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Background Catechins are crucial in determining the flavour and health benefits of tea, but it remains unclear that how the light intensity regulates catechins biosynthesis. Therefore, we cultivated tea plants in a phytotron to elucidate the response mechanism of catechins biosynthesis to light intensity changes. Results In the 250 μmol·m− 2·s− 1 treatment, the contents of epigallocatechin, epigallocatechin gallate and total catechins were increased by 98.94, 14.5 and 13.0% respectively, compared with those in the 550 μmol·m− 2·s− 1 treatment. Meanwhile, the photosynthetic capacity was enhanced in the 250 μmol·m− 2·s− 1 treatment, including the electron transport rate, net photosynthetic rate, transpiration rate and expression of related genes (such as CspsbA, CspsbB, CspsbC, CspsbD, CsPsbR and CsGLK1). In contrast, the extremely low or high light intensity decreased the catechins accumulation and photosynthetic capacity of the tea plants. The comprehensive analysis revealed that the response of catechins biosynthesis to the light intensity was mediated by the photosynthetic capacity of the tea plants. Appropriately high light upregulated the expression of genes related to photosynthetic capacity to improve the net photosynthetic rate (Pn), transpiration rate (Tr), and electron transfer rate (ETR), which enhanced the contents of substrates for non-esterified catechins biosynthesis (such as EGC). Meanwhile, these photosynthetic capacity-related genes and gallic acid (GA) biosynthesis-related genes (CsaroB, CsaroDE1, CsaroDE2 and CsaroDE3) co-regulated the response of GA accumulation to light intensity. Eventually, the epigallocatechin gallate content was enhanced by the increased contents of its precursors (EGC and GA) and the upregulation of the CsSCPL gene. Conclusions In this study, the catechin content and photosynthetic capacity of tea plants increased under appropriately high light intensities (250 μmol·m− 2·s− 1 and 350 μmol·m− 2·s− 1) but decreased under extremely low or high light intensities (150 μmol·m− 2·s− 1 or 550 μmol·m− 2·s− 1). We found that the control of catechin accumulation by light intensity in tea plants is mediated by the plant photosynthetic capacity. The research provided useful information for improving catechins content and its light-intensity regulation mechanism in tea plant.

Extreme temperature events as a consequence of global climate change result in a significant decline in rice production. A two-year phytotron experiment was conducted using three temperature levels and two heating durations to compare the effects of heat stress at booting, flowering, and combined (booting + flowering) stages on the production of photosynthates and yield formation. The results showed that high temperature had a significant negative effect on mean net assimilation rate (MNAR), harvest index (HI), and grain yield per plant (YPP), and a significant positive effect under treatment T3 on mean leaf area index (MLAI) and duration of photosynthesis (DOP), and no significant effect on biomass per plant at maturity (BPPM), except at the flowering stage. Negative linear relationships between heat degree days (HDD) and MNAR, HI, and YPP were observed. Conversely, HDD showed positive linear relationships with MLAI and DOP. In addition, BPPM also showed a positive relationship with HDD, except at flowering, for both cultivars and Wuyunjing-24 at combined stages. The variation of YPP in both cultivars was mainly attributed to HI compared to BPPM. However, for biomass, from the first day of high-temperature treatment to maturity (BPPT-M), the main change was caused by MNAR followed by DOP and then MLAI. The projected alleviation effects of multiple heat stress at combined stages compared to single-stage heat stress would help to understand and evaluate rice yield formation and screening of heat-tolerant rice cultivars under current scenarios of high temperature during the rice-growing season.

summary Effects of short-term ozone exposure of mature trees were compared with those of seedlings. Both 25-yr-old Douglas firs [Pseudotsuga menziesii (Mirb.) Franco] and 3-yr-old Douglas fir seedlings were exposed to 0, 200 and 400 μgm−1ozone for about 1.5 wk and then labelled with 14CO2 to study the effect on net photosynthesis, translocation and partitioning of assimilates. In the seedling experiment, two identical growth cabinets with separated shoot and root compartments were used for ozone fumigation and 14C-labelling. Seedlings were harvested and HC contents in the needles (subdivided into starch, ethanol-soluble and residue fractions), branches, roots, root/soil respiration and soil residue were determined, together with the total starch content of the needles. Ozone increased the retention of 14C-photosynthates in the needles. Translocation of carbon to the branches and roots seemed to be inhibited by the highest ozone treatment. The increased 14C-retention was mainly recovered in the residue fraction of the needles. Total starch content of the needles decreased in the highest ozone treatment. In the experiment with mature trees, terminal shoots were fumigated with ozone and labelled with 14C using three small branch chambers. Carbon distribution was studied after harvest of the branches. Total 14C contents in the needle fractions and the branches were determined, together with the total starch content of the needles. Ozone was found to inhibit net 14CO2 assimilation as well as translocation of 14C-labelled assimilates from exposed needles to the branch. No effects of ozone were found on the partitioning of 14C among the starch, ethanol-soluble, and residue fractions of the needles, although amounts in the ethanol-soluble fraction tended to increase after exposure to ozone. The results indicate that mature and juvenile Douglas firs respond in a similar way to short-term ozone exposure with regard to carbon translocation. If this similarity also applies to other species, then results from phytotron experiments on ozone and translocation of carbon might gain importance with respect to extrapolation to forest ecosystems.

Yushania niitakayamensis (Bambusoideae; Poaceae), a perennial grass distributed from mid to high elevations in Taiwan, is often found growing in exposed grassland or shaded forest understories. To answer the question how does Y. niitakayamensis cope with contrasting light availability of habitats, we compared (1) leaf ecophysiological traits between populations of Y. niitakayamensis growing in exposed and shaded habitats in four seasons, and (2) plasticity patterns of transplanted plants to two light treatments (full-sun and 70 % shading) in a phytotron. Significant differences in leaf morphological (leaf length, width, specific leaf area, stomatal density), anatomical (leaf thickness (LT), the frequency of cavity formed by collapsed fusoid cells), and biochemical (chlorophyll contents, nitrogen contents per unit area ([N]area) and stable carbon isotope ratio) features were found between populations across seasons. Common garden experiments suggested that most of the trait variations in field growing plants can be explained by the effect of growth light treatment but not by that of population. However, variations between the two populations in LT, [N]area, gas exchange parameters, and the degree of plasticity in LT and [N]area in responding to growth light regimes might have genetic basis. In comparison between transplants from different origins grown under same light regime, plants from the exposed population grown under full-sun expressed significantly higher LT, [N]area and light-saturated photosynthetic rates, whereas plants from the shaded population grown under shading had significantly higher water use efficiency. Accordingly, local specialization in populations of Y. niitakayamensis to particular environmental conditions might have arisen.

