In order to investigate the effects of dissolved humic acid (DHA) and tourmaline on uptake of 2, 2′, 4, 4′, 5, 5′- hexabrominated diphenyl ether (BDE-153) by Lactuca sativa, different fractions of ...DHA, including DHA1 and DHA4, as well as different doses of tourmaline were introduced into BDE-153 contaminated solutions for plant growth. The levels of BDE-153 in L. sativa tissues were positively correlated with the Fe levels (R2 = 0.9264) in seedings of the treatments with different doses of tourmaline. However, when adding DHA1 and DHA4 into the system, the correlation coefficients (R2) decreased to 0.6976 and 0.5451 from 0.9264, respectively. In contrast with the Fe contents, the presence of DHAs didn't affect the R2 between the levels of BDE-153 and the lipid contents in plant tissues. Our results indicated that both DHA1 and DHA4 could severely alter the BDE-153 uptake by L. sativa through reducing the Fe uptake instead of the lipid contents. Additionally, DHA4 exhibited much stronger abilities to alter the BDE-153 accumulation than DHA1. Transmission electron microscopy (TEM) observations indicated that either DHA1 or tourmaline or co-treatment with DHA and tourmaline had no negative impact on L. sativa at the cellular level. The present study provides important information for the impacts of different fractions of DHA extracted from soil on the BDE-153 migration in plant systems. Moreover, we elucidated the importance of the iron in tourmaline for migration of the polybrominated diphenyl ethers (PBDEs) in plant systems.
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•BDE-153 levels in L. sativa tissues positively correlated with Fe levels in seedings.•DHA1 and DHA4 decreased correlation coefficients between BDE-153 and Fe levels.•DHAs decreased correlation coefficients between BDE-153 levels and lipid contents.•DHA4 exhibited much stronger abilities to alter the BDE-153 accumulation than DHA1.•Either DHA1 or tourmaline had no negative impact on L. sativa at the cellular level.
DHA4 exhibited much stronger abilities to alter the BDE-153 accumulation than DHA1. The levels of BDE-153 in L. sativa tissues were positively correlated with the Fe levels (R2 = 0.9264) in seedings.
The aim of the study was to compare the effect of two leonardites (Humitec® and Humic Gold®) and an organic compost (Nutrimais®) with an untreated control on lettuce. The pot experiment was carried ...out in NE Portugal, in autumn 2019 and spring 2020. Humitec, Humic Gold and Nutrimais were applied alone or as a supplement to nitrogen (N), phosphorus (P) and potassium (K). The experiment was arranged as a three-factor experimental design (organic amendment, NPK addition and growing season). The growing season significantly influenced lettuce dry matter yield (DMY), the spring cycle being the highest yielding (10.6 to 6.5 g plant
−1
). NPK fertilization also significantly increased lettuce DMY (11.2 to 5.9 g plant
−1
). The organic amendment significantly influenced the concentration of some nutrients in plant tissues and some soil properties, but it did not influence lettuce DMY. In respect of growing season, Nutrimais increased lettuce DMY in the first one. In relation to the absence or otherwise of NPK fertilization, Nutrimais increased lettuce DMY in the pots not receiving NPK. Leonardites did not influence soil properties, tissue nutrient concentration or lettuce DMY. The positive effect on the lettuce DMY of organic compost was probably due to the supply of N, apparently the plants' most significant limiting factor. The non-positive results of leonardites were due to the fact that they neither provided N, nor enhanced its bioavailability from the soil. Thus, NPK fertilizer and Nutrimais, a compost of low C/N ratio, providing some N had the greatest effect on lettuce DMY.
