The effect of melatonin (MT) on potato plants under drought stress is still unclear in the available literature. Here, we studied the effect of MT as a foliar application at 0, 0.05, 0.1, and 0.2 mM on potato plants grown under well-watered and drought stressed conditions during the most critical period of early tuberization stage. The results indicated that under drought stress conditions, exogenous MT significantly (p ≤ 0.05) improved shoot fresh weight, shoot dry weight, chlorophyll (Chl; a, b and a + b), leaf relative water content (RWC), free amino acids (FAA), non-reducing sugars, total soluble sugars, cell membrane stability index, superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX) compared to the untreated plants. Meanwhile, carotenoids, proline, methylglyoxal (MG), H2O2, lipid peroxidation (malondialdehyde; MDA) and abscisic acid (ABA) were significantly decreased compared to the untreated plants. These responses may reveal the protective role of MT against drought induced carbonyl/oxidative stress and enhancing the antioxidative defense systems. Furthermore, tuber yield was differentially responded to MT treatments under well-watered and drought stressed conditions. Since, applied-MT led to an obvious decrease in tuber yield under well-watered conditions. In contrast, under drought conditions, tuber yield was substantially increased by MT-treatments up to 0.1 mM. These results may imply that under water deficiency, MT can regulate the tuberization process in potato plants by hindering ABA transport from the root to shoot system, on the one hand, and by increasing the non-reducing sugars on the other hand.

Table grape berries are classified as a perishable crop that deteriorates quickly after harvest. The application of melatonin after harvest was found to be effective for retarding senescence and slowing ripening. In the current study, we tested the influence of two melatonin concentrations (50 and 100 µmol) as a postharvest application on quality, bioactive compounds, and enzyme activities of grape berries cv “Crimson” stored at 0 ± 1 °C and 90% relative humidity (RH) for 35 days. Our results indicated that melatonin application extends the shelf-life of berries by reducing weight loss and maintaining total soluble solids (TSS), titratable acidity (TA), berry adherence strength, and firmness. Melatonin treatment also reduced pectin methyl esterase (PME) and polygalactouranase (PG) enzyme activities compared to the control. Moreover, O2•− and H2O2 rates in berries were reduced by high melatonin concentration. Moreover, peroxidase (POD) and catalase (CAT) enzyme activities were increased by melatonin application. Our findings suggested using melatonin postharvest to increase shelf life and maintain quality attributes during refrigerated storage, which could be advantageous on a large scale.

Catharanthus roseus is a medicinal plant that produces indole alkaloids, which are utilized in anticancer therapy. Vinblastine and vincristine, two commercially important antineoplastic alkaloids, are mostly found in the leaves of Catharanthus roseus. ĸ-carrageenan has been proven as plant growth promoting substance for a number of medicinal and agricultural plants. Considering the importance of ĸ-carrageenan as a promoter of plant growth and phytochemical constituents, especially alkaloids production in Catharanthus roseus, an experiment was carried out to explore the effect of ĸ-carrageenan on the plant growth, phytochemicals content, pigments content, and production of antitumor alkaloids in Catharanthus roseus after planting. Foliar application of ĸ-carrageenan (at 0, 400, 600 and 800 ppm) significantly improved the performance of Catharanthus roseus. Phytochemical analysis involved determining the amount of total phenolics (TP), flavonoids (F), free amino acids (FAA), alkaloids (TAC) and pigments contents by spectrophotometer, minerals by ICP, amino acids, phenolic compounds and alkaloids (Vincamine, Catharanthine, Vincracine (Vincristine), and vinblastine) analysis uses HPLC. The results indicated that all examined ĸ-carrageenan treatments led to a significant (p ≤ 0.05) increase in growth parameters compared to the untreated plants. Phytochemical examination indicates that the spray of ĸ-carrageenan at 800 mg L−1 increased the yield of alkaloids (Vincamine, Catharanthine and Vincracine (Vincristine)) by 41.85 μg/g DW, total phenolic compounds by 3948.6 μg gallic/g FW, the content of flavonoids 951.3 μg quercetin /g FW and carotenoids content 32.97 mg/g FW as compared to the control. An amount of 400 ppm ĸ-carrageenan treatment gave the best contents of FAA, Chl a, Chl b and anthocyanin. The element content of K, Ca, Cu, Zn and Se increased by treatments. Amino acids constituents and phenolics compounds contents were altered by ĸ-carrageenan.

