Effect of Shading on Development, Yield and Quality of Bastard Balm Herb (Melittis melissophyllum L.).

The aim of the study was to assess the effects of Melittis melissophyllum shading on its development and accumulation of phenolics. Their content (verbascoside, apiin, luteolin-7-O-glucoside, coumarin, 3,4-dihydroxycoumarin, o-coumaric acid 2-O-glucoside as well as o-coumaric, p-coumaric, chlorogenic, caffeic, ferulic and cichoric acid) was determined in the herb using HPLC-DAD. The results showed that the content of abovementioned flavonoids and phenolic acids was highest in plants grown under full sunlight. On the other hand, a higher content of coumarin was observed in shaded plants, especially after the seed-setting stage. A similar tendency was noted for the amount of chlorophyll a and b. The content of hydrogen peroxide and malondialdehyde, the activity of polyphenol oxidase and catalase and the antioxidant capacity of plant extracts (measured using DPPH, ABTS and FRAP assays) were found to be the highest in the plants grown in full sunlight. However, the plants grown in moderate (30%) shade were found to thrive best.

Effects of Composite LED Light on Root Growth and Antioxidant Capacity of Cunninghamia lanceolata Tissue Culture Seedlings.

We used the 12th generation of the Cunninghamia (C.) lanceolata tissue culture seedlings, and white light emitting diode (LED) light as control (CK). We applied five composite LED light treatments, red-blue 4:1, 8:1 (4R1B and 8R1B), red-blue-purple 8:1:1 (8R1B1P), and red-blue-purple-green 6:1:1:1, 8:1:1:1 (6R1B1P1G and 8R1B1P1G), to study the effects of light quality on root growth characteristics and antioxidant capacity of C. lanceolata tissue culture seedlings. The results showed that: (1) rooting rate, average root number, root length, root surface area, and root activity were higher with 6R1B1P1G and 8R1B1P1G treatments compared to 4R1B, 8R1B, 8R1B1P and CK treatments; and the root growth parameters under the 8R1B1P1G treatment were as high as 95.50% for rooting rate, 4.63 per plant of the average number of root, 5.95 cm root length, 1.92 cm2 surface area, and 145.56 ng/(g·h) root activity, respectively. (2) The composite lights of 4R1B, 8R1B, 8R1B1P, 6R1B1P1G, and 8R1B1P1G are beneficial for the accumulation of soluble sugar content (SSC) and soluble protein content (SPC), but not conducive for the increase of free proline content (FPC); the plants under 6R1B1P1G and 8R1B1P1G treatments had higher superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) activity and lower malondialdehyde (MDA), polyphenol oxidase (PPO) activity. (3) Redundancy analysis showed that POD activity positively correlated with root activity; SPC, SOD and CAT activities positively correlated with root growth parameters; while SSC, MDA content, APX and PPO activities negatively correlated with root growth parameters. These results suggest that the responses of root growth and antioxidant capacity of the C. lanceolata tissue culture seedlings to different light qualities vary. The relationship between root growth parameters and antioxidant capacity was closely related. Red-blue-purple-green was the most suitable composite light quality for root growth of C. lanceolata tissue culture seedlings, and 8:1:1:1 was the optimal ratio, under which the rooting rate, root activity and root growth of tissue culture seedlings peaked.

Effect of shade level and mulch type on growth, yield and essential oil composition of damask rose (Rosa damascena Mill.) under mid hill conditions of Western Himalayas.

A field experiment was conducted at the experimental farm of CSIR-Institute of Himalayan Bioresource Technology, Palampur, India for two consecutive years (2015-16 and 2016-17). The aim of the study was to test the hypothesis whether different shade level and mulch type would influence the growth, flower yield and essential oil profile of R. damascena. Yield attributes viz., numbers of flowers plant-1, fresh flower weight plant-1, flower yield, and essential oil yield were significantly higher under open sunny conditions as compared to 25% and 50% shade levels. However, plants grown under 50% shade level recorded significantly higher plant height (cm), plant spread (cm) and the lowest numbers of branches as compared to control. Among mulches, black polyethylene mulch recorded significantly higher growth, and yield attributes of damask rose as compared to other mulches. Black polyethylene mulch recorded 74.5 and 39.2% higher fresh flower yield as compared to without mulch, during 2015-16 and 2016-17, respectively. Correlation studies showed a positively significant correlation between quality and quantity traits. A total of twenty-six essential oil compounds were identified which accounted for a total of 88.8 to 95.3%. Plants grown under open sunny conditions along with the applications of black polyethylene mulch produced a higher concentration of citronellol and trans-geraniol. Damask rose planted in open sunny conditions and mulched with black polyethylene sheet recorded significantly higher flower yield.