Soil salinization adversely affects agricultural productivity. Mitigating the adverse effects of salinity represents a current major challenge for agricultural researchers worldwide. The effects of exogenously applied glycine betaine (GB) and salicylic acid (SA) on mitigating sodium toxicity and improving the growth of cotton seedlings subjected to salt stress remain unclear. The treatments in a phytotron included a control (CK, exogenously untreated, non-saline), two NaCl conditions (0 and 150 mM), four exogenous GB concentrations (0, 2.5, 5.0, and 7.5 mM), and four exogenous SA concentrations (0, 1.0, 1.5, and 2.0 mM). The shoot and roots exposed to 150 mM NaCl without supplementation had significantly higher Na+ and reduced K+, Ca2+, and Mg2+ contents, along with lowered biomass, compared with those of CK. Under NaCl stress, exogenous GB and SA at all concentrations substantially inversed these trends by improving ion uptake regulation and biomass accumulation compared with NaCl stress alone. Supplementation with 5.0 mM GB and with 1.0 mM SA under NaCl stress were the most effective conditions for mitigating Na+ toxicity and enhancing biomass accumulation. NaCl stress had a negative effect on plant growth parameters, including plant height, leaf area, leaf water potential, and total nitrogen (N) in the shoot and roots, which were improved by supplementation with 5.0 mM GB or 1.0 mM SA. Supplementation with 5.0 mM exogenous GB was more effective in controlling the percentage loss of conductivity (PLC) under NaCl stress.

Background Entering and exiting winter dormancy present important trade-offs between growth and survival at northern latitudes. Many forest trees display local adaptation across latitude in traits associated with these phenology transitions. Transfers of a species outside its native range introduce the species to novel combinations of environmental conditions potentially requiring different combinations of alleles to optimize growth and survival. In this study, we performed genome wide association analyses and a selection scan in a P. trichocarpa mapping population derived from crossings between clones collected across the native range and introduced into Sweden. GWAS analyses were performed using phenotypic data collected across two field seasons and in a controlled phytotron experiment. Results We uncovered 584 putative candidate genes associated with spring and autumn phenology traits as well as with growth. Many regions harboring variation significantly associated with the initiation of leaf shed and leaf autumn coloring appeared to have been evolving under positive selection in the native environments of P. trichocarpa. A comparison between the candidate genes identified with results from earlier GWAS analyses performed in the native environment found a smaller overlap for spring phenology traits than for autumn phenology traits, aligning well with earlier observations that spring phenology transitions have a more complex genetic basis than autumn phenology transitions. Conclusions In a small and structured introduced population of P. trichocarpa, we find complex genetic architectures underlying all phenology and growth traits, and identify multiple putative candidate genes despite the limitations of the study population.

Heavy payloads in future shuttle journeys to Mars present limiting factors, making self-sustenance essential for future colonies. Therefore, in situ resources utilization (ISRU) is the path to successful and feasible space voyages. This research frames the concept of planting leafy vegetables on Mars regolith simulant, ameliorating this substrate&rsquo, s fertility by the addition of organic residues produced in situ. For this purpose, two butterhead lettuce (Lactuca sativa L. var. capitata) cultivars (green and red Salanova&reg, ) were chosen to be cultivated in four different mixtures of MMS-1 Mojave Mars simulant:compost (0:100, 30:70, 70:30 and 100:0, v:v) in a phytotron open gas exchange growth chamber. The impact of compost rate on both crop performance and the nutritive value of green- and red-pigmented cultivars was assessed. The 30:70 mixture proved to be optimal in terms of crop performance, photosynthetic activity, intrinsic water use efficiency and quality traits of lettuce. In particular, red Salanova&reg, showed the best performance in terms of these quality traits, registering 32% more phenolic content in comparison to 100% simulant. Nonetheless, the 70:30 mixture represents a more realistic scenario when taking into consideration the sustainable use of compost as a limited resource in space farming, while still accepting a slight significant decline in yield and quality in comparison to the 30:70 mixture.

Fluctuating asymmetry (FA), defined as small, non-directional deviations from perfect symmetry in morphological characters, is often recommended as a handy indicator of environmental stress. A reliance on observational data to provide empirical evidence for the effects of different stressors on FA, in combination with increasing attempts to use FA in environmental research, underscore the need for careful examination of the relationships between environmental stress and FA. We experimentally tested the hypotheses that (i) heavy metal and drought stress increase the leaf FA in plants, and that (ii) plants persisting in heavily polluted sites possess greater stress tolerance and therefore show smaller increases in leaf FA in response to heavy metals than do plants from unpolluted sites. We collected mountain birch, Betula pubescens subsp. czerepanovii, seeds from eight polluted and ten unpolluted sites and reared the seedlings in a sophisticated greenhouse (phytotron). We compared leaf FA between control seedlings, seedlings irrigated with water containing copper and nickel sulphates, and seedlings exposed to drought. Leaf FA showed no response to either heavy metals or drought, despite significant impacts of these treatments on seedling height, leaf size and photosynthetic efficiency. This FA result was independent of the level of pollution at the site of seed origin and consistent for FA values based on low and high accuracy measurements of leaf width, as well as for FA values based on measurements of the widths and areas of leaf halves. Our findings add to accumulating evidence regarding inconsistent relationships between FA and abiotic stress, thereby questioning the indicatory value of FA. We strongly recommend that the use of FA as an indicator of environmental stress be limited to study systems for which the existence of cause-and-effect relationship between the stressing impact and the changes in FA is confirmed by controlled, blinded experiments.

The behaviour of Myrothecium roridum, artificially inoculated on cultivated rocket (Eruca sativa), has been evaluated under eight different temperature and CO2 concentration combinations (from 14-18 °C to 26-30 °C and with 400-450 or 800-850 ppm of CO2). The pathogen isolate used for this study was inoculated on rocket and disease severity increased with high temperatures for both CO2 levels. Verrucarin A and roridin E mycotoxins were produced under all the tested temperatures at high CO2 conditions. The maximum level of verrucarin A was found at 14-18 °C and 800-850 ppm of CO2, and the maximum roridin E production was detected at 26-30 °C with 800-850 ppm of CO2. The results obtained in this study show that both the CO2 concentration and the temperature influence disease severity and mycotoxin production in different ways. An increase in temperature, which is favourable for attacks of the pathogen, could induce the spread of M. roridum in temperate regions, and this pathogen could take on even greater importance in the future, considering its ability to produce mycotoxins.