Plant growth regulators can affect the primary and secondary metabolites of various plant species. However, the effect of paclobutrazol (PBZ) on the composition of lavender oil, especially related to the terpenoid pathway, is still unclear in literatures. In this study, the effect of PBZ as a foliar spray (0.200, 400 and 600 ppm) on the vegetative growth, phytochemical content, and both antioxidant and antimicrobial properties of lavender oil were investigated. The results indicated that all examined PBZ treatments led to a significant (p ≤ 0.05) decrease in growth parameters compared to the untreated plants. Meanwhile, the yield of essential oil was significantly decreased by the treatment of PBZ at 200 ppm compared to the control. In contrast, applied-PBZ significantly enhanced the chlorophyll content and displayed a marked change in the composition of the essential oil. This change included an obvious and significant increase in 3-carene, eucalyptol, γ–terpinene, α-pinocarvone, caryophyllene, β-vetivenene, β-santalol, ledol, geranyl isovalerate, farnesol, caryophyllene oxide, and phytol percentage. Generally, the highest significant values were achieved by the treatment of 400 ppm compared to the other treatments. Furthermore, this treatment showed the highest free radical scavenging activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) by 13% over the control. Additionally, to determine the antimicrobial activities of the extracted oil, each treatment was examined against two strains of Gram positive bacteria (S. aureus and B. cereus), two strains of Gram negative bacteria (S. enteritidis and E. coli), and two fungal species (C. albicans and A. niger) represent the yeast modal and filamentous fungus, respectively. The findings demonstrated that all examined species were more sensitive to the oil that was extracted from lavender plants, treated with 400 ppm PBZ, compared to the other concentrations.

Calla lily (Zantedeschia albomaculata (Hook.) Baill.) is an herbaceous or semi-evergreen perennial grown from rhizomes. It is commonly named “Spotted Arum”. Ribosomal RNAs (rRNAs) are found in all known organisms and are known for being functionally equivalent in all of them. A completely new in vitro culture protocol was applied to Z. albomaculata with two hormones, 6-Benzylaminopurine (BAP) and kinetin, to obtain full growth and multiplication. Due to their highly conserved sequences, the analysis of small-subunit rRNAs (16S–18S rRNAs) can provide precise statistical evaluation of a wide variety of phylogenetic connections. As a result, the plant’s 18S rRNA gene allowed for identification and partial sequencing. Also, the traditional floral method and the novel application technique for identification were applied to Z. albomaculata. In this paper we systemically describe the structural strategies of the plant’s adaptation to the surroundings at the morphological, physiological, and anatomical scale. Most the essential oils and fatty acids found in Z. albomaculata are omega fatty acids, octadecenoic acid, linoleic acid, and palmitic acid. All these fatty acids have industrial, medicinal, and pharmaceutical applications. The significant findings are the spadix sheathing leaves, and the precipitation of raphides calcium oxalate. The mitotic index showing the division activity was recorded, and it was 17.4%. The antimicrobial activity of Z. albomaculata ethanol extract was performed via the well diffusion method. This extract has shown high activity against Escherichia coli and Pseudomonas aeruginosa, compared to its lower activity against Bacillus cereus. By defining these characteristics and in vitro culture conditions, we will be able to acclimatize the plant in greenhouses, and then transfer it to the open field. The findings of this work identified the general characteristics of Zantedeschia albomaculata as an ornamental and medicinal plant in order to acclimatize this plant for cultivation in the Mediterranean climate.