The Content of Phenolic Compounds and Organic Acids in Two Tagetes patula Cultivars Flowers and Its Dependence on Light Colour and Substrate

The main focus of the study was to determine the content of phenolic acids, flavonoids, and organic acids in the flowers of Tagetes patula ‘Petite Gold’ and ‘Petite Orange’. The growth of the plants was assessed depending on the cultivation conditions. The above plants were illuminated with white light, whereas the ‘Petite Gold’ ones with white light enhanced with blue or red light. Both cultivars grew in a two-level-mineral compounds organic substrate. The research showed that the French marigold flowers were rich in phenolic compounds and organic acids. The ‘Petite Gold’ flowers had more bioactive compounds compared with the ‘Petite Orange’ flowers. Three flavonoids, 10 phenolic acids and seven organic acids were found in the ‘Petite Gold’ flowers. The artificial lighting used during the cultivation of the plants showed diversified influence on the content of organic compounds in their flowers. The measurements of the plants’ morphological traits and the number of inflorescences showed that illumination with red light resulted in a better effect. Large plants with numerous inflorescences grew in the substrate with a lower content of nutrients.

Changes in Metal Distribution, Vegetative Growth, Reactive Oxygen and Nutrient Absorption of Tagetes patula under Soil Cadmium Stress

Phytoremediation with hyperaccumulator plants has been recognized as a potential way for the clearing of cadmium (Cd)-contaminated soil. In this study, hyperaccumulator Tagetes patula was treated with seven concentrations of Cd, ranging from 0 to 300 mg kg−1. The Cd enrichment and nutrient contents in different organs during different growth phases were investigated. Under Cd concentrations ≤75 mg kg-1, the morphological growth of T. patula did not change significantly regardless of growth stage. However, when Cd concentration exceeded 150 mg kg−1, the morphological growth was remarkedly inhibited. The root/shoot ratio remained unchanged except for at 300 mg kg−1. In addition, Cd negatively influenced the flowering process at the concentration of 300 mg kg−1. Cd content increased significantly in Cd-treated plants. Nitrogen absorption was increased under Cd treatments, and phosphorus content was also increased under concentration ≤150 mg·kg−1. However, the potassium content in the flower was decreased under 300 mg kg−1. Furthermore, the contents of H2O2, O2− and malondialdehyde were increased during the seedling phase, especially when Cd concentration was ≥150 mg kg−1. In summary, T. patula showed a strong ability to tolerate Cd, and such ability might be explained by nutrient absorption and reactive oxygen clearness.

Biologicals and New Generation Fungicides in the Management of Blast Disease in Rice

Background: Blast is a devastating disease in rice production. The current research tested the efficacy of biologicals and fungicides against blast. Aqueous extracts of Azadirachta indica, Ocimum basalicum, Cymbopogan flexousus, Thymus vulgaris, Aloe vera, Tagetes patula, Cordia curassavica, Aegle marmelos, Allium fistulosum, Syzygium aromaticum, and Calotropis gigantea were tested in vitro at 5, 10, and 15% concentrations against Magnaporthe oryzae. Also, two isolates, Bacillus cereus OG2L and B. subtilis OG2A, and one isolate, Azotobacter SAG19, and, similarly, five new generation fungicides were evaluated at three different doses against blast pathogen M. oryzae in vitro. The treatments that exhibited the best performance in vitro were further evaluated against blast disease under field conditions.Results: Extracts of T. patula (5%), C. gigantea (5%), C. curassavica (10%), A. fistulosum (10%), and A. marmelos (15%) showed greater than 81% inhibition to M. oryzae in vitro. Likewise, all three biocontrol agents, viz. B. cereus OG2L, B. subtilis OG2A, and Azotobacter SAG19, demonstrated more than 50% inhibition of mycelial growth of pathogen in vitro, and the commercial formulations of fungicides Propineb, Trifloxystrobin+Tebuconazole, Tebuconazol+Triadimenol, Bacillus subtilis Strain QST 713, and Cinnamon Oil 8%+Clove Oil 2% also significantly inhibited M. oryzae. Under field conditions, C. curassavica (10%), A. marmelos (15%), C. gigantea (5%); B.cereus OG2L; B.subtilis OG2A; Proineb and Trifloxystrobin+Tebuconazole were effective in reducing disease in addition to yield enhancement.Conclusion: Overall, the plant extracts (C. curassavica at 10%, A. marmelos at 15%, C. gigantea at 5%); bio-agents (B. cereus OG2L, B. subtilis OG2A both at 2g/l), and new generation fungicides Antracol 70WP (Proineb) at 2.5 g/l and Nativo 75 WG (Trifloxystrobin+Tebuconazole) at 0.5 g/l provided effective control against blast disease and superior plant growth and yield compared with other treatments and untreated control.

