Foliar calcium effects on quality and primary and secondary metabolites of white-fleshed ‘Lemonato’ peaches

‘Lemonato’ is a Greek peach melting-flesh white-flesh cultivar with high nutritional value highly appreciated by the consumers. This study aimed to evaluate the effect of pre-harvest foliar calcium application on fruit quality, primary metabolite profile, antioxidant activity, total phenolic content, and phenolic profile of the ‘Lemonato’ peach, clone ‘Stamatis’. The experiment was conducted for two years, 2019 and 2020, in two commercial orchards at Kato Lehonia and Agios Vlasios regions, central Greece, where the ‘Lemonato’ clone ‘Stamatis’ is traditionally cultivated. The treatments were organic calcium (Ca), calcium–silicate in nanoparticles (Ca–Si), and calcium chloride (CaCl2). Foliar application of the different Ca formulations, commonly used as a horticultural practice, were not effective at improving the fruit quality characteristics in this clone, which is characterized by fruit softening during ripening. The study revealed the sugars and organic acid composition and phenolic profile of the ‘Lemonato’ peach, clone ‘Stamatis’. Peach fruit quality, primary metabolites, and phenolic compounds of the two orchards showed a different response to organic Ca and Ca–Si, indicating that genetic or environmental factors may also be involved. A higher concentration of organic Ca and CaCl2 increased the peach fruit phenolic compounds content and the total antioxidant activity, improving the fruit nutritional qualit

Yield and silymarin content in milk thistle (Silybum marianum (L.) Gaertn.) fruits affected by the nitrogen fertilizers

Milk thistle (Silybum marianum (L.) Gaertn.) is a common weed that has been introduced as a medicinal plant for silymarin production. This renders it important to optimize cultivation techniques, including fertilization. In the present study, a two-year field experiment was conducted to evaluate the influence of conventional and stabilized nitrogen fertilizers on plant growth, fruit yield, and fruit quality. The experiment was conducted in a randomized complete block design with five fertilization treatments (control, conventional nitrogen fertilizer applied at 75 kg/ha and 125 kg/ha, and stabilized nitrogen fertilizer applied at 75 kg/ha and 125 kg/ha. Nitrogen fertilization had a significant effect on vegetative and yield parameters. Specifically, the application of nitrogen fertilizers positively influenced rosette diameter, height, aboveground dry biomass, total chlorophyll content, number of capitula per plant, number of fruits per central capitulum, and fruit yield. In particular, in most traits, the usage of high nitrogen levels of the two types of fertilizer had the most pronounced impact. The application of the stabilized fertilizer at a rate of 125 kg N/ha induced an increase in fruit yield of up to 29.6 %. Nitrogen fertilization had no impact on the accumulation of oil and silymarin in the fruits, although some effects on oil and silymarin yield were noted. In general, the application of nitrogen fertilizers had no effect on the antioxidant activity or total phenolic content of the fruit extracts. Finally, climatic conditions affected the growth and productivity of milk thistle, as fruit yield was favoured by wet conditions. © 2021 Elsevier B.V

Effects of Two Varieties and Fertilization Regimes on Growth, Fruit, and Silymarin Yield of Milk Thistle Crop

Milk thistle is an alternative crop to winter cereals for southern Europe as this species is drought tolerant and its fruits contain silymarin. The aim of this study was to assess the impact of two varieties and fertilization regimes (sheep manure and inorganic fertilizer) on crop productivity. A two-factor experiment was conducted in a randomized split-plot design with three replicates. The varieties were Palaionterveno and Spata, while the fertilization treatments were control, sheep manure, and calcium ammonium nitrate applied at 75 and 125 kg N ha−1 . Variety and fertilization significantly affected plants development and productivity, as well as oil and silymarin yield. The use of manure and inorganic nitrogen fertilizer increased rosette diameter, oil and silymarin yield, aboveground biomass, and fruit yield. The influence of inorganic fertilization, regardless of the application dose, was more apparent than organic fertilization. Moreover, variety significantly affected plants growth and silymarin content, as well as silymarin composition. The variety Spata had the greatest silymarin content, reaching 4.40%, and a high silybin B concentration. In conclusion, the selection of a suitable variety is important for achieving high fruit and silymarin yields, while inorganic nitrogen fertilization can maximize the productivity of the milk thistle crop. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Cultivation practices, adaptability and phytochemical composition of jerusalem artichoke (Helianthus tuberosus l.): A weed with economic value

