RESUMO
Boron (B) is toxic to most plant species when accumulated in high concentrations. Differences in a plant's ability to adapt to high concentrations of B may depend on the origin of the germplasm. Chilean and domestic (U.S.) germplasm, corn (Zea mays L.), carrots (Daucus carotas), tomato (Lycopersicum esculentum L.), and alfalfa (Medicago sativa L.) were evaluated for germination, emergence of cotyledonary leaves, and tissue B accumulation under high-B conditions in both an environmental growth chamber and a greenhouse. Increasing B levels (20-40 mg B liter-1) inhibited the percentage germination for both the Chilean and domestic germplasm. Chilean germplasm exhibited generally a greater percentage of healthy cotyledonary leaves at the 20 mg B liter-1 treatment than the domestic germplasm. Comparing B concentrations between both germplasm grown and irrigated with B-enriched water (10-20 mg B liter-1) under greenhouse conditions, leaves from domestic germplasm contained more B. Moreover, B troxicity symptoms were more severe for the tested plant species from the domestic germplasm. Apparent B tolerance by germplasm of different origin should be further tested under field conditions.
Assuntos
Boro/farmacocinética , Boro/toxicidade , Fenômenos Fisiológicos Vegetais/efeitos dos fármacos , Plantas/metabolismo , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Poluentes Químicos da Água/farmacocinética , Poluentes Químicos da Água/toxicidade , Chile , Cotilédone/efeitos dos fármacos , Cotilédone/crescimento & desenvolvimento , Cotilédone/metabolismo , Germinação/efeitos dos fármacos , Desenvolvimento Vegetal , Sementes/metabolismo , Estados UnidosRESUMO
The paper presents a multidimensional psychological model of determinants of health behavior, tested empirically in three countries to ascertain its validity. The model postulates that given that ethnic, socioeconomic, and biological statuses (exogenous variables) are homogeneous, a health risk-taking behavior in a population is a function of direct, additive, and interaction effects of five categories of independent variables both internal to the persons and external in the action environment. Although the model is tested on contraceptive behavior, it is argued that the determinants and basic processes of this risk-taking behavior are similar to those involved in other health risk behaviors and that the five basic factors identified affect nutritional behaviors as well. The paper presents several broad implications on the model for nutrition education and research; but holds that specific implications could be best derived by the specialists in nutrition field.
PIP: This paper presents a multidimensional psychosocial model of determinants of health behavior, tested empirically in 3 countries to ascertain its validity. The model postulates that given that ethnic, socioeconomic, and biological statuses (exogenous variables) are homogeneous, a health risktaking behavior in a population is a function of direct, additive and interaction effects of 5 categories of independent variables both internal to the persons and external in the action environment. Although the model is tested on contraceptive behavior, it is argued that the determinants and basic processes of this risktaking behavior are similar to those involved in other health risk behaviors and that the 5 basic factors identified affect nutritional behaviors as well. The paper presents several broad implications of the model for nutrition education and research but holds that specific implications could be best derived by specialists in the field of nutrition.