Effect of ionizing radiation on physiological and molecular processes in plants.

The study of effects of ionizing radiation (IR) on plants is important in relation to several problems: (I) the existence of zones where background radiation - either natural or technogenic - is increased; (II) the problems of space biology; (III) the use of IR in agricultural selection; (IV) general biological problems related to the fundamental patterns and specifics of the effects of IR on various living organisms. By now, researchers have accumulated and systematized a large body of data on the effects of IR on the growth and reproduction of plants, as well as on the changes induced by IR at the genetic level. At the same time, there is a large gap in understanding the mechanisms of IR influence on the biochemical and physiological processes - despite the fact that these processes form the basis determining the manifestation of IR effects at the level of the whole organism. On the one hand, the activity of physiological processes determines the growth of plants; on the other, it is determined by changes at the genetic level. Thus, it is the study of IR effects at the physiological and biochemical levels that can give the most detailed and complex picture of IR action in plants. The review focuses on the effects of radiation on the essential physiological processes, including photosynthesis, respiration, long-distance transport, the functioning of the hormonal system, and various biosynthetic processes. On the basis of a large body of experimental data, we analyze dose and time dependences of the IR-induced effects - which are qualitatively similar - on various physiological and biochemical processes. We also consider the sequence of stages in the development of those effects and discuss their mechanisms, as well as the cause-effect relationships between them. The primary IR-induced physicochemical reactions include the formation of various forms of reactive oxygen species (ROS) and are the cause of the observed changes in the functional activity of plants. The review emphasizes the role of hydrogen peroxide, a long-lived ROS, not only as a damaging agent, but also as a mediator - a universal intracellular messenger, which provides for the mechanism of long-distance signaling. A supposition is made that IR affects physiological processes mainly by violating the regulation of their activity. The violation seems to become possible due to the fact that there exists a crosstalk between different signaling systems of plants, such as ROS, calcium, hormonal and electrical systems. As a result of both acute and chronic irradiation, an increase in the level of ROS can influence the activity of a wide range of physiological processes - by regulating them both at the genetic and physiological levels. To understand the ways, by which IR affects plant growth and development, one needs detailed knowledge about the mechanisms of the processes that occur at the (i) genetic and (ii) physiological levels, as well as their interplay and (iii) knowledge about regulation of these processes at different levels.

Effects of elevated ultraviolet-B radiation on root growth and chemical signaling molecules in plants.

Ozone layer depletion leads to elevated ultraviolet-B (UV-B) radiation, which affects plant growth; however, little is known about the relationship between root growth and signaling molecules in roots. Therefore, in this work, simulated UV-B radiation was used to study the effects of elevated UV-B radiation on root growth of soybean seedlings and changes in the content of signaling molecules in roots. The results showed that compared with the control, the 2.63 kJ m-2 d-1 and 6.17 kJ m-2 d-1 elevated UV-B radiation treatments inhibited root growth, and root growth parameters (total root length, root surface area, root volume, average diameter, root tip number, and root dry weight) all decreased. For root signaling molecules, the content of nitric oxide, reactive oxygen species, abscisic acid, salicylic acid, and jasmonic acid increased, and the content of auxin, cytokinin, and gibberellin decreased. The above indices changed more significantly under the 6.17 kJ m-2 d-1 treatment. After withdrawal of the exposure, the above indices could be restored to a certain extent. These data indicated that UV-B radiation interfered with root growth by affecting the content of signaling molecules in roots, and the degree of the effects was related to the intensity of UV-B radiation. The results from this study provide a theoretical basis for studying the preliminary mechanism of elevated UV-B radiation on root growth and possible pathways that can mitigate UV-B radiation damage for root growth. ONE SENTENCE SUMMARY: The effects of elevated UV-B on root growth of soybean seedlings were regulated by signaling molecules, and the degree of the effects was related to the intensity of UV-B radiation.

