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Mineral fertilizers are widely used in conventional agriculture to boost crop yield. However, their overuse can lead to inefficient nutrient use by plants, causing environmental issues like nutrient losses and water pollution. Recently, there has been a growing interest in using chars, such as biochar or hydrochar (HC), as sustainable alternatives to traditional fertilizers for enhancing plant growth. Yet, exploring the potential toxic impact of these materials on soil and plants is an area that requires further investigation. Similarly, assessing their fertilizing capacity requires studies beyond plant biomass analysis. For this reason, the present study focuses on evaluating the impact of applying HC derived from chicken manure on the use efficiency of some of the most important macronutrients for sunflower plants (Helianthus annuus L.). Additionally, it was studied under both well-irrigated and drought conditions to understand the performance of the plants under two different irrigation scenarios. For this purpose, a greenhouse soil pot experiment lasting for 77 days was conducted. HC was administered to a soil at application rates of 3.25 and 6.5 t ha-1 (HC-3.23 and HC-6.5). Comparative mineral fertilizer treatments (NPK) with equivalent total nitrogen contributions as the amendment were incorporated for evaluation. Under both irrigation conditions, soils treated with HC-6.5 demonstrated significantly increased total plant and seed biomass yields in comparison to untreated soils, but no significant differences were observed compared to the mineral fertilizer counterpart. When parameters related to nutrient use efficiency were analyzed, HC-6.5 treatment under both irrigation conditions exhibited the highest values in S uptake efficiency. Interestingly, regarding K, plants treated with HC-6.5 showed two strategies of use efficiency depending on the irrigation condition. While under well-irrigated conditions, these plants demonstrated a higher K uptake efficiency

In recent decades, the potential use of chars, such as biochar or hydrochar, as soil amendments to enhance plant growth, has garnered significant interest. However, understanding potential toxic impact of these materials on soil and plants remains an area requiring further exploration. In this study, the effect of applying hydrochar (HC) derived from chicken manure on the yield and nutritional quality of sunflower (Helianthus annuus L.) seeds was assessed under both wellirrigated and water deficit (WD) conditions. To address it, the HC was applied to a Cambisol at rates of 3.25 and 6.5 t ha-1. Mineral fertilizer treatments with equivalent total nitrogen contributions as the amendment were included for comparison. Sunflower plants were cultivated in pots under two irrigations conditions (60 and 30% of the soil water holding capacity). After 77 days of cultivation, the plants were harvested, and the content of macro- and micronutrients, heavy metals in both seeds and leaves, as well as the seed fatty acid composition, were analyzed. Additionally, soil nutrient contents were assessed post-experiment. Initially, HC application did not cause a noticeable change in soil nutrient composition. However, both HC applications demonstrated high productivity under well-irrigated conditions. Likewise, under WD conditions, the best yields were achieved with a HC dose of 6.5 t ha-1. Conversely, the composition of the different fatty acids in the seed oil remained unaffected by the treatments and irrigation conditions. Nonetheless, seed nutrient content was notably affected, particularly in plants treated with 6.5 t ha-1. Under well-irrigated conditions, the seeds of these plants exhibited decreased K and P levels, along with higher levels of toxic elements and heavy metals such as Al, Ba, Cd, Pb, and Sr. Under WD conditions, the impact of the treatment on heavy metals contents was less pronounced, but there was a marked reduction of seed macronutrient content (Ca, K, Mg, P and S).

Hydrothermal technologies are considered promising for producing valuable products like hydrochar from renewable biomass waste. Hydrochar (HC), acting as a hopeful substitute for current commercial fertilizers, has the potential to serve as a soil amendment, improving soil quality, microbial activity, and crop production. However, our understanding of the underlying mechanisms of hydrochar biogeochemical processes and their effects on planted soils is still challenging. Additionally, there is limited knowledge about the effects under deficit irrigation conditions. The aim of this study was to assess the impact of the interaction between treated soil, plants, and microorganisms on soil organic matter (SOM), soil nutrients, microbial activity, plant growth, and irrigation management in soils.

