Search

Plant secondary metabolites (SMs) play a crucial role in shielding plants from pathogens and environmental stressors. These natural products find widespread applications across various industries, including pharmaceutical, food, cosmetic, and healthcare. However, the quantity and quality of these compounds in plants can be influenced by factors such as genetics, morphology, plant age, and the seasonal and daily variations. The timing of harvest holds particular significance for medicinal and aromatic plants (MAPs) as their active compounds peak at a specific moment during the plant growth cycle. Determining the optimal harvest time is essential to ensure the plants meet their intended cultivation goal. In this review, we analyzed how developmental and external factors impact the qualitative and quantitative effectiveness of SMs in MAPs. We examined recent studies on the effects of environmental and developmental factors on SMs of MAPs, compiling relevant data for analysis. The results of this review demonstrate how these factors influence the quantity and quality of plant SMs, underscoring the importance of determining the optimal harvest time (known as the balsamic time) to maximize the utilization of these compounds. Our findings offer crucial insights into the factors affecting SMs, serving as a tool for quality control in MAPs production. Moreover, this review can be a valuable resource for researchers, farmers, and industrial users aiming to optimize plant growth and harvest timing for maximum yield. Overall, our review provides valuable information for devising effective strategies to produce high-quality MAPs products. [Display omitted] • Morpho-phenological stages and timing significantly influence plant secondary metabolites (SMs). • Optimal harvest timing is crucial for achieving desired outcomes, as SMs peak at specific stages of the plant's growth cycle.. • The modification of SMs may occur due to changes the expression of biosynthesis genes. • The review proposes the concept of the "balsamic time" for optimal harvesting of various SMs in medicinal and aromatic plants. [ABSTRACT FROM AUTHOR]

Abstract: Origanum vulgare subsp. hirtum (Link) Ietswaart (Greek oregano) has been cultivated since ancient times thanks to its herbal and therapeutic properties. Currently, it is added in various commercial preparations thanks to its essential oil composition. This group of secondary compounds is affected in quantity and quality by biotic and abiotic factors during the cultivating phase and by the postharvest management. Thus, the aims of the work were to study: (1) how the growing conditions (soil full-light treatment; pot full-light treatment; pot 50%-shade treatment) can affect the essential oil content and the essential oil profile of Greek oregano branches at full-blossoming stage; and (2) how the postharvest management (distillation of the essential oil from fresh herbs, dehumidified herbs or oven-dried herbs) can affect the essential oil content and the essential oil profile of this species. The growing conditions significantly affected the biometrical parameters. The pot full-light treatment contained the highest dry matter percentage (36.5%) and the highest essential oil content, which was directly correlated to the former parameter (r =0.890**). The postharvest management did not affect the essential oil content. The growing condition significantly affected the characterizing γ-terpinene, cis-sabinene hydrate, 4-terpineol, α-terpinene, linalyl acetate, and β-bisabolene, while it did not affect carvacrol (mean value 15.8%), p-cymene (mean value 6.0%), or sabinene (mean value 3.9%). The postharvest management significantly affected carvacrol, cis-sabinene hydrate, 4-terpineol, p-cymene, α-terpinene, linalyl acetate, and β-bisabolene, while it did not affect γ-terpinene (mean value 14.7%). The response of some compounds to growing conditions led us to hypothesise an essential oil profile of the plants grown in pots at 50%-shade to be more of a vegetative stage type oil than the essential oil profile of the plants grown in soil, although all were at the blossoming stage. The analyses on the individual compounds indicated that, even though the essential oil content in oregano did not change with a change in postharvest management, biochemical changes occurred on the profile. These could be due to enzyme activity, dilution effect or temperature effect during the drying processes. The oven-drying process and the dehumidifying process changed the essential oil profile in a similar way compared to the essential oil profile distilled from fresh herbs. Thus, when it is not possible to extract the essential oil directly from fresh herbs, processors can dry the oregano according to the equipments they have available. [Copyright &y& Elsevier]

