This study evaluated ethanol production and cell viability in Saccharomyces cerevisiae cultures under different concentrations of dipotassium phosphate (K₂HPO₄). Batch fermentations were carried out in shake flasks using an orbital thermostatic incubator at 30 °C, with an initial pH of 5.80. The K₂HPO₄ concentration in the culture medium was adjusted to 1.50, 2.70, and 3.20 g L⁻¹. Cultures supplemented with 3.20 g L⁻¹ K₂HPO₄ achieved the highest biomass concentration (12.10 ± 0.30 g L⁻¹). Moreover, ethanol production reached 16% (v/v) under this condition, whereas only 9% (v/v) was obtained at 1.50 g L⁻¹. Regarding volumetric ethanol productivity, a 1.6-fold increase was estimated when the K₂HPO₄ concentration was increased from 1.50 to 3.20 g L⁻¹. Additionally, under the 3.20 g L⁻¹ condition, cell viability remained above 90%, reaching a maximum of 97%, even when ethanol concentration in the broth reached 16% (v/v). In contrast, cell viability decreased by 10% and 7% at 1.50 and 2.70 g L⁻¹, respectively, when ethanol concentrations exceeded 7% (v/v). Overall, the results demonstrated that kinetic parameters such as cell viability, volumetric productivity, and ethanol concentration were positively affected by increasing K₂HPO₄ concentration, supporting its use as a nutritional strategy in the culture medium to enhance ethanol biosynthesis. These findings are particularly relevant as they highlight the potential of K₂HPO₄ as a strategic and economical nutrient to optimize ethanolic fermentations on an industrial scale, contributing to the design of bioprocesses with improvements in metabolic efficiency and prolonged productive capacity throughout the fermentation cycles.
Pesticide spray drift is an off-target pathway in extensive cropping systems that can lead to the exposure of non-target organisms and nearby human populations. This study compared drift-related risk indices for pesticides commonly used in Uruguay using two indicator-based methodologies: POCER (terrestrial organisms and human health) and HAIR (aquatic organisms). Risk indices were calculated using locally derived drift deposition percentages measured at 5, 15, 30, 50, 75, and 100 m downwind under a conservative operational scenario (boom height 120 cm; mean wind speed 20 km h⁻¹) over residue-covered soil. Risk patterns varied according to active ingredient, droplet size, and distance. For bees, chlorpyrifos exceeded the risk threshold (RI ≥ 1) at all distances, while lambda-cyhalothrin exceeded this threshold with fine and medium droplets but not with very coarse droplets. Earthworm risk indices remained below the threshold (RI < 1) at 5 m for all active ingredients. For aquatic organisms, pyraclostrobin and several insecticides exceeded RI ≥ 1 at 15 m, and the use of coarser droplets reduced but did not always eliminate risk. For human health, most substances showed RI < 1 for bystanders and children, whereas paraquat required larger buffer distances under fine and medium droplets. Overall, the results support the use of scenario-based risk indices as comparative tools and suggest that fixed buffer distances may be insufficient for some active ingredients. Product-specific buffer zones and complementary drift mitigation practices should be considered.
The study identified the plant-parasitic nematodes associated with kenaf in selected locations in southwest Nigeria. A survey was conducted in kenaf fields in Ile-Ife and Ikenne, Ibadan and Ilora in September, 2022. The soil sampling procedure involved the collection of samples from 30 distinct locations proximate to the plant roots. Plant-parasitic nematodes (PPNs) were extracted, identified and counted. The frequency of occurrence (FO) and population densities (PD) of the extracted nematodes were calculated. Four genera of PPNs were associated with kenaf in all study locations. These were Meloidogyne, Pratylenchus, Helicotylenchus, and Tylenchus. In Ile-Ife, Meloidogyne had the highest population density per 200 ml soil (72.7%), followed by Helicotylenchus (21.4%), while the lowest density was recorded for Tylenchus (2.0%). In Ikenne, the highest density was recorded for Meloidogyne (47.3%), followed by Pratylenchus (27.9%), and Helicotylenchus (24.4%). The lowest nematode density was recorded for Tylenchus (0.5%). In Ilora, the highest density was recorded for Meloidogyne (66.9%), followed by Helicotylenchus (23.9%), while the lowest density was recorded for Tylenchus (1.4%). The survey in Ibadan showed that nematode with the highest density was Meloidogyne (61.1%), followed by Helicotylenchus (28.0%), while the least density was recorded for Tylenchus (1.3%). This study concluded that four genera of PPN were associated with kenaf in Ikenne, Ile-Ife, Ilora and Ibadan. These were Meloidogyne, Helicotylenchus, Pratylenchus and Tylenchus. The most abundant was Meloidogyne. Therefore, in the management of PPN genera that may impact kenaf production in southwest Nigeria in kenaf, more emphasis should be placed on root-knot nematodes.
The crisis in the Uruguayan dairy industry raises alerts about the intensification processes and the expulsion of family dairy producers who supply industrial plants. In the period 2010-2020, a reduction of almost 800 milk producers was seen in the country. In this context, research was carried out from the qualitative paradigm that sought, from the case of the members of the Agremiación de Tamberos de Canelones (association of dairy farmers of Canelones), to understand the processes of disaffiliation of dairy farmers to the dairy industry between 2005 and 2020. A four-stage methodological strategy was proposed, which triangulated different techniques (interviews, observation, document review) to collect the perspective of disaffiliated dairy family producers. The obtained results allowed for the characterization of milk production at the national level and in the department of Canelones, as well as the identification of different trajectories of disaffiliation of union members in the study period. Various aspects of the intensification process and the increase in the complexity of management driven by the chain arose among the main factors of disaffiliation, which stress the land-family-production relationships, impacting the possibilities of permanence and reproduction in the sector for family producers.
Handroanthus chrysanthus and Swietenia macrophylla are ecologically and economically significant tree species whose populations have declined due to high demand for their timber, adversely affecting their natural regeneration. This study aimed to evaluate the ecophysiological response to increased photosynthetic photon flux density (PPFD) in H. chrysanthus and S. macrophylla seedlings under Amazonian conditions. Assimilation measurements (A) were performed using a portable iFL-LCpro-SD system. The evaluation of A in response to increased PPFD ranged from 25 to 1800 μmol m⁻²s⁻¹. Water use efficiency (WUE) was calculated as the ratio between A and the transpiration rate (E). S. macrophylla exhibited a significantly higher maximum photosynthetic assimilation rate (Amax, 9.4 ± 0.52 µmol CO₂ m⁻² s⁻¹) compared to H. chrysanthus (6.18 ± 0.17 µmol CO₂ m⁻² s⁻¹, p < 0.05), indicating greater carbon fixation efficiency. S. macrophylla showed a maximum WUE (WUEmax) of 13.17 ± 0.24 µmol mmol⁻¹ at 600 μmol m⁻² s⁻¹ PPFD, while H. chrysanthus reached its WUEmax (6.16 ± 0.23 µmol mmol⁻¹) at 750 μmol m⁻² s⁻¹ PPFD. These results suggest that S. macrophylla exhibits higher WUE under high irradiance conditions, potentially due to more efficient stomatal regulation and an optimized balance between carbon fixation and water loss via transpiration.