Background: Vegetable growers in Arctic areas must increasingly rely on market strategies based on regional origin and product quality. Swede roots (rutabaga) were grown in a phytotron to investigate the effect of high latitude light conditions on sensory quality and some health and sensory-related compounds. Experimental treatments included modifications of 24 h natural day length (69° 39' N) by moving plants at daily intervals to dark chambers with either no light, fluorescent growth light and/or low intensity photoperiod extension.; Results: Shortening the photosynthetic light period to 12 h produced smaller roots than 15.7 h and 18 h, with highest scores for bitter and sulfur taste, and lowest scores for sweetness, acidic taste and fibrousness. The photoperiod in combination with the photosynthetic light period also had an influence on glucosinolate (GLS) contents, with lowest concentrations in 24 h natural light and highest in 12 h natural light. Concentrations of vitamin C, glucose, fructose and sucrose were not significantly influenced by any of the treatments.; Conclusion: High latitude light conditions, with long photosynthetic light periods and 24 h photoperiod, can enhance sweet/less bitter taste and reduce GLS contents in swede roots, compared to growth under short day conditions. This influence of light conditions on eating quality may benefit marketing of regional products from high latitudes. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

To counter the threat of drought, which is expected to increase in the future, we analyzed the combined effects of elevated carbon dioxide (CO2) concentration and drought on the photosynthetic apparatus and morphological traits in seedlings of yellow poplar (Liriodendron tulipifera). The plants were grown for four months in a phytotron under different CO2 concentrations [ambient CO2, 430 ppm, AC) and elevated CO2, 640 ppm, EC] and water treatment [field capacity, FC and 50% of field capacity, FC50]. FC50 was sufficient for inducing a reduction in the photosynthetic rate of L. tulipifera. However, under FC50 combined with EC, we observed an increase in photosynthetic rate with increased photopigment content, photochemistry efficiency, and light harvesting ability. Further, decreased specific leaf area and increased wax coverage in EC suggested that EC contributed to protect chloroplasts and reduce water loss. In conclusion, functional improvements of the photosynthetic apparatus with changes in morphological traits were observed under FC50 combined with EC and EC ameliorated the adverse effect of FC50 on the seedlings of L. tulipifera.

Ex-situ cultivation of biological soil crusts (biocrusts) is a promising technology to produce materials that can induce the recovery of biocrusts in the field for the purposes of preventing soil erosion and improving hydrological function in degraded ecosystems. However, the ability of artificially cultivated biocrusts to survive under adverse field conditions, including drought and heat stresses, is still relatively unknown. Mosses can bolster biocrust resistance to the stresses (e.g., drought and heat) and the resistance may be introduced prior to field cultivation. In this study, we subjected the well-developed artificial moss biocrusts (dominant species of Didymodon vinealis (Brid.) Zand.) that we cultivated in the phytotron to a dehydration-rehydration experiment and also a heat stress experiment and measured the activities of protective enzymes (including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT)) and the contents of osmoregulatory substances (including soluble proteins and soluble sugars) and malondialdehyde (MDA, an indicator of oxidative stress) in the stem and leaf fragments of mosses. The results showed that, during the dehydration process, the activities of protective enzymes and the contents of osmoregulatory substances and MDA gradually increased with increasing duration of drought stress (over 13 days). During the rehydration process, values of these parameters decreased rapidly after 1 d of rehydration. The values then showed a gradual decrease for 5 days, approaching to the control levels. Under heat stress (45°C), the activities of protective enzymes and the content of soluble proteins increased rapidly within 2 h of heat exposure and then decreased gradually with increasing duration of heat exposure. In contrast, the contents of soluble sugars and MDA always increased gradually with increasing duration of heat exposure. This study indicates that artificial moss biocrusts possess a strong drought resistance and this resistance can be enhanced after a gradual dehydration treatment. This study also indicates that artificial moss biocrusts can only resist short-term heat stress (not long-term heat stress). These findings suggest that short-term heat stress or prolonged drought stress could be used to elevate the resistance of artificial moss biocrusts to adverse conditions prior to field reintroduction.

Gutierrez, W. A., and Shew, H. D. 2000. Factors that affect development of collar rot on tob acco seedlings grown in greenhouses. Plant Dis. 84:1076-1080. Collar rot, caused by Sclerotinia sclerotiorum, is an important disease of tobacco transplants produced under greenhouse conditions. Factors that affect the development of the disease were studied, including age of seedlings, presence of an external source of nutrients (leaf extract), clipping (leaf removal) practices, exposure to low temperature, and leaf injury caused by heat and a chemical. Flue-cured tobacco seedlings, cultivar K- 326, were grown in polystyrene cell trays floating on a nutrient solution. Trays were maintained in a phytotron growth chamber with a 28/18°C day/night temperature regime. Seedlings were inoculated with ascospores of S. sclerotiorum at the desired stage of growth by placing mature apothecia in the growth chamber and inducing ascospore release and deposition. Disease incidence was determined by examining seedlings for the presence of stem lesions over the next 15 to 21days. Seedlings between 35 and 53 days old were more susceptible to collar rot than younger or older seedlings. Inoculum efficiency was highest and disease was most severe when an external source of nutrients was present on leaf surfaces. Clipping of leaf tips did not increase disease, but if the leaf pieces created by clipping were left on seedlings, collar rot development was enhanced compared with treatments where debris was removed. Heat and chemical injuries that resulted in necrotic tissue provided highly susceptible infection courts for ascospores of S. sclerotiorum, but exposure to low temperature, which caused no visible injury, did not enhance infection. Adoption of cultural practices that minimize accumulation of leaf debris and eliminate factors that cause necrotic injury on leaves should greatly reduce the severity of collar rot of tob acco seedlings.

In this study, typical moss crusts, which were dominated by the species Didymodon vinealis (Brid.) Zand., were collected from the Loess Plateau and a 65-day cultivation experiment was performed to study the effects of five kinds of nutrient solutions (Knop, Murashige-Skoog (MS), Benecke, Part and Hoagland), two kinds of carbohydrates (glucose and sucrose) and three kinds of plant growth regulators (thidiazuron (TDZ), 6-benzylaminopurine (6-BA) and naphthaleneacetic acid (NAA)) on the coverage, plant density, and plant height of moss crusts. The main conclusions are as follows. (1) All Knop, MS, Benecke, Part and Hoagland nutrient solutions improved the coverage and plant density of moss crusts to different degrees and the promotional effects of the Hoagland nutrient solution were most significant. (2) Glucose and sucrose could promote the formation of moss crusts, but they inhibited the development of moss crusts at concentrations greater than 10 g/L. (3) With an increase in concentration, the effects of TDZ on the development of moss crusts changed from "enhanced" to "inhibited". Regardless of whether the concentration was high or low, 6BA had no significant effects on the growth of moss crusts, and NAA reduced the development of moss crusts. Results suggest that nutrient solutions (e.g. Hoagland), low concentration carbohydrates solutions, and some plant growth regulators (e.g. 1 mg/L TDZ) enhance the development of moss crusts in Loess Plateau under the appropriate environmental conditions.

