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The utilization of treated wastewater can enhance the crops’ irrigation efficacy by offering an extra source of water and nutrients for agricultural purposes. This methodology helps alleviate the pressure on conventional water resources and can be a sustainable strategy to address the challenges of water scarcity. However, it is essential to ensure that wastewater is properly treated to meet quality and safety standards before its application to agricultural crops. This study focuses on exploring the reuse of wastewater from microalgae production and its impact on Pelargonium × hortorum growth during two seasons (autumn and spring). The established treatments were as follows: tap water (control 1); 100% IW—inlet wastewater (control 2); 100% OW—outlet from the reactor; 75% OW + 25% W—75% outlet from the reactor and 25% tap water; and 50% OW + 50%W—50% outlet from the reactor and 50% tap water. Irrigation with wastewater in autumn did not have a significant negative effect (p > 0.05) on plant height, plant diameter, leaf dry weight, roots, or total dry weight, and it was comparable to the control in all applied percentages. On the other hand, wastewater irrigation during spring had a meaningful positive (p < 0.05) impact on plant growth compared to the control. These wastewater resources have a high concentration of nutrients, making them a valuable source of essential and/or beneficial elements. The levels of nutrients such as NO3− range from 144.08 ppm to 82.10 ppm, PO43− ranges from 14.14 ppm to 7.11 ppm, and K+ ranges from 36.83 ppm to 29.71 ppm. Therefore, the obtained results support the viability and effectiveness of using wastewater after microalgae production in agriculture to reduce water demand, mitigate water pollution, and substitute chemical fertilizer input, contributing to more sustainable agricultural practices. These results, with more detailed evaluations, would be applicable to other related plant species and are even applicable to the commercial production sectors.

The extraction method used to obtain biologically active compounds from microalgal biomass may affect the biostimulant capacity of the microalgae. The objective of this assay was to determine the most efficient extraction method to release the active components of the biomass of Chlorella vulgaris (C. vulgaris). Plantlets of Pelargonium × hortorum were grown in a greenhouse and five treatments were applied: C-application with water; M-application with untreated C. vulgaris microalgae; M-US-application with C. vulgaris microalgae treated with ultrasound; M-USHY-application with C. vulgaris microalgae treated with ultrasound and enzymatic hydrolysis; and M-USHYAU-application with C. vulgaris microalgae treated with ultrasound, enzymatic hydrolysis, and autoclaving. All microalgae treatments increased shoot number and stem and plant diameter. The US-treated biomass increased the inflorescence of the plant significantly compared to the control. To extract bioactive compounds from eukaryotic microalgae for plant biostimulating purposes, the US-treatment (or any other method damaging the plasma membrane) of microalgae cell is, or seems to be, suitable.. Macronutrient content in leaves was not affected by the microalgae treatment, except for K.

Strategies to prevent postharvest losses include the use of genotypes that have a longer life. The objective of this study was to develop a screening test for the estimation of cut flower postharvest life and the response to exogenous ethylene of different carnation cultivars at an early stage of plant growth. Ethylene sensitivity and production in different cut flower cultivars was evaluated, and a similar response in the vegetative stage was studied. Also, the possible relationship between the morphological parameters of cuttings and flower postharvest life was studied. Ethylene production of cuttings may be a useful tool for estimating ethylene production of cut flowers. There is a strong relationship between cut flower vase life and the root length of cuttings, as well as cut flower ethylene sensitivity and the number of internodes the cuttings have. Applications of exogenous ethylene to cutting cultivars have an effect on the growth parameters of the cuttings, but the response to ethylene in cut flowers does not behave in the same way in the vegetative stage.

The rapid development of greenhouse horticulture has brought about a dramatic increase in the nitrate pollution of aquifers. The optimization of nitrogen application is an important tool to minimize nitrogen losses. The objective of this research was to assess the effect of different fertigation strategies, based on the reduction of the nitrogen applied and the use of a percentage of NH4+ as a nitrogen source, on the decrease in the environmental impact caused by the traditional system, as well as to evaluate if this is compatible with a high fruit yield (considering quantity and quality). Lycopersicum esculentum Mill cv. Forteza plants were grown in a polyethylene greenhouse. Tomato yield and quality were evaluated, along with leachates, which were collected by means of rigid plastic lysimeters. The proposed strategies did not reduce fruit yield. However, the reduction in the nitrate applied caused firmness and °Brix decrease, together with a diminution in titratable acidity until 124 days after transplanting. Nevertheless, these effects were not observed with the replacement of some of the NO3− by NH4+. The reduction in fertilizer inputs significantly improved water and nutrient (N, P and K) use efficiency. The treatment with NH4+ improved K use efficiency, compared to the conventional treatment, but P decreased. The highest NO3− and K leaching was detected in the traditional treatment.

Landfill leachate can release pollutants into the environment. Nevertheless, it can be treated using a phytodepuration system via constructed wetlands to reduce contaminants. Moreover, this leachate can also increase the availability of macro and micronutrients in soil and water. In this trial, the reuse of untreated and treated wastewater from municipal solid waste (MSW) for fertigation was assessed. Plantlets of Viola × wittrockiana (pansy) were grown in a greenhouse and five fertigation treatments were applied: W9.0 (pure wastewater, EC 9.0 dS m−1), W4.5 (diluted wastewater, EC 4.5 dS m−1), DW4.5 (depurated wastewater, EC 4.5 dS m−1), PW4.5 (phytodepurated wastewater, EC 4.5 dS m−1), and T (tap water, control, EC 1.5 dS m−1). The treatment with untreated wastewater had a negative effect on plant dry weight, leaf size, specific leaf area, water content, and the number of closed and open flowers, due to the high concentration of SO42− in the fertigation water. It also reduced the content of Cu, Mn, Fe, and Zn with respect to the control, because of the dry biomass diminution. Conversely, fertigation with phytodepurated wastewater enhanced root and shoot dry weight, water content, and the number of closed and open flowers. Cu and Mn contents in flowers surpassed the content detected in plants fertigated with untreated leachates. These findings demonstrate that phytodepurated wastewater obtained from MSW can be employed for the fertigation of this species.

