Flowering Plants Research Articles

Tocotrienols in Eleven Species of Hypericum Genus Leaves

Saint John’s worts or goatweeds are mostly perennial flowering plants in the Hypericaceae family, formerly under the Clusiaceae family. Teas and macerations of the plants are common in traditional medicines and modern depression and cancer therapies. The most notable bioactive compounds in Hypericum are hyperforin and hypericin. While Hypericum contains a variety of carotenoid and phenolic compounds, which are well documented, there is little available information on tocopherols and almost none on tocotrienols. Considering the frequency of tocotrienol derivatives in Clusiaceae species, this study investigates and reports the presence of tocotrienols in eleven Hypericum species’ leaves: H. hircinum, H. hookerianum, H. calycinum, H. xylosteifolium, H. densifolium, H. prolificum, H. kalmianum, H. frondosum, H. olympicum, and two hybrids: H. × moserianum and H × ‘Rowallane’. Eight tocopherol and tocotrienol forms (α, β, γ, δ) were detected in the leaves, predominantly containing α-tocopherol. Tocotrienol content was most significant in Myriandra section species and was highest in H. prolificum (22.90 ± 0.63 mg 100 g−1), while the highest tocotrienol proportion was observed in H. × ‘Rowallane’ (54.12% of total tocochromanols) and H. prolificum (37.27% of total tocochromanols). The results demonstrated significant tocochromanol accumulation in Hypericum leaves.

Genetic Variability and Character Association Studies in Wheat (Triticum aestivum L. em. Thell) for Seed Yield and Its Contributing Traits

This study investigated genetic variability, correlation and path analysis in wheat 54 genotypes, including 40 F1 hybrids, 14 parental lines, and a standard check variety (HD-3086). The parental lines consisted of 10 females and 4 males, with the hybrids evaluated using a randomized block design (RBD) during the 2020-21 and 2021-22 rabi season. Analysis of Variance (ANOVA) revealed significant differences among genotypes for most traits, indicating considerable genetic variability. Genotypic correlation analysis identified strong positive relationships between grain yield per plant (GYPP) and key agronomic traits, such as spike length, spikelets per spike, grains per spike, grain yield per spike, harvest index, and test weight. Conversely, negative correlations with days to 50% flowering and plant height suggested that early flowering and shorter plants are beneficial for yield enhancement. Path coefficient analysis revealed that harvest index and biological yield had the most substantial positive direct effects on GYPP, while traits like protein content and days to maturity showed negative direct effects. Thus, using such traits like harvest index and biological yield in wheat improvement program could increase wheat yield”.

Birds and ants can favour the germination of an endemic Neotropical magnolia

ABSTRACT Background Seed dispersal, a fundamental process influencing the distribution and survival of most flowering plants, is key to the understanding of the ecology of tree species and forest restoration potential. However, little is known about the seed dispersal and germination of magnolias, especially in the Neotropics. Aims To elucidate the effect of the removal of the sarcotesta (red outer seed coat) of seeds by birds and ants on the germination of Magnolia vovidesii, a species endemic to Mexico. Methods We recorded birds consuming M. vovidesii seeds using motion-activated camera traps and focal observations for 36 days. In order to understand how birds and ants removed sarcotesta and how this was related to its germination, we made two independent experiments, one using three captive clay-coloured thrushes, and another one using ants in the field. Results We recorded nine species of birds that fed on magnolia seeds. The clay-coloured thrush, an important consumer of these seeds, eats and subsequently regurgitates, magnolia seeds without sarcotesta. We found that seeds whose sarcotesta had been removed by birds and ants had a significantly higher germination than those with sarcotesta (p < 0.0005). Conclusions Without the removal of the sarcotesta, magnolia seeds do not germinate at all. Our work demonstrates that birds and ants have a key role in preserving populations of magnolias.

Valeriana Officinalis: A Review of its Traditional Uses, Phytochemistry and Pharmacology

Valeriana officinalis, commonly known as Valerian, is a perennial flowering plant that has been used for centuries in traditional medicine for its sedative and anxiolytic properties. This comprehensive study aims to explore the botanical characteristics, geographical distribution, traditional uses, chemical constituents, pharmacological activities, health benefits, recommended dosages, and potential side effects of the Valerian plant. Through a detailed examination of both historical and contemporary research, this study provides an in-depth understanding of the therapeutic potential and applications of Valerian. The pharmacological efficacy of Valerian is primarily attributed to its rich chemical composition. Key constituents include volatile oils, valepotriates, and sesquiterpenes, with valerenic acid identified as a major active compound. These components are believed to work synergistically to enhance GABAergic neurotransmission, thereby exerting sedative and anxiolytic effects on the central nervous system. Contemporary pharmacological studies have confirmed Valerian’s ability to promote relaxation, improve sleep quality, and alleviate symptoms of anxiety.

