Monda, Hiarhi (2016) BIO-EFFECTORS: REDUCING IMPACT OF MINERAL FERTILIZERS BY APPLICATION OF BIOLOGICAL AND NATURAL PRODUCTS. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Lingua: English
Title: BIO-EFFECTORS: REDUCING IMPACT OF MINERAL FERTILIZERS BY APPLICATION OF BIOLOGICAL AND NATURAL PRODUCTS
Creators:
CreatorsEmail
Monda, Hiarhihiarhi.monda@yahoo.it
Date: 31 March 2016
Number of Pages: 110
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Scuola di dottorato: Scienze agrarie e agro-alimentari
Dottorato: Valorizzazione e gestione delle risorse agro-forestali
Ciclo di dottorato: 28
Coordinatore del Corso di dottorato:
nomeemail
D'Urso, Guidodurso@unina.it
Tutor:
nomeemail
Spaccini, RiccardoUNSPECIFIED
Date: 31 March 2016
Number of Pages: 110
Uncontrolled Keywords: Compost water extracts; Humic substances; Bioactivity; Seedling growth; NMR 13CPMAS; IR DRIFT; TGA ;PSB; Arbuscular mycorrhizal fungi; Pseudomonas proradix; Bacillus amyloliquefaciens; Humic acids; Bioactivity; Microbial ecology; PGPR; PLFA; DGGE
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/13 - Chimica agraria
Date Deposited: 14 Apr 2016 11:59
Last Modified: 19 May 2018 01:00
URI: http://www.fedoa.unina.it/id/eprint/10903
DOI: 10.6093/UNINA/FEDOA/10903

Abstract

Sustainability in natural ecosystems is dependent on chemical and biological balance in the soil which is mainly governed by the cross-interaction of microbial communities with organic matter and plant roots. The development of efficient tools to manage these key factors could offer to modern agriculture a way to improve productivity and reduce the reliance on chemical fertilizers. The research described in this thesis is focused on the increase of efficiency of the most promising bio-effectors (i.e. plant growth promoting microorganisms PGPMs) and active natural compounds derived from recycled products with the final goal to contribute to the ecological intensification of agriculture, by developing a viable alternative to mineral fertilisers. Firstly, we started with a series of laboratory extractions of organic matter from recycled products and evaluated their bioactivity on maize seeds germination and seedlings growth in preliminary hydroponic experiments. Investigation on the chemical and molecular characteristics of water-extractable organic matter (WEOMs) and humic acids (HAs) from different on-farm composts were carried out with a primary focus on illuminating the relationship with plant growth promoting activity. A greenhouse pot experiment was carried out using maize plants treated with different phosphate solubilising microorganisms (Trichoderma harzianum and Bacillus amyloliquefaciens) in a phosphorus deficient soils, when different type of P-fertilizers were used ( mineral fertilizers: triple super phosphate and rock phosphate vs organic amendments: composted cow/buffalo manure and composted horse manure). Here we investigated the ability of each bio-effectors to promote maize plant growth and nutrient uptake and evaluated the effects on the microbial community through PLFA and NLFA analysis. Mineral fertilizers produced the best performances but evidence is provided that the addition of composted manure and microorganisms positively affected indigenous mycorrhizal fungi population and plant fitness when compared to control. However, None of the known PGPM per se has the potential to fulfill the requirements of providing a feasible alternative to mineral fertilizers. Therefore, relying on previously promising results, we decided to perform a greenhouse experiment in which different combination of bio-effectors were tested to verify the potential synergistic effect towards the increasing efficiency of plant nutrient uptake. Two phosphate solubilizing bacteria, Pseudomonas proradix and Bacillus amyloliquefaciens, a mixture of two arbuscular mycorrhizal fungi (AMF), Glomus mosseae and Rhizophagus irregularis, and a humic acid (HA) extracted from compost were combined in order to study the best combination when composted cow/buffalo manure were used as a P-source. Best results were obtained with the combination of phosphate solubilizing microorganisms, AMF and humic acids, evidencing a clear synergistic effects. Furthermore, the analysis of PLFA biomarkers and DGGE molecular fingerprint provided an insight into microbial communities changes and composition, revealing the increased development of AMF and the simultaneous depletion of saprophytic fungi when plants were co-inoculated with B. amyloliquefaciens and HA. The outcomes achieved by this dissertation provide valuable information on the dynamics of the multi-partite interactions involved in the rhizosphere and highlight the role of humic substances in sustaining microbial activity and possibly driving plant microbes cross-communication. The combination of different bio-effectors is thus confirmed as a potential biotechnological tool to overcome mineral fertilization systems.

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