ABSTRACT Iodine is essential to human metabolism, being fundamental in the production of the thyroid hormones. The consumption of biofortified foods can contribute to the increase of its intake. The ...objective of this study was to increase the iodine concentration in lettuce, also evaluating its effects on plant growth and production. The experiment was conducted in a greenhouse, in a hydroponic system of aerated static solution. A completely randomized design was used, in a 2 x 5 factorial scheme (variety x iodine dose), with three repetitions. Two lettuce varieties were used, the iceberg lettuce and the crispy leaf lettuce, submitted to five doses of iodine (0, 10, 20, 30 and 40 µmol L-1), having as source potassium iodide. At 40 days after transplantation, both cultivars were collected and evaluated for the weight of fresh and dry matter, iodine content and levels in the leaves and the root volume. With increased doses, the plants showed symptoms of phytotoxicity, resulting in lower productivity. However, all doses promoted elevations in the total iodine levels of plants. Therefore, it is possible to increase the iodine content in lettuce leaves, being necessary to adjust the doses to be used.
► In this manuscript, I described the in vitro kinetics of lettuce PPO with respect to oxygen using different substrates. ► I also investigated inhibition kinetics of WPC comparing with AA and ...cysteine on PPO activity. ► Potential use of WPC as nonhazardous antibrowning for food processing industries is strongly recommended.
The
in vitro kinetics of lettuce PPO with respect to dissolved oxygen using catechin, chlorogenic acid, caffeic acid and gallic acid has been examined.
In-vitro lettuce polyphenol oxidase (PPO) activity was determined by measuring the consumption of oxygen during the oxidation reaction. The effect of whey protein concentrate (WPC) was tested on the inhibition of lettuce PPO comparing with ascorbic acid (AA) and cysteine. A competitive model that considered inhibitors was the most appropriate model to explain reaction kinetics. Browning of lettuce was also monitored during storage for 24
h. Addition of WPC prevented loss of lightness in lettuce. Loss of identified phenolic compounds in lettuce was measured during the enzymatic browning process by high-performance liquid chromatography. Degradation of identified phenolic compounds followed first order kinetics during storage. Combination of WPC with cysteine was proposed for the protection of phenolics compounds against PPO-catalysed oxidation.
Nos últimos anos tem sido crescente as pesquisas científicas de inovação e tecnologia agrícola a respeito da ação do campo magnético sob a germinação e desenvolvimento de plantas. Diante do exposto, ...esta pesquisa teve como objetivo avaliar o desenvolvimento inicial de mudas de alface (Lactuca Sativa L.) com uso de água tratada magneticamente e não tratada (controle). O experimento foi realizado em bandejas de 120 células, sendo a parcela constituída por 12 células com 10 repetições, onde foram testados os tratamentos água tratada magneticamente e não tratada. Foram realizadas medições semanais de comprimento da parte aérea e quando as mudas atingiram 24 dias após germinadas, retirou-as das bandejas e avaliou-se os seguintes parâmetros: comprimento da parte aérea, massa seca da parte aérea, comprimento da raiz e massa seca da raiz. Nas condições de tempo de exposição e força do magnetizador, o uso da água magnetizada é benéfica para o alface e provavelmente para outras culturas. Em particular, para a alface, os resultados revelam que a irrigação com água tratada magneticamente é eficiente para obter-se mudas de alface com maior volume de biomassa na parte aérea e raiz.
The addition of green light-emitting diodes (LEDs) to a combination of red and blue LEDs, which promote photosynthesis and growth in plants, is known to enhance plant growth in closed-type plant ...production systems. However, there is limited information on the effects of supplementary green light. This study aimed to determine the effect of red (R), green (G), and blue (B) LED ratios on the growth, photosynthetic, and antioxidant parameters in two lettuce (
Lactuca sativa
) cultivars, red leaf ‘Sunmang’ and green leaf ‘Grand Rapid TBR’. The seedlings were grown for 18 days and then cultivated in growth chambers equipped with LED lighting systems for 4 weeks. Combinations of six LED lighting sources (R:B = 9:1, 8:2, 7:3; R:G:B = 9:1:0, 8:1:1, 7:1:2) were manufactured to emit red (655 nm), blue (456 nm), or green (518 nm) lights under photosynthetic photon flux density of 173 ± 3 μmol·m
-2
·s
-1
. Red LEDs were found to improve growth characteristics such as fresh and dry weights of shoots and roots, and leaf area in combination with blue LEDs. The substitution of blue with green LEDs in the presence of a fixed proportion of red LEDs enhanced the growth of lettuce. In particular, the fresh weights of red leaf lettuce shoots under R8G1B1 were about 61% higher than those under R8B2. Furthermore, analysis of leaf morphology, transmittance, cell division rate, and leaf anatomy under treatments with green LEDs supported the enhanced growth of the two lettuce cultivars tested. Meanwhile, growth under blue LEDs led to the accumulation of antioxidant parameters in ‘Sunmang’. Thus, the results of this study suggest that the percentage of red, green, and blue LEDs is an important factor for the growth, development, and biosynthesis of secondary metabolites in plants and especially the supplemental irradiation of green LEDs based on the combination of red and blue LEDs can improve lettuce growth.
