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The aim of this work was to study the influence of salinity of the fertigation solution on the vegetative growth, as well as on the osmolytes and chloride concentration of four halophytic species. ...

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 &times, wittrockiana (pansy) were grown in a greenhouse and five fertigation treatments were applied: W9.0 (pure wastewater, EC 9.0 dS m&minus, 1), W4.5 (diluted wastewater, EC 4.5 dS m&minus, 1), DW4.5 (depurated wastewater, EC 4.5 dS m&minus, 1), PW4.5 (phytodepurated wastewater, EC 4.5 dS m&minus, 1), and T (tap water, control, EC 1.5 dS m&minus, 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&minus, 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 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.

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&minus, 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&minus, 1 and the silicon concentration was 150 mg L&minus, 1. Foliar spraying was applied weekly. Pelargonium can be grown in moderately saline irrigation water (3.0 dS m&minus, 1). This bedding plant mitigates salt stress by avoiding the uptake of Cl&minus, 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&minus, 1).

Salinity is one of the environmental factors inhibiting productivity in crop plants. Available strategies to mitigate the abiotic stresses are limited. Microalgae and cyanobacteria can mitigate the adverse effects of abiotic stress due to their biostimulant properties. The aim of this work was to study the effect of hydrolysate of the ciyanobacterium Arthrospira platensis on the growth of Petunia plants under salt stress conditions over two growing seasons (winter and spring). Plants were exposed to 2.0, 2.5, and 3.0 dS m−1 EC, with and without application of A. platensis hydrolysate. At the end of the trial, biometric parameters and plant analysis were determined. Petunias had a negative response when the salinity level rose from 2 to 3 dS m−1 and exhibited moderate tolerance to high internal Na and Cl concentrations. Results show that a high salinity reduces the Ca, Mg, K, and S contents in the leaves and provokes a sharp reduction in the K+/Na+ relationship. Applying A. platensis hydrolysate alleviates the effects of NaCl stress and stimulates shoot and bud formation in the petunia mother plant while inducing flowering in commercial Petunia plants. The A. platensis hydrolysate application increased the K+/Na+ relationship in treatments with an EC of 3.0 dS m−1.

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 &times, wittrockiana Gams. (pansy), to detect possible harmful impacts on plants. The treatments tested were: W9.0 (pure wastewater, EC 9.0 dS m&minus, 1), W4.5 (diluted wastewater, EC 4.5 dS m&minus, 1), DW4.5 (depurated wastewater, EC 4.5 dS m&minus, 1), PW4.5 (phytodepurated wastewater, EC 4.5 dS m&minus, 1), and T (tap water, the control, EC 1.5 dS m&minus, 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&minus, 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&minus, 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.

The aim of this work was to assess the seed oils of different Borago species as sources of bioavailable γ-linolenic acid (GLA) by establishing its positional distribution within the triacylglycerol (TAG) structure. To this end, seeds of wild and farmed Borago species were collected and analysed. The highest GLA percentage of total fatty acids (FA) was found in B. morisiana and B. pygmaea (23.1 and 22.9% GLA of total FA, respectively). Other endemic Borago species (B. trabutii and B. longifolia) show a lower GLA content (18.9 and 19.0% of total FA, respectively). Oil content in seeds of B. officinalis ranged from 14.4 to 20.3%, while the GLA percentage of total FA was 15.7–19.4%, which leads to a 2.3–3.7% GLA range in the whole seeds. For endemic Borago, such amounts were 5.6, 5.0, 3.9, and 3.0%, for B. morisiana, B. pygmaea, B. trabutii, and B. longifolia, respectively. The distribution of FA in the sn-2 position of TAG was assessed by enzymatic hydrolysis reaction. The best regiospecific index was found in B. longifolia (0.8) and B. officinalis (1.0). This study provides useful data on novel GLA-rich Borago seed oils, which have potential use in the food and pharmaceutical industries.

Ammonium (NH4+) is an important nitrogen (N) source for plant growth. Nevertheless, NH4+–N can be oxidized to nitrate (NO3−) by nitrification and then nitrate and nitrite can be leached into ground...

The objective of this work is the development of empirical models that permit the prediction of the calcium (Ca) and magnesium (Mg) nutritional needs of Dieffenbachia amoena “Tropic Snow.” In order...

