The plant water status is crucial for growth and production, but the current climate change scenario makes it challenging to match the water plant demand. Blueberries are an economically important crop and play an acknowledged role in human health due to their antioxidant compounds. This research aimed to determine whether the exogenous application of methyl jasmonate (MeJA) improves the antioxidant defense mechanisms for protecting the photosynthetic performance in the blueberry plant cultivar ‘Brigitta’ under the stress condition of a water deficit (WD). A greenhouse experiment was carried out under a 16-h light period, at 20 °C, and 60–80% relative humidity for two weeks before the application of MeJA to the blueberry plants (Vaccinium corymbosum, cultivar ‘Brigitta’). The following treatments were maintained for 7-days: (i) 80% field capacity (NoWD), (ii) 80% field capacity plus MeJA application (NoWD + MeJA), (iii) 20% field capacity (WD), and (iv) 20% field capacity plus MeJA application (WD + MeJA). The MeJA was sprayed as an aqueous solution of 10 µM MeJA over the plant’s foliar system. At the end of the assay, the blueberry leaves were analyzed for their relative water content, specific leaf area, lipid peroxidation, total antioxidant activity, total phenols, total anthocyanins, anthocyanidin compounds, and photosynthetic performance. The ‘Brigitta’ cultivar showed a significant decrease in the oxidative stress at leaf levels, with an increase in antioxidant activity, phenolic compounds, total anthocyanins, delphinidin, petunidin, antheraxanthin, zeaxanthin, and an improvement in photosynthetic performance parameters. The ‘Brigitta’ blueberry cultivar was shown to be susceptible to WD, which mainly decreased photosynthesis. However, the application of MeJA to the leaves induced metabolic changes through an increase of the antioxidant strategy within the plant to counteract the negative effects of WD and protect the photosynthetic apparatus, which allowed the ‘Brigitta’ cultivar to withstand the period of a WD.

Soil enzymes can be sensitive indicators of C changes in forest soils produced by global warming. This study assessed the response to temperature of soil enzymes in forest soils from the fragile cold ecosystems of Western Patagonia (Chile), to be used as indicators of the biological C emissions from the soil under climate change for this Region. Soil from two sites of Nothofagus forest were sampled (0-5 cm), and soil C mineralization (21 days of soil incubation) and the enzyme activities of N-acetyl-β-glucosaminidase (NGA, linked to C and N cycles), β-glucosidase (BG, linked to C cycle), and endo-1,4-β-glucanase (CMCase, linked to C cycle) were measured at 5°C and 20^oC. Additionally, sensitivity of enzyme activities was measured at 0, 5, 10 and 20^oC during experimental protocol incubation procedure, and energy activation (Ea) and Q₁₀ parameters were calculated. At both sites, the NGA activity mirrored the microbial activity, when temperature rose from 5 ºC to 20 °C. The NGA showed Ea higher than BG, indicating that the release of N-acetyl-glucosamine was more sensitive to temperature than the release of glucose, related to BG. The results suggest the applicability of NGA as potential indicator to assess effects of global warming in forest soils from Patagonia.