Interactive effects of supplemental ultraviolet-B radiation and indole-3-acetic acid on Coleus forskohlii Briq.: Alterations in morphological-, physiological-, and biochemical characteristics and essential oil content.

Ultraviolet (UV)-B radiation and the growth hormone indole-3-acetic acid (IAA) have been known to cause various changes in plants at morphological and physiological levels as individual entities, but their interactive effects on the overall plant performance remain practically unknown. The present study was conducted under near-natural field conditions to evaluate the effects of supplemental (s)-UV-B (ambient+3.6kJm-2day-1) treatment alone, and in combination with two doses of IAA (200ppm and 400ppm) exogenously applied as foliar spray on various growth-, morphological-, physiological-, and biochemical parameters of an indigenous medicinal plant, Coleus forskohlii. Under s-UV-B, the plant growth and morphology were adversely affected (along with reductions in protein- and chlorophyll contents) with concomitant increase in secondary metabolites (as substantiated by an increase in the activities of various enzymes of the phenylpropanoid pathway) and cumulative antioxidative potential (CAP), suggesting the plant's capability of adaptive resilience against UV-B. The essential oil content of the plant was, however, compromised reducing its pharmaceutical value. IAA application at both doses led to a reversal in the effects caused by s-UV-B radiation alone; both the plant growth as well as the essential oil content improved, especially at the higher IAA dose, suggesting its ameliorative role against UV-B induced oxidative stress, and also in improving the plant's medicinal value.

Developmental reprogramming by UV-B radiation in plants.

Plants are extremely plastic organisms with the ability to adapt and respond to the changing environmental conditions surrounding them. Sunlight is one of the main resources for plants, both as a primary energy source for photosynthesis and as a stimulus that regulates different aspects of their growth and development. UV-B comprises wavelengths that correspond to a high energy region of the solar spectrum capable of reaching the biosphere, influencing plant growth. It is currently believed that plants are able to acclimate when growing under the influence of this radiation and perceive it as a signal, without stress signs. Nonetheless, many UV-B induced changes are elicited after DNA damage occurs as a consequence of exposure. In this review we focus on the influence of UV-B on leaf, flower and root development and emphasize the limited understanding of the molecular mechanisms for most of this developmental processes affected by UV-B documented over the years of research in this area.

Radiation exposure of barley seeds can modify the early stages of plants' development.

The reactions of barley seeds (Nur and Grace varieties) in terms of the root and sprout lengths, germination and root mass were studied after γ-irradiation with doses in the range of 2-50 Gy. The dose range in which plants' growth stimulation occurs (16-20 Gy) was identified. It was shown that increased size of seedlings after irradiation with stimulating doses was due to the enhancing pace of development rather than an earlier germination. The activity of the majority of the enzymes studied increased in the range of doses that cause stimulation of seedlings development. The influences of the dose rate, the quality of seeds, their moisture and time interval between irradiation and initiation of germination on the manifestation of the effects of radiation were investigated. The experimental data on the effect of γ-irradiation on seedlings development were significantly better explained by mathematical models that take into account the hormetic effect.

Plant Responses to High Frequency Electromagnetic Fields.

High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and ß-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism.

EFFECTS OF VERY SMALL DOSES OF IONIZING RADIATION AND HYPOMAGNETIC FIELD CHANGE PHYSIOLOGICAL CHARACTERISTICS OF HIGHER PLANT SEEDS.