BACKGROUND Marked effects of the climatic environment on fruit chemical composition have often been demonstrated in field experiments. However, complex covariations of several climatic factors in the natural environment complicate the interpretation of such experiments and the identification of the causal factors. This can be better achieved in a phytotron where the various climatic factors can be varied systematically. Therefore, we grew four black currant cultivars of contrasting origin in a phytotron under controlled post-flowering temperature and photoperiod conditions and analysed the berries for their ascorbic acid, sugar and organic acid contents. RESULTS The analyses revealed significant effects of genotype on all investigated compounds. Particularly large cultivar differences were observed in the concentrations of l-ascorbic acid (AA) and sucrose. The concentrations of both AA and dehydroascorbic acid (DHAA), as well as the concentrations of all major sugars, decreased consistently with an increasing temperature over the temperature range 12–24 °C. Fructose and glucose were the predominant sugars with concentrations several fold higher than that for sucrose. AA was the main contributor to the total ascorbate pool in black currant berries. The AA/DHAA ratio varied from 5.6 to 10.3 among the studied cultivars. The concentration of citric acid, which was the predominant organic acid in black currant berries, increased with an increasing temperature, whereas the opposite trend was observed for malic and shikimic acid. Quninic acid was always present at relatively low concentrations. By contrast, photoperiod had no significant effect on berry content of any of the investigated compounds. CONCLUSION It is concluded that the post-flowering temperature has marked effects on the concentration of important chemical compounds responsible for taste and nutritional value of black currant berries, whereas photoperiod has no such effect in the studied cultivars. © 2016 Society of Chemical Industry

The effects of postflowering temperature and daylength on the concentration of individual phenolic compounds were studied in black currant (Ribes nigrum L.) berries under controlled phytotron conditions. The four cultivars studied varied greatly in their concentrations of individual phenolic compounds and temperature stability for accumulation. The concentrations of a wide range of identified phenolic compounds were strongly influenced by temperature over the 12-24 °C range, often with opposite temperature gradient patterns for compounds within the same subclass. Accumulation of anthocyanins and flavonols increased under natural long day conditions, which provided an increased daily light integral, while under identical light energy conditions, photoperiod had little or no effect on the concentration of phenolic compounds. Furthermore, with the exception of members of the hydroxycinnamic acid subclass, the concentration of most phenolic compounds was higher in berries ripened outdoors than in the phytotron, apparently due to screening of UV-B radiation by the glass cover.

We measured leaf photosynthetic traits in shade-grown seedlings of four tree species native to northern Japan, raised under an elevated CO2 condition, to investigate the effects of elevated CO2 on shade tolerance of deciduous broadleaf tree species with different successional traits. We considered Betula platyphylla var. japonica and Betula maximowicziana as pioneer species, Quercus mongolica var. crispula as a mid-successional species, and Acer mono as a climax species. The plants were grown under shade conditions (10% of full sunlight) in a CO2 -regulated phytotron. Light compensation points (LCPs) decreased in all tree species when grown under elevated CO2 (720 μmol·mol(-1) ), which were accompanied by higher apparent quantum yields but no photosynthetic down-regulation. LCPs in Q. mongolica and A. mono grown under elevated CO2 were lower than those in the two pioneer birch species. The LCP in Q. mongolica seedlings was not different from that of A. mono in each CO2 treatment. However, lower dark respiration rates were observed in A. mono than in Q. mongolica, suggesting higher shade tolerance in A. mono as a climax species in relation to carbon loss at night. Thus, elevated CO2 may have enhanced shade tolerance by lowering LCPs in all species, but the ranking of shade tolerance related to successional traits did not change among species under elevated CO2 , i.e. the highest shade tolerance was observed in the climax species (A. mono), followed by a gap-dependent species (Q. mongolica), while lower shade tolerance was observed in the pioneer species (B. platyphylla and B. maximowicziana).

High temperature stress influences pollen grains development in upland cotton (Gossypium hirsutum L.) anthers, resulting in anthers with an abnormal structure and pollen grains with a low germination rate. To examine the thermotolerance mechanisms of pollen grains in upland cotton, we observed pollen germination rates, pollen grain ultrastructure, anther structure, and the expression of heat shock protein (HSP) genes in pollen grains after the plants were continuously exposed to high temperatures (36/30°C) in a phytotron for 8 h every day over a period of 10 d. After the high-temperature treatment, the pollen germination percentage of the heat-sensitive cultivar was reduced compared with the heat-tolerant cultivar, and the structure of indehiscent anthers and the ultrastructure of pollen grains in the heat-sensitive cultivar were more abnormal than that in the heat-tolerant cultivar. There were more abnormal mitochondria, endoplasmic reticulum, and vacuoles as well as fewer starch granules in the pollen grains of the heat-sensitive cultivar compared with the heat-tolerant cultivar. The deformation of the pollen grain architecture may influence the pollen germination rate. The expression of the GhHSP90, GhHSP2, GhHSP7, and GhHSP8 genes was up-regulated to a greater extent in the heat-sensitive pollen grains compared with the heat-tolerant pollen during and after the high temperature period. The up-regulation of HSP gene expression may protect pollen grains from damage under high temperature stress (36/30°C). The structure of the anthers, ultrastructure of the pollen grains, and expression of HSP genes are related to the thermotolerance of pollen grains. These results provide a new approach for screening upland cotton cultivars for thermotolerance.

The influence of weak permanent horizontal magnetic field (PMF, field strength ∼400 A/m) on lipid peroxidation was studied with 5-day-old radish (Raphanus sativus L. var. radicula D.C.) seedlings grown in a phytotron at 18–20℃ under illuminance of 1–6 klx and in darkness. Seedlings raised at geomagnetic field (GMF) were used as the reference (control) sample. Under the action of PMF, the largest content of a terminal lipid peroxidation product, MDA was observed in seedlings grown at illuminance of 2–3 klx. No clear dependence of MDA accumulation on light intensity during seedling growth was observed. The action of PMF altered the proportion between light and dark reactions of lipid peroxidation; lipid peroxidation decreased in the magnetic field. During seed germination under the action of PMF, the content of MDA was found to decrease: the largest decrease was observed in 5-day-old seedlings at illuminance of 1 klx. The permanent magnetic field acted as a correcting factor by affecting the MDA content.

The influence of 3 temperatures: 4°, 13°, and 22°C and of 3 humidities 50% r.h., 77% r.h. and 95% r.h. on the effectiveness of two defolians KJ and Mg(ClO3)2•6H2O was investigated in a phytotron. By changing day and night temperature and humidity the weather conditions encountered in nurseries in autumn were simulated. The influence of environment on defoliation depended markedly on the species of plant and on the defoliant. In several cases defoliation started earliest at 13° but over a longer period of time the temperature 4° stimulated markedly leaf shedding.

The behavior of Myrothecium verrucaria, artificially inoculated on spinach, was studied under seven different temperature conditions (from 5 to 35 °C) and under eight different combinations of temperature and CO2 concentration (14–30 °C and 775–870 or 1550–1650 mg/m3). The isolate used for this study was growing well on spinach, and the mycotoxins verrucarin A and roridin E were produced under all tested temperature and CO2 conditions. The maximum levels of verrucarin A (18.59 ng/g) and roridin E (49.62 ng/g) were found at a temperature of 26–30 °C and a CO2 level of 1550–1650 mg/m3. Rises in temperature as well as in temperature and CO2 concentrations had a significant effect by increasing Myrothecium leaf spots on spinach. The biosynthesis of verrucarin A was significantly increased at the highest temperature (35 °C), while roridin E was influenced by the CO2 concentration. These results show that a positive correlation between climate condition and macrocyclic trichothecene production is possible. However, because of the ability of M. verrucaria to produce mycotoxins, an increase in temperature could induce the spread of M. verrucaria in temperate regions; this pathogen may gain importance in the future.