COMPARARTIVE PHYTOREMEDIATING POTENTIALS OF Jatropha curcas, Ixora coceinea, Codiaeum variagatum, Andropogum tectorium, Panicum maximum, Zea mays, Cajanus cajan FOR Pb2+, Cd2+, Zn2+ AND Co2+

The emergence of the industrial revolution has led to an enormous increase in heavy metal pollution of the biosphere which subsequently became a threat to the environment and human life. Heavy metal pollution has been recognised as one of the most critical threats to soil and water resources, together with human health. The potential of Jatropha curcas, Ixora coceinea, Codiaeum variagatum(male and female), Andropogum tectorium, Panicum maximum, Zea mays and Cajanus cajan as suitable phytoremediators for soil matrix polluted with Zinc (Zn), Cobalt (Co), Cadmium (Cd) and Lead (Pb) at 0.1M and 0.5M concentrations, and at 8 and 12 weeks of inoculation is the aim of this work.The plants were grown in soils polluted with 0.1m and 0.5M solutions of Pb2+, Cd2+, Co2+ and Zn2+, harvested after 8 and 12 weeks of inoculation. They were washed, air-dried, ashed, digested and concentrations of the metal ions in the plants were analysed. The results showed that there were significant interaction effects between the plants and the concentration of metal ions in the absorption of Pb2+(P&lt; 0.01), Cd2+(P&lt; 0.01), Co2+ (P&lt; 0.01) and Zn2+ (P&lt; 0.001). There was also significant interaction effects plants and the time of harvest in absorption of Pb2+(P&lt; 0.01), Cd2+(P= 0.02) and Zn2+ (P&lt; 0.001). No significant interaction was observed for absorption of Co (P= 0.36). At 0.5M concentration of Pb2+ and Cd2+, the mean Pb2+ and Cd2+absorptions in Codiaeum variagatum (female) were significantly higher than those of other plants. Also Ixora coceinea had the highest mean absorption of Co2+ when inoculated with 0.5M of the metal ion and at 8 weeks. While the mean Zn2+ absorption in Codiaeum variagatum (male) was significantly than those of other plants when inoculated with 0.5M Zn2+ and at 12 weeks. The flowering plants- Codiaeum variagatum (male and female) and Ixora coceinea showed better absorption of the metal ions than all other plants. These potentials shown by the flowering plants indicated that the plants could serve both aesthetic and phytoremediating functions at the same time.

Investigation of Phytochemical Composition, Antioxidant and Antibacterial Activity of Five Red Flower Extracts

The presence of bioactive compounds in plants with red flowers constitutes a valuable natural resource for the food, pharmaceutical, and medical industries. This paper aims to highlight these characteristics to facilitate the selection of extracts according to market needs. The analyzed parameters can provide valuable insights into the compositional variability of the five red flower plants, as new sources of bioactive compounds and natural antioxidants of plant origin. Five plants with red flowers (Magnolia liliiflora, Chrysanthemum morifolium, Hibiscus sabdariffa, Petunia grandiflora, Rosa hybrida L.) were selected and investigated regarding their polyphenol concentration, total anthocyanins, antioxidant activity, phenolic compounds, and antimicrobial activity. Total polyphenols were found in concentrations ranging from 75.17 ± 0.16 mgGAE/g (C. morifolium) to 107.49 ± 0.19 mgGAE/g (R. hybrida L.), and total anthocyanins between 14.99 ± 0.13 mg Cy-3-Glu/g and 21.66 ± 0.18 mg Cy-3-Glu/g. The antioxidant activity DPPH/IC50 mg/mL for the extract from R. hybrida L. flowers reached a value of 29.35 ± 0.17 mg/g, with ABTS and FRAP achieving maximum values of 49.89 ± 0.24 mmol TE/g and 48.68 ± 0.23 mmol TE/g, respectively. The antibacterial activity was particularly evident against strains commonly encountered in human pathology, Escherichia coli and Staphylococcus aureus, with reduced or no impact on strains of Pseudomonas fluorescens and Proteus mirabilis. The results demonstrated that the extracts from the selected, red-flowered plants contain valuable biologically active compounds in generous quantities, thus recommending their use in the food, pharmaceutical, and medical sectors.