Effects of a 40-times weakened geomagnetic field and its combination with low a- and y-radiation doses on the physiological characteristics of higher plant seeds and water redox properties were studied. Germination rate was found decreased and seedlings development retarded equally when exposure to the hepomagnetic field was direct or mediated by water. Besides, water-mediated irradiation by low y-doses moderated and by low a-doses augmented the negative HMF effect on seeds growth. In other words, ionizing radiation dominated in this combination. The redox potential of water (ROP) was noted to rise due to low-intensity a-radiation (9Pu) that was nonlinear and polymodal. Comparing to a-irradiation, the range of ROP changes due to y-irradiation ('37Cs) was narrow which was reflected in growth processes in seeds. Water ROP increases as the magnetic field induction attenuates which implies a natural reduction of water molecules internal energy and bettering of water oxidative qualities. In our view, this was the cause for retarded seed germination. Water is believed to be the determinant for the factors in this study as their effects on seeds were modified by changes in water qualities and structure.

Light-hormone interaction in the red-light-induced suppression of photomorphogenesis in rice seedlings.

Red light perceived by the shoot bottom suppresses photomorphogenesis in rice seedlings mediated by phytochrome A. Shoots of these seedlings grown in red light having their shoot bottom exposed were deficient in chlorophyll and accumulated high concentration of trans-zeatin riboside. However, reduced presence of isopentynyl adenosine, dihydrozeatin riboside was observed in shoots of red-light-grown non-green seedlings in comparison to green seedling. The message abundance of cytokinin receptor (OsHK5), transporters (OsENT1, OsENT2), and response regulators (OsRR4, OsRR10) was downregulated in these red-light-grown non-green seedlings. Attenuation of greening process was reversed by application of exogenous cytokinin analogue, benzyladenine, or supplementing red light with blue light. In the same vein, the suppression of gene expression of cytokinin receptor, transporters, and type-A response regulators was reversed in red-light-grown seedlings treated with benzyladenine suggesting that the disarrayed cytokinin (CK) signaling cascade is responsible for non-greening of seedlings grown in red light. The reversal of red-light-induced suppression of photomorphogenesis by blue light and benzyladenine demonstrates the interaction of light and cytokinin signaling cascades in the regulation of photomorphogenesis. Partial reversal of greening process by exogenous application of benzyladenine suggests, apart from CKs perception, transportation and responsiveness, other factors are also involved in modulation of suppression of photomorphogenesis by red light.

Antiphase light and temperature cycles affect PHYTOCHROME B-controlled ethylene sensitivity and biosynthesis, limiting leaf movement and growth of Arabidopsis.

In the natural environment, days are generally warmer than the night, resulting in a positive day/night temperature difference (+DIF). Plants have adapted to these conditions, and when exposed to antiphase light and temperature cycles (cold photoperiod/warm night [-DIF]), most species exhibit reduced elongation growth. To study the physiological mechanism of how light and temperature cycles affect plant growth, we used infrared imaging to dissect growth dynamics under +DIF and -DIF in the model plant Arabidopsis (Arabidopsis thaliana). We found that -DIF altered leaf growth patterns, decreasing the amplitude and delaying the phase of leaf movement. Ethylene application restored leaf growth in -DIF conditions, and constitutive ethylene signaling mutants maintain robust leaf movement amplitudes under -DIF, indicating that ethylene signaling becomes limiting under these conditions. In response to -DIF, the phase of ethylene emission advanced 2 h, but total ethylene emission was not reduced. However, expression analysis on members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase ethylene biosynthesis gene family showed that ACS2 activity is specifically suppressed in the petiole region under -DIF conditions. Indeed, petioles of plants under -DIF had reduced ACC content, and application of ACC to the petiole restored leaf growth patterns. Moreover, acs2 mutants displayed reduced leaf movement under +DIF, similar to wild-type plants under -DIF. In addition, we demonstrate that the photoreceptor PHYTOCHROME B restricts ethylene biosynthesis and constrains the -DIF-induced phase shift in rhythmic growth. Our findings provide a mechanistic insight into how fluctuating temperature cycles regulate plant growth.

Evaluating potential spectral impacts of various artificial lights on melatonin suppression, photosynthesis, and star visibility.

Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies.

A novel mitochondrial DnaJ/Hsp40 family protein BIL2 promotes plant growth and resistance against environmental stress in brassinosteroid signaling.