Increasing the number of flowers and pods set, as well as reducing the intensity of their abortion, is of crucial importance for the yielding of leguminous plants. This study examined the effects of the type of soil used and mineral fertilization applied on the generative development of the traditional and self-completing (restricted branching) cultivars of white lupin (Lupinus albus L.), yellow lupin (L. luteus L.) and narrow-lafed lupin (L. angustifolius L.) cultivated under controlled phytotron conditions. Experiments carried out under such conditions allow for the elimination of variable environmental factors affecting the course of plant ontogenesis in field cultivation, and enable unambiguous interpretation of the biochemical and molecular influence of a selected factor on the physiological process studied. For the first time, the influence of different cultivation factors on generative development of traditional and selfcompleting (restricted branching) cultivars of lupins under phytotrone was examined. The research results presented here indicate that each of the selected lupin cultivars has its own characteristic cultivation conditions that are optimal for its generative development. The largest number of flowers were formed by the traditional cultivars of L. luteus and L. angustifolius, as well as the self-completing (restricted branching) cultivars of L. luteus and L. albus grown in class IIIa soil material. The lowest flower abortion rate was observed in L. albus grown in class V soil material, in L. luteus grown in class IIIa soil material, and in L. angustifolius grown in class IVa soil material. Regardless of the cultivation conditions applied, in all of the lupin cultivars examined the first pods to be set were characterized by the lowest abortion rate. The results obtained allowed for the development of lupin phytotron cultivation models for the purposes of research on generative development control.

O objetivo deste trabalho foi avaliar a biologia e a tabela de vida de fertilidade do pulgão-preto da videira [Aphis illinoisensis (Hemiptera: Aphididae)], em mudas das cultivares de Vitis labrusca Bordô, e de V. vinifera Cabernet Franc, Itália e Moscato Bianco. O experimento foi conduzido em 50 minigaiolas de confinamento, com um inseto em cada gaiola por tratamento, fixadas em mudas de videira mantidas em câmara de crescimento do tipo fitotron (a 25±1°C, umidade relativa de 75±10% e fotófase de 14 horas). Avaliaram-se diariamente a duração e a viabilidade ninfal, a fecundidade e a longevidade do período reprodutivo da espécie. O pulgão-preto da videira completou o ciclo biológico nas mudas das mencionadas cultivares, com duração da fase de ninfa de 7,9±0,3, 6,8±0,2, 6,2±0,2 e 6,7±0,2 dias, e viabilidade de 58, 82, 98 e 80% para 'Bordô', 'Cabernet Franc', 'Itália' e 'Moscato Bianco', respectivamente. 'Cabernet Franc' e 'Moscato Bianco' foram mais favoráveis ao desenvolvimento do pulgão-preto, com base na tabela de vida de fertilidade, com 51,3 e 55,6 descendentes por fêmea, por geração, respectivamente. 'Bordô' foi a menos adequada ao desenvolvimento do afídeo, com 12,55 descendentes por fêmea, por geração, o que indica resistência do tipo antibiose ou não preferência do inseto pela cultivar.

One of the critical points of Douglas fir seedling production is to optimize the time of sowing and length of pre-sowing treatment. Germination and emergence of Douglas fir seed lot of the Czech origin (CZ-2-2A-DG-1740- 6-3-P) were observed in simulated warm and cold conditions in two phytotrons for 3 months. Before this procedure the seeds were exposed to different prechilling duration. The temperature in control conditions of phytotrons was stable for 28 days and then it was increased: 11, 13, 17°C in cold phytotron and 13, 17, 20°C in the warm phytotron. Seeds without stratification and stratified for 3, 5, 7, 9 and 16 weeks were tested. The laboratory germination capacity of non-stratified seeds was only 58% and it was significantly ( P < 0.05, Tukey's test) lower than in stratification treat- ments when it varied from 92% to 96%. Non-stratified seeds did not germinate in cold phytotron and they germinated very slowly (germination rate at the end of experiment was 7%) in warm phytotron. The germination capacity of seeds both in the phytotron and in the laboratory was observed in treatments with prechilling of seeds longer than 7 weeks in warm conditions and only for seeds after 16 weeks of prechilling in cold conditions. The highest emergence rate of seeds (84%) was found in the warm phytotron after 16 weeks of stratification. Comparable results were reached only for 9 weeks of stratification in the same phytotron. The results suggest that the prolongation of the standard 3-week prechilling period helps to increase germination capacity and emergence rate of seeds. Future research should focus on optimal length with regard to more seed lots and also on seedling quality parameters.

The flavonoids content and its composition in Ginkgo (Ginkgo biloba L.) leaves are affected by environmental factors such as temperature and soil moisture. Here we performed experiments in phytotron using 2-year-old Ginkgo seedlings to explore the effects of temperature and soil moisture on flavonoids content, enzymes related to flavonoids biosynthesis such as phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and p-coumarate CoA ligase (4CL), soluble sugar and protein content. We found that temperature and lower soil moisture had significant effects on these parameters. The effects of temperature on flavonoids content, the activity of C4H and 4CL and soluble sugar content were greater than that of soil moisture. The total flavonoid content, the activity of PAL, C4H and 4CL, soluble sugar content were higher in lower temperature regime 15 °C (daytime)/5 °C (nighttime) and lower soil moisture (30–35 % of field capacity), but higher temperature was beneficial to the accumulation of soluble protein. This indicates that increasing of soluble sugar content and the activity of PAL, C4H and 4CL are beneficial to flavonoids biosynthesis and accumulation in the Ginkgo leaves, while increasing of soluble protein is adverse to flavonoids biosynthesis. Because lower temperature and soil moisture are favorable to flavonoids biosynthesis, we can take some silvicultural steps to increase flavonoids production in Ginkgo plantation, such as establishing leaf-harvest plantation at lower temperature zone, reducing irrigating before harvesting leaves.

In Hokkaido, northern Japan, soybean [Glycine max (L.) Merr.] crops are damaged by cold weather. Chilling temperatures result in the appearance of cracking seeds (CS) in soybean crops, especially those grown in eastern and northern Hokkaido. Seed coats of CS are severely split on the dorsal side, and the cotyledons are exposed and frequently separated. CS occurrence causes unstable production because these seeds have no commodity value. However, little is known about the CS phenomenon. The aims of this study were to identify the cold-sensitive stage associated with CS occurrence and to develop a method to select CS-tolerant lines. First, we examined the relationship between chilling temperatures after flowering and CS occurrence in field tests. The average temperature 14 to 21 days after flowering was negatively correlated with the rate of CS. Second, we evaluated differences in CS tolerance among soybean cultivars and breeding lines in field tests. ‘Toyohomare’ and ‘Toiku-238’ were more CS-tolerant than ‘Yukihomare’ and ‘Toyomusume’. Third, we developed a selection method in which plants were subjected to 21-day chilling-temperature treatment from 10 days after flowering in a phytotron. This enabled comparisons of CS tolerance among cultivars. This selection method will be useful for breeding CS-tolerant soybeans.

