlings suggest that inoculation may help widening the opus of species for reforestation of post mining areas and speed up natural succession processes and recovery of degraded landscapes.

Biomagnetic Priming—Possible Strategy to Revitalize Old Mustard Seeds

“…In this study, we investigated the possibility of using B. amyloliquefaciens D5 ARV and SMF in priming of old white mustard seed. Karličić et al [2017] had shown that B. amyloliquefaciens D5 ARV used in the current research has the potential for application in sustainable cultivation of plants, aimed to alleviate environmental stress. On the other hand, beneficial effects of SMF on plant growth are well‐documented and Ćirković et al [2017] showed that application of SMF increased germination speed of wheat.…”

Serratia strains isolated from the rhizosphere of raulí ( Nothofagus alpina ) in volcanic soils harbour PGPR mechanisms and promote raulí plantlet growth

“…The ability of rhizobacteria to produce phytohormones has long been believed to be a major factor affecting plant root growth; specifically, it is thought that these phytohormones allow the plant to extract nutrients from a greater volume of soil (Egamberdieva et al, 2017). Additionally, other studies have shown that IAA produced by PGPR affects tree root morphology (George et al, 2013) and metabolic processes such as photosynthesis, biosynthesis of various metabolites, and resistance to stressful conditions modulated by auxins (Egamberdieva et al, 2017;Karličić et al, 2017). Accordingly, IAA indirectly increases water and nutrient supplies leading to higher root exudation and biomass production in forest species (Egamberdieva et al, 2017;Karličić et al, 2017).…”

“…Additionally, other studies have shown that IAA produced by PGPR affects tree root morphology (George et al, 2013) and metabolic processes such as photosynthesis, biosynthesis of various metabolites, and resistance to stressful conditions modulated by auxins (Egamberdieva et al, 2017;Karličić et al, 2017). Accordingly, IAA indirectly increases water and nutrient supplies leading to higher root exudation and biomass production in forest species (Egamberdieva et al, 2017;Karličić et al, 2017). Furthermore, it has been shown that IAA triggers the activation of the central energy metabolism of Escherichia coli cells (Bianco et al, 2006b) and is also able to enhance protection against various abiotic stresses such as UV and low pH (Bianco et al, 2006a).…”

“…The bacterial cells pellets were re-suspended in saline solution (0.85%) and adjusted to have a final concentration of 10 8 CFU mL −1 . For making the bacterial mixtures, equal cell densities (10 8 CFU mL −1 ) of all individual cultures were mixed together in a 250 mL sterilized flask (Karličić et al, 2017). The control was inoculated with saline solution (0.85%) without bacteria.…”

“…Plantlets were subjected to growth evaluation 8 months after the trial started. Plant parameters evaluated were: Biomass (total dry matter, root and shoot dry matter), plant height, root collar diameter (RCD), relative chlorophyll content (RCC), and nitrogen content (Karličić et al, 2017).…”