The sequential reuse of drainage water in greenhouse horticulture production to grow successively more salt tolerant crops is proposed as a sustainable alternative to recirculation systems when the irrigation water quality is low. This practice is known as Serial Biological Concentration or Integrated Farm Drainage Management. The objective of this assay was to assess the nutritional responses of Cordyline fruticosa var. ‘Red Edge’ (a semi-tolerant crop) fertigated with leachates from Citrullus lanatus (horticultural crop) cultivated on rockwool, compared to a conventional fertigation. Four treatments were tested: T1 (nutritionally balanced control or standard nutrient solution, with an electrical conductivity (EC) of 2.5 dS m−1); T2 (saline control; T2 diluted to an EC of 1.5 dS m−1, afterwards, NaCl was added to achieve 2.5 dS m−1); T3 (pure leachate from the hydroponic culture of C. lanatus), and T4 (diluted leachates, T3 diluted with irrigation water to 2.5 dS m−1). At the end of the trial, biometric parameters were determined and Na+, K+, Ca2+ and Mg2+ concentrations and the accumulation in photosynthetic organs (leaves), conductive organs (stems and petioles) and absorption organs (roots) were measured. The treatments tested had no effect on the number of leaves, leaf area per plant, leaf size, plant fresh and dry weight and shoot:root dry weight ratio. Nevertheless, the plants fertigated with pure leachates were significantly smaller. Regarding the plants’ fresh:dry weight ratio, this was significantly lower when plants were fertigated with pure leachates than with diluted leachates. The use of pure leachates does not cause an increment in total Na+ accumulation with respect to the nutritionally balanced control because Na+ concentration increases only in stems and petioles. Total K+ accumulation decreased when plants were irrigated with solutions with high concentrations of NaCl. The high Ca2+ concentration in the non-diluted leachate led to a high total Ca2+ accumulation. Total Mg2+ accumulation was affected negatively by Ca2+ uptake. It can be concluded that diluted leachates from C. lanatus can be used for the fertigation of C. fruticosa.

In closed soilless growing systems, leachates are used for the fertigation of the same culture, which is known as recirculation. This technology has been widely studied. It constitutes an environmentally friendly system because it prevents the leaching of chemicals into the environment, contributing to the sustainability of the horticultural sector. Nevertheless, the use of low quality water makes its application difficult. Moreover, as salinity increases in leachates, specific ions may become toxic or interfere with the uptake of other nutrients. In these situations, the sequential reuse of drainage waters to grow successively more salt tolerant crops, a practice which is known as Serial Biological Concentration or Integrated Farm Drainage Management, may be proposed. The aim of this trial was to assess the nutritional responses of Cordyline fruticosa var. ‘Red Edge’ (a semi-tolerant crop) fertigated with leachates from Citrullus lanatus cultivated on rockwool, compared with to conventional fertigation. There were 4 treatments: T1 (nutritionally balanced control or standard nutrient solution, with an electrical conductivity (EC) of 2.5 dS m−1), T2 (saline control; T2 diluted to an EC of 1.5 dS m−1; afterwards, NaCl was added to achieve 2.5 dS m−1), T3 (pure leachates from the hydroponic culture of C. lanatus) and T4 (diluted leachates, T3 diluted with irrigation water to 2.5 dS m−1). Dry weight (DW) and Cl−, N, P and SO42− concentrations as well as the extraction of photosynthetic organs (leaves), conductive organs (stems and petioles) and absorption organs (roots) were measured. The results obtained confirmed that diluted leachates can be employed for the fertigation of C. fruticosa ‘Red Edge’, because there were no effects on the plants DW, and no significant differences in Cl−, N, P or SO42− concentrations in leaves with respect to the nutritionally balanced control.

In horticultural practice accelerated plant development and particularly earlier flowering, has been reported with microalgae applications. Therefore, the objective of this work was to study the effects of foliar spraying with Scenedesmus sp. and Arthrospira platensis hydrolysates on Petunia x hybrida plant development and leaf nutrient status. Three treatments were tested: T1 (foliar application with water, the control), T2 (foliar application with Arthrospira), and T3 (foliar application with Scenedesmus). Foliar spraying was applied five times (0, 14, 28, 35, and 42 days after transplanting). The concentration of both microalgae was 10 g L−1. At the end of the trial biometric parameters and nutrient concentration in photosynthetic organs (the leaves) were measured. The results of this assay show that foliar application of Scenedesmus accelerated plant development in terms of higher rates of root growth, leaf and shoot development, and earliness of flowering. Arthrospira enhanced the root dry matter, the number of flowers per plant, and the water content. Nevertheless, a reduction was found in the conductive tissue (stem + petiole) dry weight with Arthrospira compared with Scenedesmus and the control. The results also show that microalgae hydrolysate supply can improve the plant nutrient status. Based on these results, it is advisable to use Scenedesmus hydrolysates in foliar applications to increase the blooming of Petunia x hybrida.