An investigation was carried out to understand the physiological mechanisms of male sterility in rice. The critical sterility temperature and critical stage of thermosensitivity of the selected TGMS (Thermosensitive Genie Male Sterile) line, TS 29 was studied using a Phytotron. Variations in the physiological traits were analyzed at Stage VII of panicle development (Filling phase of pollen, floret and panicle reach full length and colour turns to green). High significant reductions in photosynthetic rate, transpiration rate, hill reaction, sugars and carbohydrate contents were recorded. The high temperature induced male sterility in TGMS line was associated with accumulation of starch and higher diffusive resistance. However a reverse of all the above responses was found in the TS 29 grown under fertility inducing low temperature and in the variety CO 46. The results revealed that some physiological traits play an important role by acting as signals or messengers in response to temperature leading to pollen abortion.

Nanomaterials are finding widespread applications in industry, agriculture and environment due to their unique properties. But, before these materials are widely in use, their impact on soil ecology needs to be thoroughly investigated. In addition, how the nanoparticles behave in soil under elevated CO2 is unknown. A pot culture experiment was conducted under controlled conditions in phytotron to study the effect of nanoparticles on microbial biomass and enzyme activity in soil under rice crop at ambient and elevated atmospheric CO2. Manufactured nanoparticles of Fe and Zn (n-Fe2O3 and n-ZnO) were added to soil at concentrations of 100, 500 and 1,000 mg kg−1. FeSO4 (11.1 mg kg−1), ZnSO4 (5.33 mg kg−1) and ‘control’ treatments were also included for comparison. Results showed highest bacterial population at 100 mg kg−1 n-Fe2O3, which significantly decreased at 500 and 1,000 mg kg−1 n-Fe2O3 or n-ZnO. Similarly the dehydrogenase activity is significantly higher with 100 mg kg−1 n-Fe2O3 as compared to control and FeSO4 or ZnSO4. As compared to 100 mg kg−1 concentration, there was twofold to fivefold decrease in fluorescein diacetate activity at 500 and 1,000 mg kg−1 of nano-Fe2O3 treatment. At elevated CO2, the microbial biomass and activities were higher at tillering than panicle initiation of rice crop over ambient CO2 with 100 mg kg−1 n-Fe2O3 and ZnO than other treatments. It is concluded that n-Fe2O3 and n-ZnO at 100 mg kg−1 is effective to maintain various soil microbiological process but at higher concentrations (e.g., 500 and 1,000 mg kg−1) negative impacts on soil ecology can be expected.

In the last decades, several studies have reported the increase of land degradation and desertification in the Mediterranean Basin. Depending on degradation severity, ecological restoration might be needed in order to promote ecosystem recovery. The ecology of the selected species and intra specific variability should be considered in order to improve restoration options, especially facing climate change. The present study tested the hypothesis that seedlings from drier provenances would be better adapted to low water content conditions. Seeds were germinated under controlled temperature after which seedlings were grown in a phytotron under two contrasting watering regimes. Seedling performance was analysed using morphological and physiological parameters. Low water content had a clear negative effect on the seedlings’ aboveground biomass (total dry weight, root collar diameter, leaf dry weight and leaf weight ratio) and a positive effect on belowground biomass (root weight and root:shoot ratio). This response was not unequivocal, since provenances differed in morphological adaptations to low water content. Seedlings from the wettest provenance revealed a higher relative growth rate under high water content but a poor adaptation to limited water availability when compared to the other two provenances. This was observed by the absence of a significant belowground investment in this provenance. Seedlings from the wettest provenance also presented a significant reduction of total leaf area that was not observed in the other two provenances. This can however be hardly considered as a successful adaptation to cope with drought since this provenance produced less sclerophyllous leaves, less belowground biomass and also lower sapwood to leaf area ratio independently from the water content conditions. By contrast, seedlings from the dry provenance with the hottest summer had similar root collar diameter, leaf dry weight and physiological performance under both watering regimes. The observed adaptations to water regimes seem to be related with the climate of the seed source and highlighted the importance of seed provenance in ecological restoration actions using Mediterranean species. This knowledge could improve early establishment success predictions for different plant populations, allowing more reliable and cost-effective management decisions under climate change scenarios.

Tomato serves as a model to introduce agronomically important genes into dicotyledonous crop plants and to develop edible vaccines and produce cost-effective therapeutics. This study has developed an efficient protocol of shoot organogenesis for Lycopersicon esculentum Mill. through using of different types of explants and growth regulators. Generally, all explants responded significantly to presence of BAP. Best shoot regeneration for leaf (100%) was achieved on MS supplemented with BAP (2 mg/L) + IAA (0.1 mg/L), whereas it was recorded on MS supplemented with BAP (2 mg/L) and BAP (2 mg/L) + IAA (0.5 mg/L) for cotyledons (95%). In addition, hypocotyls (77%) showed the best shoot response on MS supplemented BAP (3 mg/L). Highest number of shoots per explant was 13.33, 12.25, 7.94 respectively for hypocotyls, leaves, cotyledons. The best medium for highest length of shoot was in the presence of BAP (3 and 2 mg/L) + IAA (0.1 mg/L) respectively for hypocotyl (45 mm) and leaf (40.50 mm) explants. This parameter was achieved for cotyledons (13.32 and 12.5 mm) on MS medium supplemented with BAP (3 and 2) mg/L + IAA (0.1 mg/L), respectively. The increasing of BAP concentration up to 3 (mg/L) causes shoot length to continue developing, but it fell down in the presence of BAP (4 mg/L) due to the toxic effect of growth regulators accumulation. Root formation took place within 10–14 days after culturing on the rooting media. Best root induction (100%) was observed on MS medium supplemented with IAA (0.1 and 0.2 mg/L). All rooted shoots acclimated in phytotron and then cultivated in the greenhouse.

