RESUMO

Kinematic indicators, including certain strain fringes, represent an important group of structures related to the progressive deformation in rocks. The evolution of these fibrous textures can be explained by the combination of multiple mechanisms of deformation and fluid flow, mainly controlled by the orientation of the strain field and the morphology of the grains. In general, the observations are done with an optical microscope and compared with computational models of growth. This work proposes a combination of crystallographic and cathodoluminescence data obtained in rocks from banded iron formations of the Iron Quadrangle in Brazil to represent an example of how complementary analytical techniques can be useful to understand geological problems. The chosen sample exhibits a strain fringe structure of quartz around a clast of magnetite partially transformed into goethite and hematite. Through the crystallographic data it was possible to identify the grain boundary morphology and domains of low deformation areas. On the other hand, the cathodoluminescence signal evidenced the occurrence of grains with a higher concentration of crystalline defects.

RESUMO

In previous multicentre studies, the influence of a homeopathic ultra-high dilution of gibberellic acid on wheat growth was scrutinized. Data showed that this test dilution slowed down stalk growth when experiments were performed in the autumn season. The aim of this work was to test the hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth-inhibiting effect of the ultra-high dilution of the plant hormone. Grains of winter wheat (Triticum aestivum, 500 or 1000 per group) were pretreated with (non-agitated) gibberellic acid 10-5, 10-4 and 10-3 parts by weight (Ge-5, Ge-4, Ge-3) or with water (?W0?) for control prior to further treatment. Grains were then observed under the influence of extremely diluted gibberellic acid (10-30 parts by weigth) prepared by stepwise dilution and agitation according to a protocol derived from homeopathy (?G30x?). Analogously prepared water was used for control (?W30x?). Seedlings were allowed to develop under standardized conditions for 7 days; plants were harvested and stalk lengths were measured. Of the four pretreatment variants under study, Ge-3 yielded most growth, followed by Ge-4 , Ge-5 and finally W. This outcome was modulated by the application of G30x in that the inhibition obtained with G30x as compared to W30x was the greater the lower the pretreatment concentration of G had been. The hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth inhibiting effect of G30x had to be rejected. Rather, G30x slowed down stalk growth most in the W0 group with p < 0.001, only moderately in the Ge-5 and Ge-4 group and not at all in the Ge-3 group.

Assuntos

RESUMO

In previous multicentre studies, the influence of a homeopathic ultra-high dilution of gibberellic acid on wheat growth was scrutinized. Data showed that this test dilution slowed down stalk growth when experiments were performed in the autumn season. The aim of this work was to test the hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth-inhibiting effect of the ultra-high dilution of the plant hormone. Grains of winter wheat (Triticum aestivum, 500 or 1000 per group) were pretreated with (non-agitated) gibberellic acid 10-5, 10-4 and 10-3 parts by weight (Ge-5, Ge-4, Ge-3) or with water (?W0?) for control prior to further treatment. Grains were then observed under the influence of extremely diluted gibberellic acid (10-30 parts by weigth) prepared by stepwise dilution and agitation according to a protocol derived from homeopathy (?G30x?). Analogously prepared water was used for control (?W30x?). Seedlings were allowed to develop under standardized conditions for 7 days; plants were harvested and stalk lengths were measured. Of the four pretreatment variants under study, Ge-3 yielded most growth, followed by Ge-4 , Ge-5 and finally W. This outcome was modulated by the application of G30x in that the inhibition obtained with G30x as compared to W30x was the greater the lower the pretreatment concentration of G had been. The hypothesis that pretreatment of grains with high concentrations of gibberellic acid would enhance the growth inhibiting effect of G30x had to be rejected. Rather, G30x slowed down stalk growth most in the W0 group with p < 0.001, only moderately in the Ge-5 and Ge-4 group and not at all in the Ge-3 group.(AU)

Assuntos