Browsing by Author "Massa, Anabella"
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- Assessment of cyanobacterial biomass as sustainable agricultural fertilizer: soil experiment with plants in Pot †Publication . Massa, Anabella; Azevedo, Joana; Azevedo, Rui; Pinto, Edgar; Costa, Anabela; Vasconcelos, Vitor; Campos, Alexandre; Freitas, MarisaProviding food to the growing human population in a sustainable way is one of the greatest challenges of modern society. In this context, cyanobacterial biomass (CB) can function as a source of macronutrients to increase soil productivity. These organisms can be collected from the environment in considerable amounts, since they tend to grow in large blooms. However, some of these cyanobacterial strains produce toxins that need to be carefully monitored to avoid food accumulation. The objective of this work was to evaluate the possible use of toxic and non-toxic strains of CB as fertilizer supplement in the growth of economically relevant vegetables. One-month old Raphanus sativus (radish) and Spinacia oleracea (spinach) plants were grown in pots in indoor controlled conditions. Six experimental conditions were set: (1) a control with no nutrient addition, (2) a recommended dose of a NK commercial fertilizer (CF), 0.6g of lyophilized CB of (3) a non-toxic strain of Cylindrospermopsis raciborskii, (4) a toxin-producing strain of C. raciborskii, (5) Microcystis aeruginosa, and (6) Anabaena sp. Several variables were estimated: in CB, this included the NPK dose addition, and in plants, the height, dry weight (dw) of the shoot and root, and the mineral content of plant edible parts. The mineral content in CB was estimated and compared with the recommended dose of CF, according to the information given by the fabricant label. We found no significative differences in N composition; nevertheless, there was a significative higher content in P and significative lower content in K in the CB. In the plants, we found no significative statistical differences between the treatments for the dw of radish root and spinach height. In spinach, the dw of the shoot in the M. aeruginosa treatment was significantly lower than the control, CF, and both the toxic and non-toxic C. raciborskii biomass. Additionally, in radish, the plant height and dw of the shoot M. aeruginosa treatment were significantly lower than in the toxic strain of C. raciborskii treatment. When analyzing mineral content in edible parts, we found that spinach treated with control and CF showed a higher content of Ca, Mo, N, P, and K, while in radish, the same two treatments plus the C. raciborskii toxic had higher Co and Fe content. M. aeruginosa amendment seems to impair shoot growth in both plant species. On the contrary, the toxic C. raciborskii CB seems to have a beneficial effect on growth and in mineral uptake on radish plants.
- Cyanobacterial biomass used as biofertilizer in lettuce plants: effects on growth and cyanotoxin accumulation †Publication . Santos, Érica; Massa, Anabella; Azevedo, Joana; Martins, Diogo; Reimão, Mariana; Vasconcelos, Vitor; Campos, Alexandre; Freitas, MarisaThe use of cyanobacterial biomass as a biofertilizer is promising in terms of sustainable agriculture. Nevertheless, cyanobacteria can be considered a threat to human and environmental health due to the potential presence of cyanotoxins, since some studies report that the use of contaminated water for agricultural irrigation can impair plant growth and lead to contamination of food products. Interestingly, at environmentally relevant concentrations, cylindrospermopsin (CYN) seems to cause no deleterious effects in plants, and it might even promote their yield. However, studies assessing CYN accumulation in the edible tissues at environmental concentrations are lacking. The objective of this work was to evaluate the effects of cyanobacterial biomass CYN producing or non-producing on lettuce plant growth, and that of CYN accumulation in edible tissues. This study consisted of growing lettuce plants, under controlled conditions, for 25 days in soil (1) with no extra nutrient addition (control) and supplementation with (2) cyanobacterial biomass that did not produce CYN, (3) cyanobacterial biomass that produced CYN (~10 µg of dissolved CYN), and (4) cyanobacterial biomass that produced CYN, treated by boiling for 5 min (~25 µg of dissolved CYN). At the end of the exposure, lettuce growth was assessed, as well as CYN accumulation in tissues and soil. The results showed that leaf growth was significantly increased (p < 0.05) in lettuce plants supplemented with cyanobacterial biomass, especially at condition (3), which was five-fold higher compared with the control group. Regarding CYN accumulation, for conditions (3) and (4), the toxin was detected in the tissues of plants, as well as in soil at the following decreasing order of concentrations: soil > roots > leaves. Interestingly, the concentration determined in lettuce leaves in condition (4) was three-fold lower when compared with the condition (3). Nevertheless, for both conditions, although CYN has been detected in lettuce leaves, the concentration in the edible part did not exceed the proposed provisional tolerable daily intake (TDI) of 0.03 µg/kg/BW. In conclusion, these results suggest that the use of cyanobacterial biomass as lettuce biofertilizer, even containing CYN at environmentally relevant concentrations, can positively influence plant growth and development without compromising the safety of edible tissues.