Not only in the Czech Republic there is a problem with low yield of Douglas fir seedlings in forest tree nurseries. It can be caused mainly by two factors: the type of pre-sowing treatment and the temperature at the time of sowing. The aim of this study is to find out their influence on the emergence rate of Douglas fir. We have tested one specific seed lot originated from the Czech Republic subject to the following variants of pre-sowing treatment: soaking for 48 hours, stratification without a medium for 21 days and for 30 days after 48 hours of soaking and stratification for 30 days with a medium. The treated seeds were sown in a phytotron at temperatures of 13/8 °C – 10/14 hours (day/night) (simulation of early sowing season in February or March) and at temperatures of 17/13 °C – 14/10 hours (simulation of late sowing season in May). In case of the early sowing season, approximately half of the germinable seeds emerged in all treatment variants including the control variant (seeds without stratification). The late sowing season resulted in different emergence rate of the seeds that were subject to different variants of pre-sowing treatment (24–51 %). Then, 21day and 30day stratification were not sufficient for the tested conditions of the early and late sowing season. None of the combinations of pre-sowing treatment and sowing time resulted in full use of the seed potential of the tested seed lot.

In this study, the resistance to ozone and characteristics of ozone-induced damage were investigated on the perennial ground cover plant species. Sedum kamtschaticum and Hosta longipes were exposed to 200 μg·kg -1 ozone for 8 hours per day (from 08:00 to 16:00) in the naturally irradiated phytotron. The extent of ozone-induced damage was measured through the analysis of physiological parameters, such as water use efficiency (WUE), chlorophyll content (Chl. a, Chl. b, Chl. a + b, and Chl. a/b ratio), carotenoid contents, and the induction of reactive oxygen species (ROS). Ozone exposure significantly reduced the daytime WUE in both species. The contents of chlorophyll and carotenoid were also decreased and ROS, such as hydrogen peroxide (H2O2) and superoxide radical (O2 - ) were accumulated after ozone exposure. The above results of this study suggested that S. kamtschaticum is more resistant to atmospheric ozone than Hosta longipes. Considering its fast responses to ozone, it was also assumed that Hosta longipes can be used as an indicator plant of an increase in atmospheric ozone concentration.

Olive tree (Olea europaea L.) is an important crop in the Mediterranean Basin where drought and salinity are two of the main factors affecting plant productivity. Despite several studies have reported different responses of various olive tree cultivars to salt stress, the mechanisms that convey tolerance and sensitivity remain largely unknown. To investigate this issue, potted olive plants of Leccino (salt-sensitive) and Frantoio (salt-tolerant) cultivars were grown in a phytotron chamber and treated with 0, 60 and 120 mM NaCl. After forty days of treatment, growth analysis was performed and the concentration of sodium in root, stem and leaves was measured by atomic absorption spectroscopy. Phenolic compounds were extracted using methanol, hydrolyzed with butanol-HCl, and quercetin and kaempferol quantified via high performance liquid-chromatography-electrospray-mass spectrometry (HPLC-ESI–MS) and HPLC-q-Time of Flight-MS analyses. In addition, the transcripts levels of five key genes of the phenylpropanoid pathway were measured by quantitative Real-Time PCR. The results of this study corroborate the previous observations, which showed that Frantoio and Leccino differ in allocating sodium in root and leaves. This study also revealed that phenolic compounds remain stable or are strongly depleted under long-time treatment with sodium in Leccino, despite a strong up-regulation of key genes of the phenylpropanoid pathway was observed. Frantoio instead, showed a less intense up-regulation of the phenylpropanoid genes but overall higher content of phenolic compounds. These data suggest that Frantoio copes with the toxicity imposed by elevated sodium not only with mechanisms of Na+ exclusion, but also promptly allocating effective and adequate antioxidant compounds to more sensitive organs.

In order to investigate the relationship between environmental conditions and vegetative growth and reproductive development in the strawberry, freshly rooted runner plants of the cultivar ‘Sonata’ were grown in a phytotron at temperatures of 12, 18 and 24 °C and photoperiods of 10 h short day (SD) and 20 h long day (LD) for 31 d and harvested at 10 d intervals. Plant dry weight and leaf area increases were exponential versus time, giving a linear regression with the natural log (ln). This rendered the relative growth rate (RGR) constant over time at each environmental condition. Over the entire 31 d growth period, the RGR increased linearly with increasing temperature across the range of temperatures with a further 10–13% enhancement by LD. A maximum RGR value of 0.077 g/g/d was determined in LD at 24 °C. Increases in the RGR was driven by a combined increase in net assimilation rate (NAR) and leaf area ratio (LAR) and was associated with an increased allocation of dry matter production into leaves and less into crowns and roots. Because of this, the shoot/root ratio increased consistently with increasing temperature and photoperiod, which was also associated with a significant increase in the tissue C/N concentration ratio. Low temperature promoted starch accumulation markedly in all parts of the plants, with a further enhancement by LD conditions, while the concentrations of soluble sugars were less affected by the climatic environment. Forcing of plants exposed to the various growth conditions for 31 d showed that all plants at 12 and 18 °C and 80% of those at 24 °C had initiated flowers in SD, whereas none had initiated flowers in LD regardless of temperature conditions. All these results demonstrate an opposite environmental relationship between vegetative growth and reproductive development in the strawberry.

This study was carried out to investigate the effect of artificial light sources with different light qualities on the growth and flowering characteristics of a herbaceous long-day plant, Petunia × hybrida Hort. Seedlings of petunia cultivar ‘Madness Rose’ were potted, acclimated for one week, and grown in a phytotron equipped with tube- and bulb-type fluorescent lamps (FL tube and bulb), tube-type white light-emitting diodes (LED tube), halogen lamps (HL), metal halide lamps (MH), and high pressure sodium lamps (HPS) for 10 weeks. The temperature, photoperiod, and photosynthetic photon flux density (PPFD) in the phytotron were 22 ± 2℃, 16 h, and 25 ±2 μmolㆍm -2 ㆍs -1 , respectively. Light sources combined with HL promoted stem elongation, and plant height and internode length decreased with increasing red to far-red (R:FR) ratio. FL tube + LED tube, HPS, and FL tube promoted branching, whereas plants grown under light sources combined with HL did not have any branches. Days to flowering (from longest to shortest) occurred as follows: FL tube + HL > FL tube + HL > MH > HPS = FL tube + FL bulb > FL tube + LED tube > LED tube > FL tube, indicating that reducing the R:FR ratio of the light sources promoted flowering. Only 20% of plants grown under an FL tube flowered, whereas under all other treatments, 100% of plants flowered. At 10 weeks after treatment, plants grown under HPS and MH had (cumulatively) 12 open flowers, and those grown under FL tube + FL bulb, LED tube, FL tube + LED tube, and HPS treatment had approximately seven flower buds. These results suggest that light sources with low R:FR ratios promote flowering and stem elongation in petunia, but they reduce its ornamental value due to overgrowth and poor branching.

