Dispensa e dinâmica populacional do agente de biocontrole Pseudomonas putida no filoplano de tomateiro

• Autor(a) principal: Ferraz, Hélvio Gledson Maciel
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4369
• topic: Tomate; Doenças; Controle biológico; Dinâmica populacional; Pseudomonas putida; Tomato; Diseases; Biological control; Populational tendencies; Pseudomonas putida; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA

In most experiments dealing with biological control of plant diseases, plant growth-promoting rhizobacteria (PGPR) are delivered by seed microbiolization while bacterial phylloplane residents are delivered by spraying. In this work aimed to test several procedures for delivering the biocontrol agent Pseudomonas putida to tomato plants, as well as to study populational tendencies of the biocontrol agent in plant surfaces and to make attempts to establish correlations among populational tendencies and efficiency of biological control. The bacterium Pseudomonas putida (isolate UFV- 0073), autochthonous in tomato phylloplane, was previously selected for the biocontrol of tomato aerial part diseases. Four deliver modes were tested, as follow: 1- seed microbiolization (OD540 = 0,3) followed by planting; 2 - spraying tomato phylloplane with bacterial live propagules (OD540 = 0,3); 3 microbiolization and spraying seedlings with the antagonist (treatments 1 and 2) and 4 - spraying tomato phylloplane with the supernate obtained from bacterial culture (OD540 = 1.0). Results indicated that for the pathosystem tomato - Xanthomonas campestris pv. vesicatoria the most efficient deliver mode was to spray tomato phylloplane with propagule suspension of the antagonist while for its counterpart tomato- Pseudomonas syringae pv. tomato pathosystem, the best deliver modes were to spray the phylloplane with culture supernates and seed microbiolization along with phylloplane spray with a propagule suspension. In order to study populational tendencies for the biocontrol agent UFV-0073 in tomato phylloplane, a semi-selective culture medium was developed and tested based on the constitutive multiple resistance to antibiotics exhibited by the aforementioned isolate of P. putida. Under greenhouse conditions, measurement of population tendencies as a function of time indicated a population decrease in the sense that at day 0, the population was estimated as 8,92 x 107 CFU/g of leaf tissue and in day 5 this population went down to 4,13 x 105 CFU/g of leaf tissue, what means a population 215 times smaller that the original one. On the other hand, under field conditions, the populational tendency did decrease but in a slower rate and presented a tendency to equilibrium, with up and down population peaks in terms of recovered bacteria. So, at 0 day , the population was estimated as being 4,62 x 106 CFU/g leaf fresh weight and nine days after deliver it was 9,91 x 105 UFC/g, what means five times smaller than the population at 0 day. Last but not least, it was established a correlation between populational tendencies of the P. putida in the phylloplane and biocontrol of tomato bacterial speck (P. syringae pv. tomato), when results indicated that the biocontrol was effective up to the fifth day after deliver. This work provides a better understanding about the best deliver mode of P. putida while biocontrol agent for tomato diseases in the aerial parts as well as about time intervals for delivering the biocontrol agent under investigation.