Eighteen trials were carried out in a closed soilless system to evaluate the effectiveness of different strains of experimental non‐pathogenic Fusarium oxysporum and Fusarium solani, commercial ...biocontrol agents (Streptomyces griseoviridis, Bacillus subtilis and Beauveria bassiana), as well as products based on calcium oxide (CaO) and potassium phosphite on race 1 of Fusarium oxysporum f. sp. lactucae, the causal agent of the Fusarium wilt of lettuce. The treatments were applied to lettuce seedlings, which had been grown for 2 days in a peat medium before being artificially inoculated with the pathogen, and were repeated five times at 7‐day intervals. The experimental non‐pathogenic F. oxysporum MSA35 and FC3 strains provided a greater disease severity reduction (54%–83% efficacy) than the commercial B. subtilis (29%–31% efficacy), S. griseoviridis (22%–52% efficacy) and B. bassiana (39%–63% efficacy) formulations. The highest fresh weight value was provided by the non‐pathogenic F. oxysporum MSA35 and FC3 strains, thereby generally reflecting the observed disease reduction. Calcium oxide and potassium phosphite generally resulted in disease protection, but a great variability in efficacy was observed. The obtained results showed good possibilities for the non‐pathogenic Fusarium oxysporum strain against the pathogen in soilless systems.
•More balanced P budgets when using inputs with a flexible N:P stoichiometry.•High P surpluses when using compost and manure with a constrained N:P stoichiometry.•P budgets closer to P balance in ...grain as compared to vegetable production.•Cover crops could transfer 2–3kg Pha−1yr−1 to subsequent cash crops.
Inefficient phosphorus (P) use in intensive agriculture is common in both organic and conventional systems, resulting in P over-application and soil P build-up. Increasing crop P removal and P recycling within farming systems (e.g., via cover crops) and reducing P inputs lower P surpluses, resulting in more balanced P budgets. Lowering P inputs to reduce soil P surpluses is easier with mineral fertilizers for which nitrogen (N) and P inputs can be decoupled, whereas reducing inputs of organic amendments with a constrained N:P stoichiometry (manures, composts) often results in N under-fertilization and lower yields. We computed farm-gate P budgets for several vegetable and grain cropping systems in two long-term California agricultural experiments that vary in terms of inputs (mineral fertilizers, organic fertilizers, manure, yard compost), cash crops (corn, wheat, tomato, broccoli, lettuce), cover crops (type, frequency) and cropping intensity (biennially, annually or biannually). In organic systems, using manure or compost resulted in high P surpluses, whereas using pelleted or liquid organic fertilizers with higher N:P ratios resulted in smaller P surpluses. Systems receiving mineral fertilizers were often very close to P balance when fertilized regularly. Grain rotations generally had small P deficits whereas vegetable rotations had P surpluses due to lower crop P removal and higher output N:P in vegetables. Phosphorus uptake by cover crops was important (12–25kg Pha−1), but their benefits to soil fertility will depend on the magnitude and timing of P release during residue decomposition. Overall, using organic nutrient sources with a constrained stoichiometry and low N:P ratios resulted in significant P surpluses, confirming the need to use complementary N sources such as N-fixation or N-rich fertilizers to balance P budgets.
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