63ª Reunião Anual da SBPC

E. Ciências Agrárias - 1. Agronomia - 3. Fitossanidade

Gas exchanges in Phaseolus vulgaris infected by Colletotrichum lindemuthianum

Jamille de melo Pinho 1 Odyone Nascimento da Silva 1 Izabelle Pereira Andrade 1 Allan Klynger da Silva Lobato 1 Eldenira Barbosa Uchôa 1 Argemiro Pereira Martins Filho 1

1. Núcleo de Pesquisa Vegetal Básica e Aplicada, Universidade Federal Rural da Amazônia

INTRODUÇÃO:

The species Phaseolus vulgaris L. is known as common bean and it is considered as one of the most important legume in the world, because grain represents a protein and carbohydrate source.Anthracnose is a disease promoted by the pathogen Colletotrichum lindemuthianum that attack Phaseolus vulgaris plants. This fungus under favorable conditions as high temperature and humidity can infect common bean crop in all growth stages. Objective of this present study was to evaluate infection effects promoted by Colletotrichum lindemuthianum pathogen (race 2047) on stomatal conductance and transpiration rate in Phaseolus vulgaris plants (cv. Mexico 222).

METODOLOGIA:

The study was conducted in greenhouse and growth chamber conditions located in Núcleo de Pesquisa Aplicada à Agricultura (Nupagri), Universidade Estadual de Maringá (UEM).Seeds of Phaseolus vulgaris Mexico 222 cultivar, which presents a determined growth, it was obtained from the Nupagri seed bank. Pathogen employed to infect the plants was the fungus Colletotrichum lindemuthianum race 2047, and cultivar Mexico 222 was to this fungus. Plants were grown in greenhouse conditions controlled by the local weather minimum/maximum temperature was 34.8/13.5ºC and relative humidity was 55/81%, respectively, during the experimental period. Inoculum obtained from Nupagri was transferred culture tubes that contained growing medium and immature pod beans. The experimental design employed was completely randomized in factorial, with 2 factors (condition and evaluation period). The two conditions (control and inoculated) were combined with three evaluation periods (4, 8 and 12th day after inoculation). The experiment was composed of six replicates, and thirty six experimental units (1 plant in each unit).In this study were evaluated stomatal conductance and transpiration rate, being measured in well expanded trifoliolate leaves 3rd, located at the middle of the main branch at the stage V4. Data were analyzed employing a variance analysis, and using Tukey test at 5% level of probability. Standard errors were also calculated in all treatments evaluated.

RESULTADOS:

Stomatal conductance was influenced by the pathogen infection, because inoculated plants showed lower values in all evaluated dates, compared with uninfected plants. A significant reduction of 78.9% was showed for the 12th day after pathogen inoculation. Transpiration rate in infected plants was lower in all the evaluated periods when control and infected plants were compared. Inoculated plants showed reductions of 12.7, 23.2, and 67.7% at the 4, 8, and 12th day after the pathogen inoculation, respectively, but just transpiration rate had presented significant differences at the 8th and 12th day. The decrease in stomatal conductance of inoculated plants is a consequence in stomatal damage induced by the pathogen decreasing gas exchange. Disease progress causes stomatal conductance decrease. Our results suggest that the susceptible plants infected do not close stomatal during of the infection process (significant reduction was found only at the 12th day after inoculation). Similarly, transpiration rate was reduced in plants under inoculation, and this fact indicates that water transported from root to leaves was affected by the pathogen infection. Transpiration is a physiologic process characterized by differences in vapor pressure in the sub-stomatal cavity and atmosphere providing a cooler effect to leaves (leaf thermoregulation), but also transporting compounds from root to leaves.

CONCLUSÃO:

Stomatal conductance and transpiration rate in Phaseolus vulgaris plants were reduced when subjected to pathogen infection Colletotrichum lindemuthianum race 2047.

Palavras-chave: Colletotrichum lindemuthianum, stomatal conductance, transpiration.