Humic acids impact on heavy metal phytoextraction in Tagetes patula L.

In a model study, we analysed the impact of humic acids (HAs, 500 ppm) on the accumulation of heavy metals (HMs; Pb, Cu, Ni and Zn) in roots and aboveground organs of the annual ornamental plant Tagetes patula (Scarlet variety) cultivated on the Terra Vita nutritive substrate used in modern cultural landscape mulching to imitate the upper fertile root layer (UR-RAT) of contaminated urban soils in megacities. Plants were grown in full photoculture (at no sunlight) in pots placed in a closed grow box, maintaining internal microclimate. A modern HLG Quantum Board QB288 V2 Rspec LED panel enabled with vegetation modes was used as light source. HMs were introduced in substrate as aqueous saline. Each setting was quadruplicated. Total experiment duration was 30 days. Tagetes patula was proved a particularly effective phytoextractor of Zn applied at 40 mg/kg (p<0.01). At the same time, the plants showed high tolerance to toxic growth inhibition (in biometry of the above- and underground organ length and mass) and preserved external aesthetics. Metals were further graded by phytomass accumulation as follows: Cu>Pb>Ni. Ni at 30 mg/kg had a major impact on plant weight and length, which sets off the variety as a sensitive phytoexcluder for this metal. HAs increased aboveground mass in all settings and decreased the HM mass impact. A sharp root mass reduction was observed in combinations of the two factors (HMs+HAs), which was clearly reflected in impaired root mass in zinc settings. A single metal addition reduced the mass by average 12.0 % (p<0.01) vs. control (no HAs or HMs), whilst a combined HAs+HMs administration induced its 65.0 % reduction (p<0.01). The results obtained indicate a good root buffering capacity for HM translocation from the rhizosphere to aboveground parts. In general, HA usage is promising for creating the green space and phytoremediation of urban HM-contaminated soils.

Alleviation of Nematode-Mediated Apple Replant Disease by Pre-Cultivation of Tagetes

Apple replant disease (ARD) is a severe problem in orchards and tree nurseries caused by yet unknown soil biota that accumulate over replanting cycles. This study tested the contribution of nematodes to ARD, and cultivation of Tagetes as a control option. In a pot experiment, Tagetes patula or Tagetes tenuifolia were grown in ARD soil, incorporated or removed. Nematodes extracted from untreated ARD soil and washed on 20-µm sieves induced ARD symptoms when inoculated to apple plantlets growing in a sterile substrate. In contrast, nematodes from Tagetes treated ARD soil did not reduce root growth compared to uninoculated plants, irrespective of Tagetes species and incorporation. In plots of five apple tree nurseries or orchards, either Tagetes or grass was grown on ARD soil. Nematodes extracted from the grass plots and inoculated to apple plantlets significantly reduced plant growth compared to nematodes from Tagetes plots for all five farms. Apple rootstocks showed overall a significantly higher increase in shoot base diameter when grown on Tagetes-treated plots compared to grass plots, while this effect differed among farms. Plant-parasitic nematodes were too low in abundance to explain plant damage. In conclusion, Tagetes alleviated ARD by changing the nematode community in soil.

Alleviation of Nematode-Mediated Apple Replant Disease by Pre-Cultivation of Tagetes

Apple replant disease (ARD) is a severe problem in orchards and tree nurseries caused by yet unknown soil biota that accumulate over replanting cycles. This study tested the contribution of nematodes to ARD, and cultivation of Tagetes as a control option. In a pot experiment, Tagetes patula or Tagetes tenuifolia were grown in ARD soil, incorporated or removed. Nematodes extracted from untreated ARD soil and washed on 20 &micro;m-sieves induced ARD symptoms when inoculated to apple saplings growing in a sterile substrate. In contrast, nematodes from Tagetes treated ARD soil did not reduce root growth compared to uninoculated plants, irrespective of Tagetes species and incorporation. In plots of five apple tree nurseries or orchards, either Tagetes or grass was grown on ARD soil. Nematodes extracted from the grass plots and inoculated to apple saplings significantly reduced plant growth compared to nematodes from Tagetes plots for all five farms. Apple rootstocks showed overall a significantly higher increase in shoot base diameter when grown on Tagetes-treated plots compared to grass plots, while this effect differed among farms. Plant-parasitic nematodes were too low in abundance to explain plant damage. In conclusion, the free-living nematodes involved in ARD can be controlled by Tagetes.