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Family farms are one of America’s cultural icons and an important element of American farming tradition. However, their definition is neither clear-cut nor unambiguous; as indicated by the authors of this article, the role and significance of family farms are different for all currently used definitions. Comparing and contemplating the definitions specified by the USDA and UN-FAO, as well as the concepts put forth by American organizations, e. g. the National Family Farm Coalition or Family Farm Defenders, the authors point out sizable differences in numbers and basic characteristics of family farms. These differences result from factors related to scale of production, extent of land ownership and tenancy, as well as various social and regional influences. The two latter categories encompass issues affecting mid-sized farms (agriculture of the middle), the significance of income from extra-agricultural labor for the family farm budget, the role and importance of hired labor, and the characteristics and extent of land tenancy. The authors stress the importance of family farming in maintaining the vitality of local communities and food security in the US along with its role in protecting biodiversity and the environment. The closing part of the article focuses on addressing US rural policy, which should count protecting family farms among its key goals.
Silicon has been widely reported to have a beneficial effect on improving plant tolerance to biotic and abiotic stresses. However, the mechanisms of silicon in mediating stress responses are still poorly understood. Sorghum is classified as a silicon accumulator and is relatively sensitive to salt stress. In this study, we investigated the short-term application of silicon on growth, osmotic adjustment and ion accumulation in sorghum (Sorghum bicolor L. Moench) under salt stress. The application of silicon alone had no effects upon sorghum growth, while it partly reversed the salt-induced reduction in plant growth and photosynthesis. Meanwhile, the osmotic potential was lower and the turgor pressure was higher than that without silicon application under salt stress. The osmolytes, the sucrose and fructose levels, but not the proline, were significantly increased, as well as Na+ concentration was decreased in silicon-treated plants under salt stress. These results suggest that the beneficial effects of silicon on improving salt tolerance under short-term treatment are attributed to the alleviating of salt-induced osmotic stress and as well as ionic stress simultaneously.
To acquire basic information about species’ salt tolerance prior to applying Elaeagnus oxycarpa to phytoremediate degraded saline areas, salt-induced changes in growth, photosynthesis, and osmolyte accumulation in E. oxycarpa seedlings were investigated. The responses of 120-day-old seedlings to NaCl application (0, 50, 100, 200, or 300 mM) were assessed for 30 days. Plant growth and biomass were not affected at low salinity (50 mM NaCl) and decreased linearly with an increase in salinity. However, seedlings tolerated up to 300 mM NaCl without any effect on survival and grew normally without toxic symptoms (such as yellow leaves at the base of the seedlings and new leaves burn) at 200 mM NaCl. Gas exchange was unaffected at 50 mM NaCl but was reduced at ≥100 mM NaCl. Maintenance of photosystem II (PSII) function (Fv/ Fm) at high salinity (200 mM) could support E. oxycarpa growth. Leaf and root Na⁺ concentrations increased with increasing salinity, although most Na⁺ was retained in the root system at low and moderate salinity (50 and 100 mM NaCl), whereas high concentrations of nutrients (e.g., K⁺ and Ca²⁺) were maintained in the leaves. The seedlings accumulated a set of important osmolytes in leaves under salt stress, showing a marked increase in sucrose, β-alanine betaine, proline, and glycine at 200 and 300 mM NaCl. These compounds indirectly may contribute to osmotic adjustment by maintaining high cation concentrations and osmoprotective functions when stress becomes severe. We conclude that salt tolerance in E. oxycarpa is based on maintenance of PSII function, ionic homeostasis, and accumulation of osmolytes.
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