Minerals in plant food: effect of agricultural practices and role in human health. A review

An understanding of agroecosystems is key to determining effective farming systems. Here we report results from a 21-year study of agronomic and ecological performance of biodynamic, bioorganic, and conventional farming systems in Central Europe. We found crop yields to be 20% lower in the organic systems, although input of fertilizer and energy was reduced by 34 to 53% and pesticide input by 97%. Enhanced soil fertility and higher biodiversity found in organic plots may render these systems less dependent on external inputs.

This paper provides a personal perspective of the role of abnormal renal-pressure natriuresis in the pathogenesis of hypertension. Direct support for a major role of renal-pressure natriuresis in long-term control of arterial pressure and sodium balance comes from studies demonstrating that (1) pressure natriuresis is impaired in all forms of chronic hypertension and (2) prevention of pressure natriuresis from operating, by servo-control of renal perfusion pressure, also prevents the maintenance of sodium balance hypertension. Although the precise mechanisms of impaired pressure natriuresis in essential hypertension have remained elusive, recent evidence suggests that obesity and overweight may play a major role. Obesity increases renal sodium reabsorption and impairs pressure natriuresis by activation of the renin-angiotensin and sympathetic nervous systems and by altered intrarenal physical forces. Chronic obesity also causes marked structural changes in the kidneys that eventually lead to a loss of nephron function, further increases in arterial pressure, and severe renal injury in some cases. Although there are many unanswered questions about the mechanisms of obesity hypertension and renal disease, this is one of the most promising areas for future research, especially in view of the growing, worldwide "epidemic" of obesity.

It has been proposed that salicylic acid (SA) acts as an endogenous signal molecule responsible for inducing abiotic stress tolerance in plants. The effect of varying salicylic acid (SA) supply (0, 0.1, 0.5 and 1.0mM) on growth, mineral uptake, membrane permeability, lipid peroxidation, H(2)O(2) concentration, UV-absorbing substances, chlorophyll and carotenoid concentrations of NaCl (40 mM) stressed maize (Zea mays L.) was investigated. Exogenously applied SA increased plant growth significantly both in saline and non-saline conditions. As a consequence of salinity stress, lipid peroxidation, measured in terms of malondialdehyde (MDA) content and membrane permeability was decreased by SA. UV-absorbing substances (UVAS) and H(2)O(2) concentration were increased by increasing levels of SA. SA also strongly inhibited Na(+) and Cl(-) accumulation, but stimulated N, Mg, Fe, Mn and Cu concentrations of salt stressed maize plants. These results suggest that SA could be used as a potential growth regulator to improve plant salinity stress resistance.