The disposal of municipal solid waste (MSW) in landfills might result in serious environmental pollution. The goal of the present assay was to assess if MSW wastewater (pure or treated) can be used as a potential source for fertilizers, studying its effects on plant biometric parameters as well as on anion concentrations and anion partitioning of the bedding plant Viola × wittrockiana Gams. (pansy), to detect possible harmful impacts on plants. The treatments tested were: W9.0 (pure wastewater, EC 9.0 dS m−1), W4.5 (diluted wastewater, EC 4.5 dS m−1), DW4.5 (depurated wastewater, EC 4.5 dS m−1), PW4.5 (phytodepurated wastewater, EC 4.5 dS m−1), and T (tap water, the control, EC 1.5 dS m−1). The treatment with pure wastewater negatively affected plant fresh weight, water content (on a fresh weight basis), leaf area, plant height and width, and the number of leaves and flowers due to an accumulation of SO42− in plant tissues. Phytodepurated wastewater improved plant fresh weight, water content, plant height and width, the number of leaves and flowers, and reduced the leaf area because this treatment decreased SO42− concentrations in wastewater by half. Pansy plants also showed high levels of nutrients (N, P, and Mg) when compared with fertigation with pure and diluted landfill leachate. These results show that phytodepurated wastewater from MSW can be used for the fertigation of pansy plants.

Plant growth is limited by salinity stress. There are few strategies for alleviating it although Arthrospira platensis and silicon can stimulate plants to grow under stress conditions. The aim of this work was to study the effects of both a single and a joint application of Arthrospira platensis and silicon on the growth of Pelargonium hortorum L.H. Bailey under salt stress conditions. Plants were exposed to 2.0, 3.0, and 3.5 dS m−1 EC (electrical conductivity), with and without the application of microalgae and silicon. At the end of the trial, the biometric parameters and the plant analysis were determined. The microalgae hydrolysate concentration was 5 g L−1 and the silicon concentration was 150 mg L−1. Foliar spraying was applied weekly. Pelargonium can be grown in moderately saline irrigation water (3.0 dS m−1). This bedding plant mitigates salt stress by avoiding the uptake of Cl− ions and by tolerating a high Na+ concentration in the tissue. The joint foliar application of Arthrospira microalgae and silicon stimulates root, shoot, leaf, and flower formation in the Pelargonium hortorum L.H. Bailey crop under salinity conditions (3.5 dS m−1).

Abstract Microalgae like Chlamydomonas are beneficial organisms employed as biological stimulants to improve plants’ growth, fruit quality, and stress tolerance. In the current study, the effects of Chlamydomonas sp. foliar spraying (0, 20, and 40 ml L−1) were assayed on Camarosa strawberry plants under salinity stress (0, 40, and 80 mM NaCl). The results showed that the foliar application of Chlamydomonas extract influenced strawberry’s morphological, physiological, and biochemical characteristics under salinity stress. Foliar treatment of Chlamydomonas extract with and without salinity stress increased the leaf number and leaf area, the leaf relative water content, and photosynthetic pigments content. Moreover, the foliar application of Chlamydomonas extract decreased lipid peroxidation and hydrogen peroxide content and, on the other hand, enhanced the antioxidant enzymes activity (superoxide dismutase, guaiacol peroxidase, and peroxidase), phenolics, flavonoids, and anthocyanins content under salinity stress. For instance, the highest total antioxidant capacity was found in the plants foliar treated with 40 ml L−1 of Chlamydomonas algae extract under 80 mM salinity stress, which increased by 102.4% compared to the controls, as well as the highest total phenolic compounds and anthocyanin’s content were 30.22, and 7.2% more than the control plants, respectively. Overall, the foliar application of Chlamydomonas algae extracts, especially at a concentration of 20 ml L−1 enhanced the strawberry’s growth, yield, and physiological traits under saline conditions. The results with more detailed evaluations will be advisable for the pioneer farmers and extension section.

Agricultural residues adequate managing contributes to reduce CO2 emissions and easy the circular economy. In this paper, cucumber, tomato and pepper greenhouse crop residues were characterized both chemically and energetically to potential of waste as a biofuel. When compared to other herbaceous and woody biomass, the data show higher moisture, ash and chlorine contents. The gross calorific values of these residues are in the same range as the herbaceous biomass (14.92 MJ/kg), with net values of 13.71, 14.58 and 15.73 MJ/kg for cucumber, tomato and pepper, respectively. The study also included other not common elements, finding the highest values for calcium (13–25 mg/kg) and potassium (23–30 mg/kg). To date, empirical correlations have been defined to predict the CV as a function of total C content (expressed as % in dry weight) for these residues individually. The empirical correlations obtained had maximum absolute errors (MAE) of 0.11, 0.32 and 0.58 % for cucumber, tomato and pepper whereas the marginal mean bias errors (MBE) were 0.016, 0.002 and 0.004 %, respectively, which confirms the value of using this method to determinate the gross calorific value of these residues. The correlations shown provide a useful tool for developing energy production processes based on crop residues, that would appear to be an interesting source of renewable energy to produce heat.