Effect of Geinstein on Regulation of Estrous Cycle in Albino Rats, Isolated from Flemingia vestita, an Ethnomedicinally Important Plant of Meghalaya, India

Flemingia vestita is a flowering plant belonging to the family of Fabaceae which is usually found in the Indian region including Khasi and Jaintia Hills of Meghalaya, India. It is cultivated for therapeutic use for its anti-microbial, anti-fungal, anti-helmintic, anticancer, anti-rheumatic, anti-inflammatory, antioxidant, and anti-histamine activities. The present study is to ascertain the phytochemical analysis of the root-tuber extract and modulating the effect of the Estrous Cycle in albino mice using Geinstein. The phytoestrogens present in the extract are iso-flavones and genistein which have a wide spectrum of biological activities including estrogenic effect. The number of leucocytes during the Meta-estrous at 0.1 ml/10 gm dose/body weight was maximum at ethanol extract while at 0.3 ml/10 gm dose/body weight was similar and maximum in both ethanol and methanol extract. Comparative cell number of interstitial connective tissues was maximum in ethanol followed by methanol and acetone extract. The present study concluded that the extract has a potential to modulate the estrogenic cycle in albino rats.

Cryo-EM structure of the NDH-PSI-LHCI supercomplex from Spinacia oleracea.

The nicotinamide adenine dinucleotide phosphate (NADPH) dehydrogenase (NDH) complex is crucial for photosynthetic cyclic electron flow and respiration, transferring electrons from ferredoxin to plastoquinone while transporting H+ across the chloroplast membrane. This process boosts adenosine triphosphate production, regardless of NADPH levels. In flowering plants, NDH forms a supercomplex with photosystem I, enhancing its stability under high light. We report the cryo-electron microscopy structure of the NDH supercomplex in Spinacia oleracea at a resolution of 3.0-3.3 Å. The supercomplex consists of 41 protein subunits, 154 chlorophylls and 38 carotenoids. Subunit interactions are reinforced by 46 distinct lipids. The structure of NDH resembles that of mitochondrial complex I closely, including the quinol-binding site and an extensive internal aqueous passage for proton translocation. A well-resolved catalytic plastoquinone (PQ) occupies the PQ channel. The pronounced structural similarity to complex I sheds light on electron transfer and proton translocation within the NDH supercomplex.

Michelia alba: A Review on Its Biological Profile and Ethnobotany in Java

Michelia alba DC (white champaca) is an ornamental, flowering, and aromatic plant that grows widely in tropical and subtropical areas of Southeast Asia. This plant has long been known as a medicinal plant in several regions in Southeast Asia. However, this plant is still not widely known by people in various parts of the world, the number of studies that examine this plant is still relatively small, and ethnobotanical discussions about this plant are difficult to find. This study aims to provide a review of the current ethnobotanical status of Michelia alba in Java, Indonesia, which includes its biological profile, role in Javanese customs, related myths, and scientific review in terms of its pharmacological activity. The results of the ethnobotanical study revealed that this plant is fairly unique because it is often associated with magical things and is very closely related to various cultural practices of the Javanese indigenous people (kejawen). Scientifically, the results of research prove that the M. alba plant does contain various chemical constituents that have many benefits. The pharmacological activities of M. alba reported include anti-cancer, antistress, anti-fungal, antioxidant, skin protection, and effective in killing Trypanosoma parasites.

Floral Resource Integration: Enhancing Biocontrol of Tuta absoluta Within Sustainable IPM Frameworks

The tomato leaf miner, Tuta absoluta, is a pest threatening global tomato production. This pest’s adaptability and resistance to chemical insecticides have necessitated integrated pest management (IPM) strategies prioritizing sustainable alternatives. This review explores the role of biological control agents (BCAs) in managing T. absoluta populations, emphasizing the integration of floral resources to enhance their efficacy. Predatory mirids such as Macrolophus pygmaeus and Nesidiocoris tenuis and parasitoids such as N. artynes and Trichogramma spp. are pivotal in pest suppression; however, their performance depends on nutritional and habitat support. Floral resources provide essential sugars and proteins, improving the longevity, fecundity, and predation efficiency of these BCAs. This review synthesizes case studies highlighting the benefits of selected flowering plants, such as Lobularia maritima and Fagopyrum esculentum, in supporting predator and parasitoid populations while minimizing advantages to T. absoluta. Mechanisms such as nectar quality, floral accessibility, and spatial–temporal resource availability are explored in detail. Additionally, the challenges of selective floral attraction, microbial impacts on nectar composition, and the unintended support of non-target organisms are discussed. This review proposes targeted floral management strategies to optimize BCA performance within IPM systems by integrating ecological and chemical insights. This approach offers a pathway toward reducing chemical pesticide reliance, fostering sustainable agriculture, and mitigating the economic impacts of T. absoluta infestations.

