63ª Reunião Anual da SBPC

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

Modifications in gas exchange of Phaseolus vulgaris infected by pathogen Colletotrichum lindemutianum.

Railan do Nascimento Ferreira 1 Daniele Viana da Costa 1 Emilly dos Santos Pereira 1 Gustavo Antonio Ruffeil Alves 1 Cândido Ferreira de Oliveira Neto 1 Allan Klynger da Silva Lobato 1

1. Núcleo de Pesquisa Vegetal Básica - UFRA

INTRODUÇÃO:

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. In addition, this pathogen causes morphological, physiological and biochemical alterations that has been previously described in Phaseolus vulgaris, such as the significant decrease in photosynthetic pigments, photosynthesis rate, and consequent yield reduction. The aim of this study was to evaluate infection effects promoted by pathogen Colletotrichum lindemuthianum (race 2047) in photosynthesis rate and efficiency of the use of water photosynthetic in plants Phaseolus vulgaris.

METODOLOGIA:

The study was conducted in greenhouse and growth chamber conditions located in Núcleo de Pesquisa Aplicada à Agricultura (Nupagri). Photosynthesis rate and photosynthetic water use efficiency were evaluated in well expanded trifoliolate leaves 3rd, located at the middle of the main branch at the stage V4. So, the plants presented three trifoliolate leaves during V4 stage and photosynthetic water use efficiency was estimated according to Osmond et al. (1980). Radiation level and temperature in the chamber were previously evaluated to this crop, and adjusted to 1100 µmol m-2 s-1 and 32ºC, respectively. Gas exchange parameters were evaluated between 09:00 and 12:00 h. 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:

Photosynthetic rate was reduced by the infection of Colletotrichum lindemuthianum pathogen showing significant reductions of 22, 49.9, and 77.3% at the 4, 8 and 12th after inoculation, respectively. Photosynthetic water use efficiency presented similar behavior as photosynthesis rate in control and inoculated plants. But just it is showed significant differences between control and infected plants at the 8th and 12th day, when compared to 4th day after inoculation. Photosynthetic rate in inoculated plants were reduced in all the evaluated periods indicating that Colletotrichum lindemuthianum pathogen caused strong negative effects over influence under photosynthesis rate and photosynthetic pigment. Pigment reduction and consequent lower capacity to absorb light promotes decrease in photosynthesis rate. Low photosynthesis on leaves is the reason of the lower yield in infected plants by this fungus. Reduction in photosynthetic water use efficiency of infected plants is a consequence of the fungus over gas exchanges because this parameter dependents on photosynthesis and transpiration.

CONCLUSÃO:

Colletotrichum lindemuthianum pathogen causes strong negative effect on photosynthesis rate and efficiency of the use of water photosynthetic in Phaseolus vulgaris plants.

Palavras-chave: Colletotrichum Lindemuthianum, Common Bean, Photosynthesis.