Climate change, with its increasing temperaturas and prolonged drought events, poses pressing challenges for agricultura, food security and the environment. To address these concerns, alternative agricultural practices are needed, including sustainable fertilization methods and improved water use efficiency. Promoting the circular economy and environmental sustainability, hydrothermal carbonization offers a promising solution by converting biomass waste into hidrochar (HC), a carbon-rich soil amendment with the potential to serve as a substitute form traditional fertilizers and enhance water management in agriculture. The aim of this study was to evaluate the use of HC as an alternative fertilizer and investigate its impact on plant productivity and water status under two different irrigation conditions.

Invitación por parte del Dr. Jorge Medina Otárola para impartir una presentación oral en españól, en la jornada de seminario con título "Valorización de residuos agropecuarios y sus potenciales usos agroambientales en contexto de cambio climático" del Campus Colchagua de la Universidad de O'Higgins (San Fernando, Chile). Pueden ver en video a través de @YouTube, la presentación a partir del minuto 49:30 el doctorando Francisco J. Moreno-Racero del IRNAS CSIC hizo la presentación oral: Multidisciplinary approach on the impact of hydrochar on the soil-plant-microorganisms systems.en la jornada de seminarios con título "Valorización de residuos agropecuarios y sus potenciales usos agroambientales en contexto de cambio climático" del Campus Colchagua de la Universidad de O'Higgins (San Fernando, Chile).https://www.youtube.com/live/M7B06bfpW0Q?feature=shared

Climate change, with its increasing temperaturas and prolonged drought events, poses pressing challenges for agricultura, food security and the environment. To address these concerns, alternative agricultural practices are needed, including sustainable fertilization methods and improved water use efficiency. Promoting the circular economy and environmental sustainability, hydrothermal carbonization offers a promising solution by converting biomass waste into hidrochar (HC), a carbon-rich soil amendment with the potential to serve as a substitute form traditional fertilizers and enhance water management in agriculture. The aim of this study was to evaluate the use of HC as an alternative fertilizer and investigate its impact on plant productivity and water status under two different irrigation conditions.

Hydrothermal technologies are considered promising for producing valuable products like hydrochar from renewable biomass waste. Hydrochar (HC), acting as a hopeful substitute for current commercial fertilizers, has the potential to serve as a soil amendment, improving soil quality, microbial activity, and crop production. However, our understanding of the underlying mechanisms of hydrochar biogeochemical processes and their effects on planted soils is still challenging. Additionally, there is limited knowledge about the effects under deficit irrigation conditions. The aim of this study was to assess the impact of the interaction between treated soil, plants, and microorganisms on soil organic matter (SOM), soil nutrients, microbial activity, plant growth, and irrigation management in soils.

Chloride (Cl-) has been traditionally considered a harmful ion for plants because of its high accumulation in organs and its antagonism with nitrate (NO3-) under salinity conditions.1,2 However, we recently demonstrated the opposite when it gradually accumulated in leaves, defining Cl- as a beneficial macronutrient for plants that improves growth and the efficiency in the use of water, carbon and nitrogen (N).3,4 A major problem for crops is the inefficient application of N fertilizers, causing N deficiency stress in plants and environmental and human health issues5. Therefore, in this work we analysed physiological traits in tomato plants grown under different Cl- and NO3- treatments. . Our results showed that the application of 5 mM Cl- allowed to reduce NO3- supply, maintaining similar plant growth. Overall, Cl- remains as a potential strategy to reduced N deficiency stress symptoms improving growth, turgor maintenance, photosynthesis and antioxidant response in tomato plants.

