Turkey is one of the most important centres of mulberry genetic resources and mulberries grow naturally almost everywhere in Turkey. This study was carried out to determine the most important phenolic compounds and phytochemical properties of mulberry ( Morus nigra L.) genotypes collected from natural resources in 2016-2017 in the province of Uşak (Turkey). The investigated biochemical characteristics included: total soluble solids content (TSS), pH, titratable acidity, total phenolic content, vitamin C and antioxidant capacity (DPPH). The highest values of phenolic compounds, i.e. ellagic acid, rutin, quercetin, gallic acid, catechin, chlorogenic acid and caffeic acid, were as follows: 5.89, 133.60, 11.25, 40.90, 10.54, 97.59 and 21.93 g 100 g ⁻¹ , respectively. The highest values of total phenolics, vitamin C content and antioxidant capacity determined in the investigated mulberry genotypes were 2977.30 mg GAE g ⁻¹ , 31.34 mg 100 g ⁻¹ and 26.80%, respectively. The genotypes 64USA08, 64USA06 and 64USA10 can be recommended in terms of the most valuable chemical composition and used for future breeding purposes. It is desirable to take steps to implement an intensive programme for the preservation of Morus nigra L. biodiversity in Turkey.

Background: Drought is a major abiotic stress that restricts plant growth and efficiency although some nutrients such as silicon improve drought tolerance by regulating the biosynthesis and accumulating some osmolytes. In this regard, a completely randomized factorial design was performed with three factors including two genotypes (‘Maragheh’ and ‘Kashan’), three concentrations of silicon dioxide nanoparticles (SiO₂-NPs) (0, 50, and 100 mg L^− 1), and five concentrations of PEG (0, 25, 50, 75, and 100 g L^− 1) with three replications.Results: The findings showed that drought stress decreased protein content and it was improved by SiO₂-NPs, so the genotype of ‘Maragheh’ treated with 100 mg L^− 1SiO₂-NPs had the highest protein content. Under severe drought stress, had a higher membrane stability index (MSI) than ‘Kashan’, and the ‘Maragheh’ explants subjected to 100 mg L^− 1SiO₂-NPs exhibited the uppermost MSI. The explants supplemented with 100 mg L^− 1SiO₂-NPs sustained their photosynthetic parameters more in comparison with other treatments under drought stress conditions and as well as 100 mg L^− 1SiO₂-NPs showed higher content of protein and proline of ‘Maragheh’ than ‘Kashan’. Drought stress reducedFm,Fv/Fm, andFv, while SiO₂-NPs treatment enhanced these parameters. SiO₂-NPs also improved water deficit tolerance by enhancing the activity of antioxidant enzymes such as catalase (CAT), peroxidase (POD), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) and reducing lipid peroxidation and H₂O₂concentration.Conclusions: According to the findings, the genotype ‘Maragheh’ was more tolerance to drought stress than ‘Kashan’ by improving water balance, antioxidant enzyme activities, and membrane stability as it was obtained from the unpublished previous evaluation in in vivo conditions and we concluded based on these results, in vitro culture can be used for drought screening in Damask rose plants. The results of the current study revealed that the induced drought stress by polyethylene glycol (PEG) in two Damask rose genotypes was ameliorated with SiO₂-NPs and the tolerance genotypes were better than the sensitive ones in response to SiO₂-NPs treatment.

Melatonin acts as a seed germination activator, plant growth regulator, leaf senescence retardant, and, in general, has a multifunctional role as a ‘defence molecule’; furthermore, by interacting with other molecules, such as phytohormones and gaseous molecules, it greatly enhances plant adaptation to different environments. However, there are not enough studies about the use of melatonin on horticultural crops, and even fewer studies have outlined the differences related to this phytohormone use between protected environment and in open field. The two latter systems have different growing conditions that could lead to diversified application doses. As the choice of melatonin dose depends on all crop system components, the present research aimed to assess the effects of three melatonin concentrations (1 ppm, 5 ppm and 10 ppm) plus an untreated control, on yield, quality, and antioxidants of four strawberry cultivars (i.e., Kabarla, Fortuna, Sweet Ann, Festival) grown either in greenhouse or in open field. Research was conducted to assess the yield parameters were better affected by greenhouse than open field, and mean fruit weight was the highest in cultivar Sweet Ann. In open field 10 ppm showed the highest values of fruit number and yield, but in greenhouse did not differ from 5 ppm which led to the highest fruit number. At all melatonin doses, cultivar Kabarla demonstrated the highest yield, compared to the other cultivars, with the maximum value of about 46 t·ha⁻¹. Plant dry weight was 90% higher under greenhouse than in open field conditions, and 52% or 132% higher with cultivar Kabarla in comparison with Fortuna and Sweet Ann, respectively. The melatonin dose of 10 p.p.m showed 56% higher plant dry weight in comparison to the untreated control. Fortuna showed higher values of fruit dry matter, soluble solids, and glucose than Sweet Ann. The fruit dry matter was 7% lower at 10 ppm melatonin than in the untreated control. Fructose was higher under 1 ppm melatonin with 245 mg·g⁻¹ d.w. compared to the untreated control with 220 mg·g⁻¹ d.w. in Festival, whereas in Fortuna was the highest in the control fruits, the latter also showing the highest titratable acidity in Fortuna and Sweet Ann. The highest phenolics content was recorded under 10 ppm melatonin in open field, and with 5 ppm in greenhouse; the phenolics content was the highest under 1 ppm melatonin dose in Kabarla and 5 ppm in Fortuna. Under the protected environment 5 and 10 p.p.m. melatonin elicited the highest accumulation of ascorbic acid; 10 ppm were more effective in Fortuna and Sweet Ann, and 5 ppm in Festival. The most enhanced antioxidant activity was recorded under 5 p.p.m. melatonin dose in Fortuna and Festival. The present study confirms that the dose of melatonin to apply to strawberry crop closely relates both to cultivar and crop system.