A. vera is one of the most economically important medicinal plants in many countries which is widely used in food, cosmetics and pharmaceutical industries. Water stress is the primary environmental factor that limits crop production. Therefore, in order to study the effects of water stress (20, 40, 60 and 80%) of the field capacity (FC) and zeolite (0, 4 and 8 g kg −1 soil) on growth, yield and chemical compositions of A. vera an experiment was conducted in 2013 and 2014. The plants were harvested 90, 180 and 270 days after imposing the treatments. The greatest number of new leaves and pup were produced by the plants irrigated 20 and 40% FC with 8 g zeolite, respectively. Generally, the highest leaf fresh weight and gel fresh weight were observed 270 days after imposing the treatments when plants were irrigated after depleting 40% of the FC and treated with 8 g zeolite. Water use efficiency of A. vera increased with less water and more zeolite availability. In addition, the results indicated that the maximum aloin and proline accumulation were obtained 90 days after imposing the treatments when the plants were irrigated after depleting 80% and 60% of the FC where no zeolite was applied, respectively. Irrigation after 80% depletion of the FC without zeolite application resulted in highest fructose and glucose content. In general, zeolite application could alleviate water stress adverse effects, and improved plant growth and yield. Severe water stress decreased leaf yield and plant growth while caused an increase in phytochemical and biochemical compounds. [ABSTRACT FROM AUTHOR]

Aloe vera L. is one of the most important medicinal plants in the world. In order to determine the effects of light intensity and water deficit stress on chlorophyll (Chl) fluorescence and pigments of A. vera , a split-plot in time experiment was laid out in a randomized complete block design with four replications in a research greenhouse. The factorial combination of three light intensities (50, 75 and 100% of sunlight) and four irrigation regimes (irrigation after depleting 20, 40, 60 and 80% of soil water content) were considered as main factors. Sampling time was considered as sub factor. The first, second and third samplings were performed 90, 180 and 270 days after imposing the treatments, respectively. The results demonstrated that the highest light intensity and the severe water stress decreased maximum fluorescence (F m ), variable fluorescence (F v )/F m , quantum yield of PSII photochemistry (Ф PSII ), Chl and photochemical quenching (qP) but increased non-photochemical quenching (NPQ), minimum fluorescence (F 0 ) and Anthocyanin (Anth). Additionally, the highest F m , F v /F m , Ф PSII and qP and the lowest NPQ and F 0 were observed when 50% of sunlight was blocked and irrigation was done after 40% soil water depletion. Irradiance of full sunlight and water deficit stress let to the photoinhibition of photosynthesis, as indicated by a reduced quantum yield of PSII, Ф PSII , and qP, as well as higher NPQ. Thus, chlorophyll florescence measurements provide valuable physiological data. Close to half of total solar radiation and irrigation after depleting 40% of soil water content were selected as the most efficient treatments. [ABSTRACT FROM AUTHOR]

Salvia officinalis is commonly used as an ingredient in the food industry and has been shown to possess several biological activities. The essential oil (EO) of S. officinalis is characterized by thujones compounds, which are subjected to certain limits in the European Union (EU), as food additive. Sage inflorescences have different profile compared to leaves, with lower content in thujones, and could be exploited in the food sector. The yield of S. officinalis inflorescence can be affected by various cultural techniques, while postharvest management of the raw material could affect the EO quality, depending on whether it is extracted from fresh or dried inflorescences. In this regard, studying the factors which have a role in the EO quality and quantity is necessary. A 2-year study has been conducted to compare inflorescences and oil yield of three sage selections (S. officinalis ; S. officinalis subsp. lavandulifolia ; and S. officinalis 'Extrakta'), at two plant densities (4.76 plants/m2; 2.86 plants/m2), and two weed control techniques (manual vs. mulching). After harvest, the additional effect of two postharvest management systems (EO from fresh herbs; EO from 50 °C oven-dried herbs) on the EO quality was assessed too. All the tested selections synthesised low thujone contents in the inflorescences. The study showed that the plants age can influence the EO profile, while genetic can interact with some cultural techniques, leading to an increase in the EO content, and to the EO profile modification. The drying process changed the EO composition according to the drying temperatures. In specific, the oven-drying temperature of 50 °C reduced the EO content by 75%, according to the used chemical compound. Furthermore, the results showed that 50 °C, the most commercial temperature used for drying herbs, is less suitable to preserve the terpene fraction of the EO of sage inflorescences, suggesting that either lower temperatures or other drying methods should be recommended. [Display omitted] • The genetic can interact with some cultural techniques, modifying the EO. • Sage inflorescences have lower thujone contents than leaves. • Plants age can modify the EO profile. • The drying process has shown to be a relevant factor that affects the EO. [ABSTRACT FROM AUTHOR]