The use of peat in traditional agricultural systems and nursery enterprises is an environmental preoccupation. Since the high CO2 and greenhouse gas (GHG) emission due to peat excavation and transport contributes considerably to climate change and global warming it is key to find alternative material which can substitute this limited resource. One of this represents biochar. As a potential highly recalcitrant and aromatic "humic substance" (HS) it was shown to promote sustainable agriculture, contributing to the concept of circular economy, leveraging biomass waste and boosting nutrient recovery and use efficiency. In this work we partially replaced peat with different amounts of biochar obtained from vineyard pruning as plant growing substrates whereas implementing N (Nitrogen) fertirrigation. We studied the effect on the growth, different content of N forms and other nutrient dynamics impact of lettuce plants grown under greenhouse and semi-hydroponics conditions. Substrate mixtures contained 30% of vermiculite and 70% of different biochar:peat treatments as follows: 0:70 (B0), 15:55 (B15), 30:40 (B30), 50:20 (B50), and 70:0 (B70). Higher biochar treatments increased pH and electrical conductivity of the substrate, negatively affecting plant growth and germination. The substitution of 30% peat by biochar (B30) delayed seed germination but improved plant growth and N use efficiency without showing stress symptoms. This is related with a higher nitrate (NO3-) retention capacity in the substrate, leading to higher allocation and flux of N to the plant shoot and a better performance of N metabolic enzymes (NR, GS, GOGAT, GDH). The treatment B30 also increased the water holding capacity of the substrate, which may enhance soil moisture characteristics and pore size distribution, maximizing water availability to plants.

The use of peat in traditional cultivation systems and in commercial nurseries is an environmental problem. In this work, we evaluated the partial replacement of peat with different amounts of biochar sourced from vineyard pruning as plant growing substrates. We studied its effect on the growth of lettuce plants under greenhouse and semi-hydroponic conditions. Substrate mixtures contained 30% (v/v) of vermiculite and 70% (v/v) of different biochar:peat treatments as follows: 0:70 (B0), 15:55 (B15), 30:40 (B30), 50:20 (B50), and 70:0 (B70). Higher biochar treatments increased the pH and electrical conductivity of the substrate, negatively affecting plant growth and germination (especially in B70). The partial substitution of peat by 30% biochar (B30) delayed seed germination but improved plant growth and nitrogen use efficiency (NUE), with shoots containing higher levels of organic nitrogen and nitrate. Moreover, it increased the water holding capacity (WHC) and led to an efficient use of nutrients. Our study demonstrates that biochar can successfully replace and reduce peat and N fertilizer consumption. This has the potential to promote more sustainable farming with positive impacts on both plant growth and the environment.

Chloride (Cl-) has traditionalIy been considered a damaging ion for agriculture because of its toxicity under salinity conditions and antagonism with nitrate (NO3-). However, Cl- nutrition at macronutrient levels (1-5 mM) has been proved as a potential strategy to improve the performance of different crops·. Mild salinity levels (20-40 mM NaCl) has al so been formulated as a promising way to increase phytochemicals withminimalloss of yield, modulating positively quality of vegetables· Among other effects, the beneficial Cl- nutrition reduces between 25-75% the NO3- content in leaves of adul! tobacco plants, potentialIy harmful to human health . The study of a potential fertilization with optimal N03-/CL- ratios is relevant to identify the best performance and nutritional quality ofyoung lettuce plants, for reducing NO3-, accumulation in leaves and nitrogen overfertilization practices, meaning a more sustainable agriculture for environment and human health. Therefore, in this work we aimed to elucidate the effects of el' supplied at both macronutrient and mild el' salinity levels on physiological parameters, el- and N03- content, ascorbic acid, and different antioxidant capacity tests in lettuce baby-leaves.Lettuce seeds were grown in semi-hydroponics under greenhouse conditions, and treated with four NO3- treatments: 5, 9, 12 and 15 mM of a mix of NO3-, salts. In addition, plants from each NO3- treatment were treated with two er treatments: 5 (5CL) and 25 (25CL) mM of a mix of Cl- salts, and a control treatment with a mix of sulphate+phosphate (SP) salts. Plants were harvested at 15 and 30 days after sowing, and tissues were stored for the analysis anions and antioxidants content.lnterestingly, our results revealed that the 25CL treatment caused the strongest increase of biomass and leaf area at 5 and 9 mM of NO3- levels compared to SP treatments, whereas the los s of water and the N03- contenl was significantly reduced in 25CL and 5CL treatments compared to SP trea