The Jerusalem artichoke (Helianthus tuberosus L.) is a perennial weed that is cultivated for bioethanol production or pharmaceutical purposes, as its aerial parts and tubers contain several chemical compounds. This review summarizes important data on the effects of the main cultivation practices (e.g., the planting density and pattern, weed management, fertilization, irrigation, genotypes and harvest) on tuber yield and quality. The most widespread method for the propagation of the Jerusalem artichoke is planting the tubers directly in the field, with a plant density of about 33,000– 47,000 plants ha−1 . Weed management is based on herbicide application, mechanical cultivation and hand hoeing, while the nutrient requirements are low, and irrigation relies on weather conditions. For instance, under Mediterranean semi-arid conditions, the crops are irrigated from June to September. In addition, the harvest time depends on the genotype and the purpose of cultivation, which is an important consideration for obtaining a high-quality product. In conclusion, Jerusalem artichoke yield and quality depend on several factors, and this plant, due to its high productivity, constitutes a promising crop with numerous uses. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Weed interference with peppermint (Mentha x piperita L.) and spearmint (Mentha spicata L.) crops under different herbicide treatments: effects on biomass and essential oil yield

BACKGROUND: ‘Minor crops’ such as spearmint and peppermint are high added value crops, despite the fact that their production area is comparably small worldwide. The main limiting factor in mint commercial cultivation is weed competition. Thus, field experiments were carried out to evaluate the effects of weed interference on growth, biomass and essential oil yield in peppermint and spearmint under different herbicide treatments. RESULTS: The application of pendimethalin and oxyfluorfen provided better control of annual weeds resulting in higher crop yield. Additionally, when treated with herbicides both crops were more competitive against annual weeds in the second year than in the first year. All pre-emergence herbicides increased biomass yield, since pendimethalin, linuron and oxyfluorfen reduced the density of annual weeds by 71–92%, 63–74% and 86–95%, respectively. Weed interference and herbicide application had no effect on essential oil content; however, a relatively strong impact on essential oil production per cultivated area unit was observed, mainly due to the adverse effect of weed interference on plant growth. CONCLUSION: Considering that pendimethalin and oxyfluorfen were effective against annual weeds in both spearmint and peppermint crops, these herbicides should be included in integrated weed management systems for better weed management in mint crops. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industr

Effects of Post-Emergence Herbicides and Period of Johnsongrass (Sorghum halepense (L.) Pers.) Control on Growth and Yield of Sunflower Crops

Sunflower is an important industrial crop since it is grown all over the world for oil production, while Johnsongrass (Sorghum halepense (L.) Pers.) is characterized by great competitiveness and can severely impair plant growth and crop productivity. Thus, a two-year field experiment was conducted to evaluate the impact of Johnsongrass control practices on plant growth, seed yield, and oil content of sunflower crop. The results indicated that Johnsongrass competition negatively affected sunflower growth and productivity as the lowest values of height, dry biomass, seed, and oil yields were recorded at the weed-infested treatment, followed by the weed infested for 30 days after sowing. All the other treatments had a positive effect on vegetative and yield parameters. Moreover, fluazifop-p-butyl, quizalofop-p-ethyl, and the combination of fluazifop-p-butyl and imazamox effectively controlled Johnsongrass. Specifically, in 2020, the lowest dry weight of Johnsongrass was observed in the plots where fluazifop-p-butyl + imazamox were applied. Thus, the results of this study clearly showed that the use of the above-mentioned herbicides can improve the seed and oil yield of a sunflower crop by managing Johnsongrass, while the competition of this rapidly growing weed for a short period of 30 days can significantly reduce crop yield. © 2022 by the authors. Licensee MDPI, Basel, Switzerland