• Optimal LED light intensity for lettuce and basil indoor growing is addressed; • Maximum yield and leaf area is achieved at 250 μmol m-2 s-1; • 250 μmol m-2 s-1 increased chlorophyll and improved stomatal functions in leaves; • In lettuce, PPFD ≥ 200 μmol m-2 s-1 raised antioxidant capacity, phenolics and flavonoids; • Water, energy and light use efficiencies were optimized at 250 μmol m-2 s-1; Indoor plant cultivation systems are gaining increasing popularity because of their ability to meet the needs of producing food in unfavourable climatic contexts and in urban environments, allowing high yield, high quality, and great efficiency in the use of resources such as water and nutrients. While light is one of the most important environmental factors affecting plant development and morphology, electricity costs can limit the widespread adoption of indoor plant cultivation systems at a commercial scale. LED lighting technologies for plant cultivation are also rapidly evolving, and lamps for indoor cultivation are often designed to optimize their light emissions in the photosynthetically active spectrum (i.e. red and blue), in order to reduce energetic requirements for satisfactory yield. Under these light regimens, however, little information is available in literature about minimum photosynthetic photon flux density (PPFD) for indoor production of leafy vegetables and herbs, while existing literature often adopts light intensities from 100 to 300 μmol m-2 s-1. This study aims at defining the optimal PPFD for indoor cultivation of basil (Ocimum basilicum L.) and lettuce (Lactuca sativa L.), by linking resource use efficiency to physiological responses and biomass production under different light intensities. Basil and lettuce plants were cultivated at 24 °C and 450 μmol mol-1 CO 2 under red and blue light (with red:blue ratio of 3) and a photoperiod of 16 h d-1 of light in growth chambers using five PPFD (100, 150, 200, 250 and 300 μmol m-2 s-1, resulting in daily light integrals, DLI, of 5.8, 8.6, 11.5, 14.4 and 17.3 mol m-2 d-1, respectively). A progressive increase of biomass production for both lettuce and basil up to a PPFD of 250 μmol m-2 s-1 was observed, whereas no further yield increases were associated with higher PPFD (300 μmol m-2 s-1). Despite the highest stomatal conductance associated to a PPFD of 250 μmol m-2 s-1 in lettuce and to a PPFD ≥ 200 μmol m-2 s-1 in basil, water use efficiency was maximized under a PPFD ≥ 200 μmol m-2 s-1 in lettuce and PPFD ≥ 250 μmol m-2 s-1 in basil. Energy and light use efficiencies were increased under a PPFD of 200 and 250 μmol m-2 s-1 in lettuce and under a PPFD of 250 μmol m-2 s-1 in basil. Furthermore, in lettuce grown under 250 μmol m-2 s-1 antioxidant capacity, phenolics and flavonoids were higher as compared with plants supplied with PPFD ≤ 150 μmol m-2 s-1. Accordingly, a PPFD of 250 μmol m-2 s-1 seems suitable for optimizing yield and resource use efficiency in red and blue LED lighting for indoor cultivation of lettuce and basil under the prevailing conditions of the used indoor farming set-up. [ABSTRACT FROM AUTHOR]