Chloride (Cl-) is an anion that participates in key processes for plants, such as photosynthesis and osmotic regulation1. Cl- has recently been defined as a beneficial macronutrient for higher plants, due to the stimulation of plant growth, inducing morphological and cellular changes that include the stimulation of leaf cell size, reducing stomatal conductance and inducing additional osmolarity and turgor in adult tobacco plants. Thus, Cl- generates bigger plants with better water and nitrogen use efficiency and, as a result, a better photosynthetic performance2,3. Roots are in charge of searching for water and nutrients which are essentials for plant development and growth. Nutrients distribute to the rest of plant organs via the vascular system, being regulated by complex hormonal mechanisms4. Although some proteins regulating Cl- homeostasis (e.g. Cation-Chloride Cotransporter) have been reported to be important for root cell elongation5, little is known about the effect of Cl- nutrition on root developmental processes during early vegetative growth. To this aim, in this work tobacco and tomato seeds were sown under greenhouse conditions and seedlings were harvested at different developmental stages, from 8 to 35 days after sowing. A Cl- treatment (5 mM of Cl- salts) was supplemented to the basal nutrient solution, and a treatment with a mix of sulphate+phosphate salts (SP) with the same cationic content was used as a control. Afterwards, biomass and root system architecture (RSA) parameters (primary root length, number and length of lateral roots) were analysed by using `ImageJ¿ and `Optimas¿ software. Results from this work showed that the Cl- treatment generated bigger plants with longer primary roots and shorter lateral roots during the early vegetative development. These effects may be caused by higher cell size or division during the root development, with a possible effect on hormonal regulation. Therefore, these root architecture changes are particularly

Chloride (Cl-) has been revealed as an essential micronutrient and a beneficial macronutrient for adequate plant growth and development, while it can be toxic under salt stress conditions. Active transporters involved in cell Clinflux, along with channels that mediate Clefflux are important points of regulation of plant Clhomeostasis. Presently, there is adequate understanding of plant Cltransport mechanisms at the electrophysiological level. However, the molecular identity of many transporters remains uncharacterized. Rapid-type ALMT anion channels mediate malate, sulphate, Cland nitrate (NO3-) transport in plant cells and participate in many biological functions. In this work, functional characterization of the Arabidopsis thaliana anion channel AtALMT10 has been initiated. Contrary to the Slow-type AtSLAH1 and AtSLAH3 channels, whose root gene expression is strongly repressed by water deficit (WD), salt stress and exogenous application of the phytohormone abscisic acid, the AtALMT10 gene is specifically induced by WD. To better understand the biological role of AtALMT10, the almt10-1 and almt10-3 mutant lines were segregated and genotyped. Both knockout mutants showed higher Cland lower NO3- content in the xylem sap and in shoot tissues respect to the Col-0 wild-type, suggesting a role of AtALMT10 in the regulation of Cland NO3- homeostasis. We are currently working on the tissuespecific and subcellular location of AtALMT10. This gene is of interest at both the research and agronomic levels given its potential relevance on the regulation of plant nutrition of essential elements and the plant response to abiotic stress.

El cloruro es un micronutriente esencial que tradicionalmente se ha considerado perjudicial para la agricultura por su efecto tóxico en salinidad y por competir con el nitrato. Sin embargo, recientemente hemos descubierto que la fertilización con cloruro confiere unas funciones beneficiosas para las plantas, cuando el cloruro se acumula en hoja a niveles típicos de un macronutriente. Entre los efectos positivos destacan la estimulación del crecimiento, mayor rendimiento fotosintético, menor gasto de agua gracias a un consumo más eficiente y una mayor resistencia a sequía. Además, la fertilización con cloruro mejora la eficiencia en el uso del nitrógeno y reduce la acumulación de nitrato en hoja, generando beneficios para una agricultura más sostenible y resiliente, y un consumo más saludable