The jambu (Acmella oleracea) production can be influenced by the growing season and light available for metabolic processes. This study aimed to assess the agronomic and physiological performance of two jambu varieties, under different shading levels, during the winter and summer of the Brazilian Amazon. Two random block experiments were conducted, in a 2 x 4 factorial scheme, consisting of two jambu varieties (yellow and purple flower) and four shading levels (0, 30, 50 and 70 %), with four replications. Physiological, growth and yield traits were assessed. There was no significant interaction between treatments and growing seasons (Amazon winter and summer) for growth or yield traits, nor between treatments for the physiological characteristics. The cultivation without shading screen can increase the shoot dry weight of both varieties; the yellow flower variety exhibited early-onset flowering regardless of the shading screen used; the “Amazon summer” growing season increased the jambu yield by 33 %, while the 70 % shading reduced the net photosynthetic rate, consequently not favoring the vegetative development of the jambu plants. As such, it is recommended that the yellow and purple flower jambu varieties be grown without shading screen in the Amazon summer.

Water-use efficiency (WUE) plays a crucial role in sustainable crop production, particularly in water-limited environments where maximizing natural resource use is essential. This study evaluated the physiological and agronomic performance of two Piper nigrum cultivars, Clonada and Uthirankotta, grown under different soil water potential conditions. The trial was conducted in a 1930 m² field using a randomized block design and drip irrigation system, calibrated to 3.55 L h⁻¹ with a uniformity of 97%. Soil water availability was managed based on daily tensiometer readings at 20 and 30 cm depths, triggering irrigation at defined tensions (10–55 kPa). Clonada exhibited higher net CO₂ assimilation rates (A) and stomatal conductance (g_s), but these responses did not lead to higher yields. In contrast, Uthirankotta consistently maintained superior water-use efficiency and yield across all soil moisture conditions by favoring water conservation and targeted biomass allocation over maximized gas exchange. Both cultivars performed optimally at a soil water potential range of 25–35 kPa, with declines in yield and gas exchange parameters at higher tensions (45–55 kPa). Under such conditions, Uthirankotta was 51.3% more water-use efficient and 40.8% more productive than Clonada. Based on this, a Principal Component Analysis (PCA) further demonstrated distinct physiological profiles, underscoring trade-offs between yield and water-use strategies. These results highlight the significance of cultivar selection for optimizing WUE and provide valuable insights into irrigation management and breeding programs aimed at boosting black pepper performance under water-limited conditions.

Considering the lack of technical information on the water depth and nitrogen fertilization via fertigation in bell pepper cultivation, this work aimed to provide management data for its production in the northern region of Brazil. The experiment was carried out in a greenhouse at FEIGA / UFRA, with a 1.0 x 0.50 m spacing, in a randomized block design, with a 5 x 4 factorial scheme, with three replications. The treatments consisted of five water tensions in the soil (15, 25, 35, 45 and 65 kPa) and four nitrogen doses (0, 135, 265 and 395 kg.ha-1). There was no interaction between the factors of water tension in the soil and nitrogen doses for any of the variables analyzed. Height of plants, fresh shoot mass and dry shoot mass showed significant differences only for nitrogen doses. Predawn potential, showed significant difference for soil water tensions and nitrogen doses. Ahead of the conditions under which this work was carried out and the results obtained for the variables analyzed for the bell pepper cultivation in a protected environment, we found that the soil water tension of 15 kPa and the nitrogen dose of 265 kg.ha-1 were ideal for the crop.

Water-use efficiency (WUE) is a crucial parameter for sustainable crop production, particularly in water-limited environments where optimizing resource utilization is essential for maintaining productivity and resilience. This study investigates the physiological and agronomic responses of two black pepper (Piper nigrum) cultivars, Clonada and Uthirankotta, under varying soil water potentials and along the time. Results indicate that WUE varies significantly between cultivars due to distinct physiological strategies. Clonada exhibited higher photosynthetic rates, stomatal conductance, and gas exchange efficiency, leading to greater yield performance under moderate stress conditions. Conversely, Uthirankotta demonstrated consistently higher WUE across all water conditions, prioritizing water conservation and biomass accumulation over gas exchange efficiency. Both cultivars displayed peak performance at 25–35 kPa soil water potential, with yield and physiological efficiency declining at higher tensions. Principal Component Analysis (PCA) confirmed distinct physiological profiles, reinforcing the trade-offs between productivity and water-use strategies. These findings highlight the importance of cultivar selection for optimizing WUE in black pepper cultivation and provide insights for improving irrigation management and breeding programs.