Elemental composition of strawberry plants inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3 assessed by scanning electron microscopy and energy dispersive X-ray analysis

GUERRERO MOLINA, MA. FERNANDA; LOVAISA, NADIA; SALAZAR, SERGIO M; DÍAZ RICCI, JUAN C.; PEDRAZA, RAÚL O.

PLANT BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 16 p. 726 - 731

1435-8603

The elemental composition of strawberry plants (Fragaria ananassa cv. Macarena)inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3,and non-inoculated controls, was studied using scanning electron microscopy (SEM)and energy dispersive X-ray (EDS) analysis. This allowed simultaneous semi-quantificationof different elements in a small, solid sample. Plants were inoculated andgrown hydroponically in 50% or 100% Hoagland solution, corresponding to limitedor optimum nutrient medium, respectively. Bacteria-inoculated plants increased thegrowth index 45% and 80% compared to controls when grown in 100% and 50% Hoaglandsolution, respectively. Thus, inoculation with A. brasilense REC3 in a nutrientlimitedmedium had the strongest effect in terms of increasing both shoot and rootbiomass and growth index, as already described for Azospirillum inoculated intonutrient-poor soils. SEM-EDS spectra and maps showed the elemental compositionand relative distribution of nutrients in strawberry tissues. Leaves contained C, O, N,Na, P, K, Ca and Cu, while roots also had Si and Cl. The organic fraction (C, O and N)accounted for over 96.3% of the total chemical composition; of the mineral fraction,Na had higher accumulation in both leaves and roots. Azospirillum-inoculated andcontrol plants had similar elemental quantities; however, in bacteria-inoculated roots,P was significantly increased (34.33%), which constitutes a major benefit for plantnutrition, while Cu content decreased (35.16%).