Evolution of interorganismal strigolactone biosynthesis in seed plants.

Strigolactones (SLs) are methylbutenolide molecules derived from β-carotene through an intermediate carlactonoic acid (CLA). Canonical SLs act as signals to microbes and plants, whereas noncanonical SLs are primarily plant hormones. The cytochrome P450 CYP722C catalyzes a critical step, converting CLA to canonical SLs in most angiosperms. Using synthetic biology, we investigated the function of CYP722A, an evolutionary predecessor of CYP722C. CYP722A converts CLA into 16-hydroxy-CLA (16-OH-CLA), a noncanonical SL detected exclusively in the shoots of various flowering plants. 16-OH-CLA application restores control of shoot branching to SL-deficient mutants in Arabidopsis thaliana and is perceived by the SL signaling pathway. We hypothesize that biosynthesis of 16-OH-CLA by CYP722A was a metabolic stepping stone in the evolution of canonical SLs that mediate rhizospheric signaling in many flowering plants.

Floral Regulation: The Significant Virtue of Horticultural Flowering Plants

Flowering is a complex developmental mechanism and is essential for successful reproduction in plants. Complex regulatory networks transform vegetative shoot apical meristems into inflorescence meristems. Further, floral meristems transition to floral bud outgrowth and flowering. Floral regulatory pathways are independently involved in flowering, and most of what we know about genetic regulation comes from model plants. Despite the advancements in plant development biology, the understanding of molecular mechanisms and floral signals in horticultural plants is complex. Studies on gene regulatory mechanisms provide a global view of flowering in horticultural plants. In this paper, we discuss the flowering pathways converging on complex gene regulatory mechanisms and summarize the recent findings in horticultural plants in order to help us understand how they regulate flowering and provide an update for future research.

A Survey of Wild Indigenous Cryptostylis ovata Orchid Populations in Western Australia Reveals Spillover of Exotic Viruses.

Cryptostylis ovata is a terrestrial orchid endemic to southwestern Australia. The virus status of C. ovata has not been studied. Eighty-three C. ovata samples from 16 populations were collected, and sequencing was used to identify RNA viruses from them. In one population, all tested plants were co-infected with isolates of the exotic-to-Australia viruses Ornithogalum mosaic virus (OrMV) and bean yellow mosaic virus (BYMV). In another population, one plant was infected with BYMV. No viruses were detected in the remaining populations. The OrMV isolate shared 98-99% nucleotide identity with isolates identified from wild indigenous Lachenalia (Iridaceae) plants in South Africa. This suggests that the source of OrMV in C. ovata may be one or more bulbous iridaceous flowering plants of southern African origin that were introduced to Western Australia as ornamentals and that have since become invasive weeds. One BYMV isolate from C. ovata also exhibited 99% nucleotide identity with strains isolated from the exotic leguminous crop Lupinus angustifolius in Western Australia, suggesting possible spillover to indigenous species from this source. This study with C. ovata highlights the probable role of invasive weeds and exotic crops as sources of exotic virus spillovers to indigenous plants.

Complete Chloroplast Genomes of 9 Impatiens Species: Genome Structure, Comparative Analysis, and Phylogenetic Relationships.