Plant steroid hormones, brassinosteroids, are essential for growth, development and responses to environmental stresses in plants. Although BR signaling proteins are localized in many organelles, i.e., the plasma membrane, nuclei, endoplasmic reticulum and vacuole, the details regarding the BR signaling pathway from perception at the cellular membrane receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1) to nuclear events include several steps. Brz (Brz220) is a specific inhibitor of BR biosynthesis. In this study, we used Brz-mediated chemical genetics to identify Brz-insensitive-long hypocotyls 2-1D (bil2-1D). The BIL2 gene encodes a mitochondrial-localized DnaJ/Heat shock protein 40 (DnaJ/Hsp40) family, which is involved in protein folding. BIL2-overexpression plants (BIL2-OX) showed cell elongation under Brz treatment, increasing the growth of plant inflorescence and roots, the regulation of BR-responsive gene expression and suppression against the dwarfed BRI1-deficient mutant. BIL2-OX also showed resistance against the mitochondrial ATPase inhibitor oligomycin and higher levels of exogenous ATP compared with wild-type plants. BIL2 participates in resistance against salinity stress and strong light stress. Our results indicate that BIL2 induces cell elongation during BR signaling through the promotion of ATP synthesis in mitochondria.

Phenotypic selection on leaf functional traits of two congeneric species in a temperate rainforest is consistent with their shade tolerance.

Several studies across species have linked leaf functional traits with shade tolerance. Because evolution by natural selection occurs within populations, in order to explain those interspecific patterns it is crucial to examine variation of traits associated with shade tolerance and plant fitness at an intraspecific scale. In a southern temperate rainforest, two climbing plant species coexist but differ in shade tolerance. Whereas Luzuriaga radicans is most abundant in the shaded understory, L. polyphylla typically occurs in intermediate light environments. We carried out an intraspecific approach to test the hypothesis of differential selection patterns in relation to shade tolerance in these congeneric species. The probability of showing reproductive structures increased with specific leaf area (SLA) in L. polyphylla, and decreased with dark respiration in L. radicans. When reproductive output of fertile individuals was the fitness variable, we detected positive directional selection on SLA in L. polyphylla, and negative directional selection on dark respiration and positive directional selection on leaf size in L. radicans. Total light radiation differed between the microsites where the Luzuriaga species were sampled in the old-growth forest understory. Accordingly, L. radicans had a lower minimum light requirement and showed fertile individuals in darker microsites. L. radicans showed lower dark respiration, higher chlorophyll content, and greater leaf size and SLA than L. polyphylla. Results suggest that in more shade-tolerant species, established in the darker microsites, selection would favor functional traits minimizing carbon losses, while in less shade-tolerant species, plants displaying leaf traits enhancing light capture would be selected.

The effects of different UV-B radiation intensities on morphological and biochemical characteristics in Ocimum basilicum L.

BACKGROUND: The effects of short-term ultraviolet B (UV-B) irradiation on sweet basil (Ocimum basilicum L. cv. Cinnamon) plants at the 3-4 leaf pair and flowering stages were examined in controlled environment growth chambers. Plants were exposed to 0 (reference), 2 and 4 kJ UV-B m(-2) day(-1) over 7 days. RESULTS: Exposure of basil plants to supplementary UV-B light resulted in increased assimilating leaf area, fresh biomass and dry biomass. Stimulation of physiological functions in young basil plants under either applied UV-B dose resulted in increased total chlorophyll content but no marked variation in carotenoid content. At the flowering stage the chlorophyll and carotenoid contents of basil were affected by supplementary UV-B radiation, decreasing with enhanced UV-B exposure. Both total antioxidant activity (2,2-diphenyl-1-picrylhydrazyl free radical assay) and total phenolic compound content were increased by UV-B light supplementation. Young and mature basil plants differed in their ascorbic acid content, which was dependent on UV-B dose and plant age. UV-B radiation resulted in decreased nitrate content in young basil plants (3-4 leaf pair stage). CONCLUSION: These results indicate that the application of short-exposure UV-B radiation beneficially influenced both growth parameters and biochemical constituents in young and mature basil plants.