- Determination of Vitamin C content in spinach plants grown under the use of cyanobacteria biomass as fertilizerPublication . Martins, Diogo; Massa, Anabella; Reimão, Mariana; Vasconcelos, Vítor; Campos, Alexandre; Pinto, Edgar; Freitas, Marisa; REIMÃO BORGES LOPES DA SILVA, MARIANA; Pinto, Edgar; Freitas, MarisaThe agricultural sector is continuously exploring sustainable and innovative approaches to enhance crop productivity, driving the quest for greener alternatives over synthetic fertilizers. Cyanobacteria have been reported as a promising agricultural fertilizer, with positive effects on crop yield. However, little is known about its potential effects on the produced vegetables' nutritional quality. Studies have documented that exposure of plants to cyanobacterial crude extracts stimulates the production of enzymatic and non-enzymatic antioxidants. Vitamin C, a non-enzymatic antioxidant, plays a crucial role in protecting cells from oxidative stress and spinach is known to be relatively high in vitamin C compared to other vegetables. The purpose of this study was to determine the content of vitamin C in spinach plants grown under the use of cyanobacterial biomass as fertilizer. Spinach plants were tested in soil, under six different conditions: (i) control, (ii) commercial chemical fertilizer, cyanobacterial biomass (iii) non-cyanotoxin producer, and cyanotoxin producer of (iv) Anatoxina (ANA), (v) Microcystin (MC), and (vi) Cylindrospermopsin (CYN). The analysis of vitamin C in spinach plants was performed according to EN 14130:2003. The results showed an increased content of vitamin C in all exposed groups when compared to the control (37 mg/Kg), with statistical differences in the conditions exposed to MC (56 mg/kg), ANA (76 mg/kg), and CYN (114 mg/kg). The results suggest that the rise in vitamin C may be related to a plant defence mechanism against oxidative stress potentially generated by exposure to cyanotoxins. Although the antioxidant content in spinach plants can be enhanced as a mechanism to cope with oxidative stress, prolonged exposure may increase plants' susceptibility to accumulate cyanotoxins, which may pose a risk to human health. Additional studies are needed to understand all the positive and negative effects of using cyanobacteria biomass as a biofertilizer.
- Toxic and non-toxic cyanobacterial biomass as a resource for sustainable agriculture: A lettuce cultivation experimentPublication . Massa, Anabella; Santos, Érica; Martins, Diogo; Azevedo, Joana; Reimão, Mariana; Almeida, Agostinho; Azevedo, Rui; Pinto, Edgar; Vasconcelos, Vítor; Campos, Alexandre; Freitas, MarisaCyanobacteria represent a promising resource for sustainable agriculture, as they have demonstrated the ability to restore soil fertility even after death and decay. However, several cyanobacteria can also release secondary metabolites, such as cyanotoxins, which may compromise the quality of agricultural products and pose a potential risk to human health. Depending on the concentration of exposure, few studies reported deleterious effects on plant species when irrigated with cylindrospermopsin (CYN) contaminated water, impairing plant growth and leading to food product contamination, while other studies show promoting effects on plant yield. To evaluate the potential of cyanobacterial biomass (cyanotoxin-containing or not) as a sustainable resource for soil amendment, biostimulants or fertilizers for lettuce cultivation, a study was carried out that consisted of the culture of lettuce plants under controlled conditions, in soil: (1) with no extra nutrient addition (control) and supplemented with 0.6 g of freeze-dried Raphidiopsis raciborskii biomass of (2) a non-CYN-producing strain, (3) a CYN-producing strain, and (4) the same CYN-producing strain pasteurized. Results showed no significant differences in photosystem II efficiency with the amendment addition. On the contrary, shoot fresh weight significantly increased in lettuce plants grown with the cyanobacterial biomass addition, especially in condition (3). In addition, there were significant differences in mineral concentrations in lettuce leaves after the cyanobacterial biomass addition, such as K, Na, Ca, P, Mg, Mn, Zn, Cu, Mo, and Co. CYN accumulation was detected under conditions (3) and (4), with concentrations observed in descending order from roots > soil > shoot. Nevertheless, the CYN concentration in edible tissues did not exceed the WHO-proposed tolerable daily intake of 0.03 μg/kg/day. These findings suggest that incorporating cyanobacterial biomass as a soil amendment, biostimulant or fertilizer for lettuce cultivation, even with trace amounts of CYN (1–40 μg/g), may enhance plant yield without leading to cyanotoxin accumulation in edible tissues above the WHO-recommended tolerable daily intake.