Impatiens is a genus of functional herbaceous plants in the Balsaminaceae, which are not only of great ornamental value and one of the world's top three flower bedding plants but also have a wide range of medicinal and edible uses. Currently, the taxonomy and phylogenetic relationships of Impatiens species are still controversial. In order to better understand their chloroplast properties and phylogenetic evolution, nine Impatiens plants (Impatiens repens, Impatiens rectirostrata, Impatiens baishaensis, Impatiens rostellata, Impatiens faberi, Impatiens oxyanthera, Impatiens tienchuanensis, Impatiens blepharosepala, Impatiens distracta) were sequenced, and their complete chloroplast genomes were analysed. Nine species of Impatiens chloroplast genomes ranged in length from 150,810 bp (I. rectirostrata) to 152,345 bp (I. blepharosepala). The chloroplast genomes were all typical circular DNA molecules, and the GC content in each region was consistent with the published chloroplast genomes of Impatiens plants. The results showed that the seven mutational hotspots (trnL-UAG, ndhG, ycf1, ccsA, rrn23, trnA-UGC, and ycf2) could be used as supporting data for further analyses of the phylogenetic tree and species identification. In addition, the results of the phylogenetic tree support that Balsaminaceae is a monophyletic taxon, and that Hydrocera triflora is at the base of the branch, is the original species of Balsaminaceae, and is in a sister group relationship with Impatiens species. The results of this paper enrich the data of Impatiens chloroplast genomes, and the availability of these chloroplast genomes will provide rich genetic information for species identification, thus enhancing the taxonomic accuracy and phylogenetic resolution of Impatiens, and further promoting the investigation and rational use of Impatiens plant resources.

Temporal variation in floral scent emission of a woody plant and flower visiting behaviour of male and female flies

Most flowering plants rely on insects for pollination and flowers are advertised using odor and visual cues. Flower scent consists of a complex blend of volatile compounds of which the emission can vary over time (and space) within species. Pollinator foraging behaviour, such as the choice for flowers and the time spent gathering nectar and/or pollen, can also show significant intraspecific variation. Underlying variation in pollinator behaviour can be sensory or foraging‐related biases among sexes or individuals. Investigating the role of temporal variation in floral volatiles on visitation behaviour of male and female pollinators is largely unexplored. We examined temporal variation in the emission of scent of yellowhorn Xanthoceras sorbifolium flowers, visitation behaviour of its main pollinators, male and female Bibio rufiventris flies, and their responses to floral volatile compounds using field experiments and controlled bioassays. Our results show significant daily fluctuations in floral volatile emission of X. sorbifolium in the field. The relative emission of 1‐octen‐3‐ol, 1‐octanol, benzaldehyde, and α‐farnesene increased from 9:00 to 15:00 h, while (Z)‐3‐hexen‐1‐ol, (E)‐2‐hexen‐1‐ol, (E)‐2‐hexenal, 2‐methyl‐6‐hepten‐1‐ol, (E)‐2‐nonenal, 2,6,6‐trimethyl‐2‐cyclohexene‐1‐methanol, (E)‐2‐nonenal and (E,Z)‐2,6‐nonadienal decreased. In concert, we observed an increase in visits and visitation duration for male pollinators, but a decrease for female visitation duration. Pollinators exhibited sex‐specific responses to floral volatiles, with attraction to 1‐octen‐3‐ol and 1‐octanol for B. rufiventris males, while (E)‐2‐nonenal, (E,Z)‐2,6‐nonadienal and (E)‐2‐hexenal attracted females. Our study shows that temporal variation in floral scent may explain differences in flower visitation by male and female pollinators through sex‐specific responses to floral volatiles. Investigating sex‐based differences exhibited by pollinators and temporal variation in floral scent emission will help understand the dynamic nature of plant–pollinator interactions.

An Overview of the Current Scientific Evidence on the Biological Properties of Abelmoschus esculentus (L.) Moench (Okra).

Abelmoschus esculentus (L.) Moench, commonly known as okra or lady's finger, is an annual flowering plant belonging to the Malvaceae family. Okra is a native plant in Africa as well as a traditional medicine in Africa and India for treating different diseases and conditions. Today, okra is widely consumed as a vegetable and is increasingly recognized as a superfood due to its rich nutritional profile and potential pharmacological benefits. Research indicates that okra exhibits a range of biological activities, including antidiabetic, antihyperlipidemic, antifatigue, vasoprotective, hepatoprotective, antitumor, anti-inflammatory, and antimicrobial effects. Despite its promising therapeutic potential, research on the active compounds in okra and evaluating efficacy in clinical settings remains limited. This review aims to consolidate existing scientific knowledge on the biological and pharmacological properties of okra, thereby encouraging further investigation into its health benefits. Ultimately, this could pave the way for the development of functional foods or health supplements that leverage okra as a key ingredient to prevent chronic diseases and enhance overall health outcomes.

Natural Enemies Acquire More Prey Aphids from Hormone-Treated Insect-Attracting Plants.