Aquaculture effluent can supply certain plant nutrients in adequate amounts. However, the nutrients present in the fish waste solution are not balanced. Mixing this effluent in an independent unit with a hydroponic nutrient solution can help to optimize conditions for the plants and minimize such drawbacks. The objective of this work was to assess the crop production and the nutritional responses of Pelargonium zonale fertigated with different percentages of fish wastewater. Five treatments were performed: 100NS, 75NS + 25AS, 50NS + 50AS, 25NS + 75AS and 100AS, where AS is the fish wastewater and NS a hydroponic nutrient solution. The species used to provide the fish waste solution was tilapia nilotica (Oreochromis niloticus). The results of this assay show that: i) fish wastewater can be utilized for the fertigation of Pelargonium zonale (a short-cycle crop) as there are no differences in the leaf, stem-petiole and flower dry matter, leaf water content, leaf area, plant height and leaf color compared to Pelargonium zonale fertigated with a chemical fertilizer; ii) the application of 75NS + 25AS accelerated flowers, shoots and leaves production. A higher percentage of fish waste solution mixed with the applied nutrient solution significantly reduces the K concentration in the nutrient solution and in the leaf; however, tilapia waste solution supplies adequate N, P and Ca nutrients to the pelargonium plants. Therefore, the reuse of fish waste solution can reduce the application rate of some inorganic fertilizers, which in turn can reduce the cost of fertilizers while preventing environmental pollution.

Fertigation practices have been proposed for decreasing nitrogen (N) leaching losses and for nutrient efficiency increase, including the use of nutrient solutions with low concentrations of N and the application of nitrification inhibitors with ammonium ammonium (NH4 +) N fertilizers. The effects of N form, application rates, and use of an inhibitor of nitrification [3,4- dimethylpyrazole phosphate (DMPP)] on the growth and the N percentages in leaves of Petunia × hybrida, as well as the N content in the substrate, were tested. Plants were placed in a venlo-glass greenhouse. Five treatments were established, changing N form, application rates, and with or without the inhibitor of nitrification: T1, 120 mg L−1 of N- nitrate (NO3 −); T2, 120 mg L−1 of N-NH4 +; T3, 80 mg L−1 of N-NH4 + with DMPP; T4, 120 mg L−1 of N-NH4 + with DMPP; and T5, 160 mg L−1 of N-NH4 + with DMPP. Nitrogen form did not have an effect on plant dry and fresh weight, plant height, or number of buds; however, ammonium treatments increas...

Nutritional solution composition in fertigation must be designed according to crop needs. These needs are variable and depend on factors like plant growth rate, environmental conditions, and water uptake. The objective of this work is to study the influence of the N-form supply (N-NO3– or N-NH4+) on the potassium uptake and potassium concentration changes on the recycled solution and the development of empirical models that permit the prediction of the potassium nutritional needs of Dieffenbachia amoena, ‘Tropic Snow’. To achieve this, potassium uptake has been correlated to temperature, vapor pressure deficit, global radiation, and leaf area index. The plants were placed in a Buried Solar Greenhouse, the plants being supplied with equal amounts of nitrogen, differing in the percentage of the N-form applied (NO3–:NH4+): Ta (100:0), Tb (50:50), and Tc (0:100). Seasons (winter and summer) generate important differences in the potassium concentration changes in the recycled solution but are not influenced by the nitrogen form. In winter, the potassium concentration remains constant, whereas in summer conditions, there is a higher decrease. This difference in behavior should be considered in the nutritive solution formulation. The nitrogen form applied does not affect potassium uptake. The study also indicates the possibility of predicting the potassium (K) uptake using the proposed models. K uptake can be estimated with a model dependent on the leaf area index, and potassium uptake concentration can be estimated with K uptake through the model and the experimental water uptake.