We have isolated bacteria from the rhizosphere of two perennial crop plants (Bactris gasipaes and Theobroma grandiflorum) growing on the SHIFT experimental site near Manaus

GASPAROTTO, L.

MARINO, W.

MARSCHNER, P.

English

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Gerrnan-Brazilian Workshop on Neotropical Ecosystems - Achievements and Prospects of Cooperative ResearchHamburg, Septernber 3-8, 2000Recuperation of Degraded Areas - Summaries of Lectures, Session 5Phosphate Solubilizing Bacteria from the Rhizosphere of Theobroma grandiflorum (Willd. exSpreng.) Schum. and Bactris gasipaes H.B.K.: Potential for Plant Growth PromotionMarino, w,', Marschner, p.1 and Gasparotto, L.21 Institut für Angewandte Botanik, Universitat Hamburg,Hamburg, Germany2 EMBRAPA Amazônia Ocidental, Manaus, BrazilDespite high total phosphorus (P) concentrations in manytropical soils P deficiency may limit plant growth. Pavailability is low due to formation of insoluble P saltsand/or sorption of P to Fel AI oxides and hydroxides as welIas to the organic matter. Productivity of crop plants may beincreased by inoculation with mycorrhiza or P solubilizingmicroorganisms. While the use of mycorrhizal fungi iswidespread inoculation P solubilising microorganisms isstilI uncommon. However these microorganisms may havea potential to increase plant growth particularly incombination with mycorrhizal fungi. Plant growthpromotion is often increased not only by P solubilization butalso N2 fixation and production of phytohormones.We have isolated bacteria from the rhizosphere of twoperennial crop plants (Bactris gasipaes and Theobromagrandiflorum) growing on the SHIFT experimental site nearManaus. More than 70% of the isolates were capable togrow in the presence of Fe and AI phosphate as a sole Psource. The two bacteria chosen for further studies wereidentified as BacilIus sp. and Gordonia sp. An in vitro studyshowed that the P solubilisation by the organisms isprobably due to the excretion of organic acids. Organicacids increase P solubilization by chelation of Fe and AI andby displacement of P from the binding sites. However mostof the P solubilized was taken up by the celIs and the Pconcentration in the medi um remained low.Results of green house experiments with tomato wereambiguous. In one experiment both organisms increasedplant growth on Fel AI phosphates compared to the notinoculated control while this was not the case in the secondexperiment. Possible explanations for these conflictingresults are differences in inoculum survival and Iightintensity. It is planned to repeat the experiments and toinc1ude mycorrhizal fungi.Characteristics of Sustainable Polyculture Production Systems on Terra FirmeLieberei n.', Gasparotto L.2, Preisinger H.I and Schroth c.'1 Universitat Hamburg, Hamburg, Germany2 CPAA, Manaus, BrazilStable systems in tropical ram forest areas must possessregulatory factors similar to those of the primary forest:closed mineral recycling systems and efficient mechanismsfor water and energy distribution. These features can not beachieved by a single species, but depend on a combinationof species with various suitable, synergistic properties inroot and canopy formation as welI as in biochemical andbiophysical factors adapted to the site.The combination of soil science, forestry, agronomy andbiology alIowed an analytical comparison of variousexperimental mixed culture systems. From these studies, adescriptor system was developed which alIows tounderstand the contribution of each plant species to nutrientcyc1ing, water distribution, litter formation, overalI biomassproduction and crop production. This knowledge alIows tocombine plants so that their properties interact to form asystem, which minimizes mineral losses and whichregulates air humidity and water distribution and thus leadsto stable crop production.The artificial planting systems are designed as productionsystems for smalI holders. They must deliver food crops asearly as possible to maintain survival on a subsistence basisand they must rapidly produce cash crops in order toprovide family income and to pay for various managementsteps. AlI systems undergo changes in time and space andconsist of an instalIation phase, where only some annualproduction of maize, cassava, beans are available, folIowedby a transition phase with production of papaya, maracuja,Marino. W, Marschner; P. and Gasparotto, L.: Phosphate Solubilizing Bacteria from lhe Rhizosphere of Theobroma grandiflorum (Willd. ex Spreng.) Schum.and Bactris gasipaes H.B.K.: Potential for Plant Growth PromotionLieberei R.. Gasparotto L., Preisinger H. and Schroth C .. Characteristics of Sustainable Polyculture Production Systems 011 Terra Firme190

Phosphate solubilizing bacteria from the rhizosphere of Theobroma grandiflorum (Willd. ex Spreng.) Schum. and Bactris gasipaes H.B.K.: potential for plant growth promotion.

http://www.alice.cnptia.embrapa.br/bitstream/doc/673203/1/Neotropicalpag.190.pdf

Phosphate solubilizing bacteria from the rhizosphere of Theobroma grandiflorum (Willd. ex Spreng.) Schum. and Bactris gasipaes H.B.K.: potential for plant growth promotion.

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