Exogenous plant hormones regulate the agronomic and physiological performance of plants and thus can influence the abundance of insect groups. We surveyed the arthropods on flowering plants Cnidium monnieri and found that the abundance of natural enemies Propylaea japonica and Orius minutus in the plots treated with salicylic acid (SA) and indole acetic acid (IAA) was significantly increased compared with those in the clean water (control) plots. Then, we investigated the effects of spraying SA, IAA, and clean water on the population parameters of Semiaphis heraclei reared on C. monnieri. Our results from the age-stage, two-sex life table analysis revealed a significantly shorter pre-adult duration for aphids reared on SA-treated C. monnieri compared to those reared on the other two treatments. The intrinsic rate of increase, finite rate of increase, and net reproductive rate of aphids reared on SA- and IAA-treated C. monnieri were significantly higher than those of aphids reared on clean water-treated C. monnieri. The fecundity rate was higher under the SA and IAA treatments than in the control, but the difference was not significant. This improved the ability of flowering plants to attract natural enemies by providing a larger food source.

Bioactive Compounds from Vegetal Organs of Taraxacum Species (Dandelion) with Biomedical Applications: A Review.

Taraxacum officinale (dandelion) is a perennial flowering plant of the Asteraceae family that has spread globally and is well-known for its traditional uses. The aim of this work is to provide a detailed review of scientific literature on the genus Taraxacum from the last two decades, with particular emphasis on the biological and pharmacological characteristics of dandelions. The traditional use of Taraxacum species and their potential use in medicine are assessed. In addition, individual papers describing principal pathways and molecules modulated by Taraxacum in antitumoral, anti-inflammatory, antidiabetic, hepatoprotective, immunomodulatory, antimicrobial, and antioxidant activities are presented. This review of phytochemical studies reveals that dandelions contain a wide range of bioactive compounds, such as polyphenols, phytosterols, flavonoids, carotenoids, terpene, and coumarins, whose biological activities are actively explored in various areas of human health, some constituents having synergistic activities, including antioxidant, antimicrobial, anti-inflammatory and anticancer activities. The study provides a screening of Taraxacum sp. chemical composition, an assessment of the main pharmacological properties, and a description of relevant studies supporting the use of dandelion for its particularly valuable and diversified therapeutic potential in different diseases.

Turnover and change in the street flora of Cambridge, UK

ABSTRACT Background The general characteristics of urban floras are well studied, but less information is available on the behaviour of species at the street scale. Aims To discuss the phenology and dynamics of the street flora. Methods Vascular plants in flower were recorded at monthly intervals from January 2016 in eight connected streets in a primarily residential area of urban Cambridge, which is neither markedly deprived nor especially affluent. Results There is a regular seasonal cycle with fewest flowering species in February or March and most in June or July. Monthly totals in winter are correlated with the mean minimum temperature of the preceding month, and occasional severe summer droughts reduce the number of species flowering in August. In 2023 and 2024 the cessation of herbicide use by the city council, combined with wet summer weather, led to record numbers of flowering species. Species flowering in all years and recorded in all streets, the basic street flora, contrast with persistent colonies of rare species and a large number of casual occurrences. Conclusions The street flora has a core of species which may change over the decades, joined by an ever-fluctuating cast of transient species.

Diurnal rhythm of carotenoid metabolism in the intertidal red algal seaweed Neoporphyra haitanensis

Biological rhythms governing metabolic and developmental processes are widespread in organisms, ranging from prokaryotic cyanobacteria to mammals and flower plants. Species of the genus Porphyra sensu lato (e.g., Porphyra, Pyropia, Neoporphyra, etc.) are major red algal seaweeds important to the marine fisheries industry in northeast Asia. Over a long evolutionary history, these seaweeds have adapted to the intertidal zone environment, which is characterized by periodic extreme stresses such as high light, high temperature, high salinity, and drought. However, very little is known about the rhythmic regulation of these seaweeds in response to the shifting environment. In this study, we entrained N. haitanensis thalli with a 12 h/12 h light/dark regime under constant temperature and light intensity, and analyzed the contents of carotenoid constituents and the transcript abundances of genes involved in carotenoid metabolism. Our results clearly demonstrated a 1.52 (zeaxanthin)–2.13 (β-carotene)-fold change between the highest and lowest amounts of carotenoids, and a 7.66 (NhCHYB)–224.00 (NhZISO)-fold change in the expression levels of genes, over the course of a day. These variations indicate that the fluctuations at both metabolic and transcriptional levels of carotenoid metabolism during the light/dark shifting are significant and cannot be neglected, highlighting the need to use a series of parallel non-treated controls instead of a pre-treatment control to avoid the potential confounding effects of the treatment and the diurnal rhythm.