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| Author(s): |
Leonardo Souza de Andrade
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2023-09-05 |
| Examining board members: |
Sara Adrián López de Andrade;
Fernando César Bachiega Zambrosi;
Matheus Aparecido Pereira Cipriano
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| Advisor: | Sara Adrián López de Andrade |
| Abstract | |
Phosphorus (P) is a finite resource that often limits agricultural production since most of this element is in forms unavailable to plants. Organic P (Po) can constitute up to 50% of the total P in natural soils and cannot be directly absorbed by plant roots. Po needs to undergo a mineralization process carried out by phosphatase enzymes (APases) or phytases, which are capable of hydrolyzing P from phytate molecules, and which can be secreted by the plant roots themselves and/or by the soil microbiota constituted of bacteria, fungi, and other microorganisms. Arbuscular mycorrhizal fungi (AMFs) are obligate biotrophic organisms which associates with plant roots and play an important role in the P nutrition of host plants while receiving photoassimilates that ensure the symbiotic relationship. In this work, we aimed to evaluate the ability of two eucalyptus species to use P from organic or poorly soluble sources, as well as to evaluate the contribution of symbiosis with AMF Rhizophagus intraradices in the acquisition of P from these sources. Two experiments were carried out concomitantly in a 7 × 2 factorial scheme, with ten replications, totaling 140 experimental plots each. Experiment 1 had as study plant Eucalyptus globulus (Gl) and experiment 2 plants of E. grandis (Gr). The factors under study were: 7 sources of P: glucose-6-phosphate (G); phytate (F); torula yeast RNA (R); ATP (A); Pseudomonas putida necromass (N); potassium phosphate (C) and iron phosphate (Fe) and inoculation (M) or not (NM) of AMF. For all P sources, P concentration was 0.1 mM. The plants were grown for 12 weeks and daily irrigated. We evaluated the production of shoot and root biomass, root phytase and phosphatase activity (rAPase) besides external mycelium phosphatase activity (mAPase), outer mycelium length, plants P concentration and content, as well as plants P uptake efficiency (PUpE) and use (PUE). We observed that E. globulus plants were more efficient in P use and absorption than E. grandis plants. AMF inoculation influenced the increase of PUpE and P content of host plants in general, in addition to increasing the phytase and APase activity of plants under some P sources, such as phytate. Plants which received phytate and iron phosphate accumulated less P content and biomass, despite intense APase activity, indicating plant response to low P concentration and the recalcitrance of these two P sources. However, the sources of G6P and potassium phosphate were more susceptible to be used by eucalyptus plants. Bacterial necromass had a great influence on the increase in the extension of the outer mycelium, as well as the APase of the mycelium, possibly due to the large amount of nutrients other than P in this Po source, capable of contributing to the nutritional status of plants and in the recruitment of microorganisms with APases to the hyphosphere. We conclude that plant species differ in their ability to utilize different P sources, and this is related to their root enzymatic activities; AMF plays an important role in the P acquisition from organic sources to the associated eucalyptus plants, improving plants PUpE and that bacterial necromass can provide elements such as N, P and C influencing mycelium and possibly, associated mycelium microorganisms activities, contributing positively to the mAPase and to the growth of the AMF mycelium associated with eucalyptus plants (AU) | |
| FAPESP's process: | 21/05815-9 - Potential for mobilization and use of phosphorus from organic sources in Eucalyptus grandis and E. globulus: arbuscular mycorrhizal influence |
| Grantee: | Leonardo Souza de Andrade |
| Support Opportunities: | Scholarships in Brazil - Master |