The aim of this study was to assess the effect of different irrigation strategies in virgin olive oil (VOO) composition and quality of cv. Cobrançosa, integrated in a protected denomination of origin of “Azeite de Trás-os-Montes” in the Northeast of Portugal. Three irrigation treatments were applied: T2-full irrigation that received a seasonal water equivalent to 100% of estimated crop evapotranspiration (ETc), T1-continuous deficit irrigation (30% ETc) and T0- rainfed treatment. Data were collected from two consecutive crop years (2005-2006). Irrigation regimes had a minor effect on standard quality indices (free fatty acids, peroxide value, K232 and K270) of VOO and in fatty acid composition. Total polyphenols decreased up to treatment T2, and were strongly related to the water stress integral, suggesting that the effect of irrigation on this variable occurs along the crop season and not just during the oil accumulation phase. A strategy of continuous deficit irrigation with only 30% of maximum ETc may have an advantageous effect, as it increased oil yield to more than double that of rainfed conditions while VOO quality was similar.

Soil contamination by trace elements is a worldwide concern that can result from several sources, such as mining, smelting, car traffic exhaust, agriculture plant protection products such as fungicides, and fertilizers. Among the metals involved, copper can cause alterations in the photosynthetic, respiratory, and enzymatic processes of plants, leading to reduced growth of roots and shoots. An alternative to dealing with metals present in the soil is phytoremediation, which consists of using plants to extract or stabilize these elements. The leguminous Crotalaria juncea is widely used as a green manure and may be advantageous due to its capacity for biological nitrogen fixation and biomass accumulation. This research aimed to evaluate the growth and physiological behaviour of C. juncea in copper-contaminated soil and its potential use as a phytoremediation plant. For the fresh and dry mass of shoots and roots, compared with 30 mg.dm⁻³ of Cu, there was a decrease in values with the increase in concentrations up to a dose of 480 mg.dm⁻³. The roots were less sensitive to increased Cu concentrations than the shoots. The tolerance index decreased as copper concentrations in the soil increased. From 60 mg.dm⁻³, its vegetative growth decreased, but C. Juncea was able to tolerate and accumulate copper in the root system, presenting high potential as a phytostabilizing species.

Manganese (Mn) is crucial as a trace element for plant metabolism, but high concentrations in soil can induce symptoms of toxicity. This study aimed to evaluate the metabolism of nitrogen compounds and biomass production in Canavalia ensiformis and Cajanus cajan, clarifying the effects of this metal on nitrogen metabolism. The soil was treated with Mn concentrations of 80, 100, 120, 140, and 160 mg kg⁻¹. Differential responses were observed in the metabolism of nitrogenous compounds between species. C. cajan affected nitrogen metabolism in shoots, roots, and nodules, with significant variations in amino acids, total soluble proteins, ureides, and root biomass concentration. In contrast, C. ensiformis showed stability in the concentrations of compounds, mainly ureides, and proteins, even with increasing doses of Mn in the soil. These findings highlight the importance of nitrogen metabolism in legumes studied as a key aspect for understanding their Mn tolerance mechanisms in soil.