HERBICIDE DOES NOT IMPACT DIAZOTROPHIC BACTERIA-PROMOTING GROWTH OF RED RICE PLANTS

Resumo

Background Diazotrophs bacteria that promote plant growth have been studied as a strategy to increase the productivity of rice cultivation. Herbicides are used to prevent weed infestations.

Objective The evaluation of herbicides effect on diazotrophic bacteria strain associated with the growth of Red Small rice.

Methods Three experiments were conducted: I - in vitro growth of bacterias (Azospirillum brasilense strain 245 and Herbaspirillum seropedicae strains 26H, Z67, Z94, ZA25 and ZAL95); II - germination of red rice seeds; III - growth and production of red rice plants inoculated with diazotrophic bacteria and treated with quinclorac, penoxsulam and cyhalofop-butyl herbicides.

Results I - All bacterial strain growth was inhibited under the highest herbicide doses, except strain 245. II – The number of roots reduced upon increasing herbicide concentration for strain 245. III - The dry mass increased in plants inoculated with strains 245 and ZA25. Besides, strains 245, 26H and ZAL95 provided better performance for dry root mass. At 60 days, the same behavior of the first evaluation was observed. At final cycle, increases in fresh and dry root mass and dry mass of grains were evidenced, especially on rice inoculated with strains 245 and ZA25.

Conclusions The herbicides do not impact Azospirillum and Herbaspirillum bacterial strains. Besides, strains 245 and ZA25 show better performance in promoting plant growth of rice.