The aim of the study was to the assess the influence of Ca/Mg ions ratio on the photosynthetic activity of Salix viminalis L. ‘Cannabina’ plants cultivated in medium enriched with Cu(NO3)2. The experiment was conducted in controlled conditions in a phytotron for 21 days; hence the early plant response was tested. Plants were cultivated with different Ca/Mg ions ratios, i.e. (4:1)l, (4:1)h, and 1:10. Plants were additionally treated with Cu(NO3)2 at 1, 2, and 3 mM concentration in cultivation medium. Net photosynthetic rate, stomatal conductance and transpiration were measured after the first, second and third week of cultivation. Additionally, chlorophyll content, leaf morphology, root biomass and copper accumulation in leaves and roots were investigated. The investigations revealed differences in plant response to particular treatments — differences in Cu accumulation for particular Ca/Mg ions ratios were detected. It seems that plants are adapted to high Cu2+ concentrations, when 1:10 Ca/Mg ions ratio is applied. The highest Cu accumulation in roots was noted for plants fertilized with 1:10 Ca/Mg ions ratio, together with high Cu translocation to above-ground plant organs, which suggests its higher potential in phytoremediation.

To determine the effects of elevated CO(2) concentration ([CO(2)]) on the temperature-dependent photosynthetic properties, we measured gas exchange and chlorophyll fluorescence at various leaf temperatures (15, 20, 25, 30, 35 and 40°C) in 1-year-old seedlings of the Japanese white birch (Betula platyphylla var. japonica), grown in a phytotron under natural daylight at two [CO(2)] levels (ambient: 400 µmol mol(-1) and elevated: 800 µmol mol(-1)) and limited N availability (90 mg N plant(-1)). Plants grown under elevated [CO(2)] exhibited photosynthetic downregulation, indicated by a decrease in the carboxylation capacity of Rubisco. At temperatures above 30°C, the net photosynthetic rates of elevated-CO(2)-grown plants exceeded those grown under ambient [CO(2)] when compared at their growth [CO(2)]. Electron transport rates were significantly lower in elevated-CO(2)-grown plants than ambient-CO(2)-grown ones at temperatures below 25°C. However, no significant difference was observed in the fraction of excess light energy [(1 - q(P))× F(v)'/F(m)'] between CO(2) treatments across the temperature range. The quantum yield of regulated non-photochemical energy loss was significantly higher in elevated-CO(2)-grown plants than ambient, when compared at their respective growth [CO(2)] below 25°C. These results suggest that elevated-CO(2)-induced downregulation might not exacerbate the temperature-dependent susceptibility to photoinhibition, because reduced energy consumption by electron transport was compensated for by increased thermal energy dissipation at low temperatures.

To assess the effects of elevated CO(2) concentration ([CO(2)]) on the photosynthetic properties around spring budbreak, we monitored the total leaf sugar and starch content, and chlorophyll fluorescence in 1-year-old needles of Sakhalin spruce (Picea glehnii Masters) seedlings in relation to the timing of budbreak, grown in a phytotron under natural daylight at two [CO(2)] levels (ambient: 360 μmol mol(-1) and elevated: 720 μmol mol(-1)). Budbreak was accelerated by elevated [CO(2)] accompanied with earlier temporal declines in the quantum yield of PSII electron transport (Φ(PSII)) and photochemical quenching (q(L)). Plants grown under elevated [CO(2)] showed pre-budbreak leaf starch content twice as high with no significant difference in Φ(PSII) from ambient-CO(2)-grown plants when compared at the same measurement [CO(2)], i.e., 360 or 720 μmol mol(-1), suggesting that the enhanced pre-budbreak leaf starch accumulation might not cause down-regulation of photosynthesis in pre-existing needles under elevated [CO(2)]. Conversely, lower excitation pressure adjusted for the efficiency of PSII photochemistry ((1 - q(P)) F(v)'/F(m)') was observed in plants grown under elevated [CO(2)] around budbreak when compared at their growth [CO(2)] (i.e., comparing (1 - q(P)) F(v)'/F(m)' measured at 720 μmol mol(-1) in elevated-CO(2)-grown plants with that at 360 μmol mol(-1) in ambient-CO(2)-grown plants), which suggests lower rate of photoinactivation of PSII in the elevated-CO(2)-grown plants around spring budbreak. The degree of photoinhibition, as indicated by the overnight-dark-adapted F(v)/F(m), however, showed no difference between CO(2) treatments, thereby suggesting that photoprotection during the daytime or the repair of PSII at night was sufficient to alleviate differences in the rate of photoinactivation.

It was previously shown that nitrogen fertilization immediately after commencement of SD exposure enhanced the floral induction effect of SD in June-bearing strawberries ( Sonsteby et al., 2009 ). In order to optimize the timing of such fertilization under field conditions, seasonal timing of floral initiation in the strawberry cultivars ‘Frida’, ‘Polka’, ‘Korona’ and Florence’ was studied in the field at five contrasting latitudinal and altitudinal geographic locations in Norway and, for comparison, under controlled environment conditions with 12 h photoperiod and temperatures ranging from 9 to 18 °C. Serial collections and dissections of crowns from the various locations revealed that floral initiation was successively delayed with increasing latitude and altitude of the location, and with decreasing temperature under controlled environment conditions. Both in the field and in the phytotron, floral initiation was earliest in ‘Frida’ closely followed by ‘Polka’ and in due course by ‘Korona’ and finally ‘Florence’ which was particularly slow to respond. Floral initiation in the phytotron was progressively advanced with increasing temperature and was optimal at 15–18 °C. Flowering time in the field was mainly determined by thermal relations in the spring and early summer, and accordingly, it was strongly delayed with increasing latitude and altitude of the location. In addition, late floral initiation in autumn also delayed flowering in the spring. Based on these observations, optimal timing of autumn fertilization for the various locations and cultivars are suggested.

SUMMARY Actively-growing, single-stemmed plants of five Scandinavian and British cultivars of black currant (Ribes nigrum L.) were exposed to autumn temperatures of 9o, 12o, 18o, and 24oC in daylight phytotron compartments with natural daylength conditions at As, Norway (59o 40' N) in order to evaluate the effects of elevated autumn temperature on growth cessation and floral initiation in this species. The treatments were started on 11 August and lasted until 13 October (9 weeks) when the plants were moved outdoors for cold-hardening for 7 weeks, then cold-stored at ‐2oC over the Winter. The following Spring, the plants were moved into a heated greenhouse at 15oC with natural daylength conditions and monitored for bud burst and flowering and fruiting performance. Unexpectedly, the cessation of growth in the Autumn was promoted by increasing temperature, and was earliest at 24oC. The high-latitude cultivar, ‘Ojebyn’, and the Norwegian-bred ‘Kristin’ were the most temperature-responsive cultivars, while the Norwegian cultivar, ‘Narve Viking’ was least influenced by Autumn temperature. Leaf senescence and abscission, which followed in due course, were also promoted by high Autumn temperature in ‘Ojebyn’, but by low Autumn temperature in all other cultivars. Bud burst in the following Spring was consistently delayed by a few days by high Autumn temperature, while flowering was earliest in plants from intermediate temperatures. Furthermore, the magnitude of flowering was increased several-fold by elevated Autumn temperature, usually reaching an optimum at 18oC. Again, this enhancement effect was least in ‘Narve Viking’, in which the extent of flowering was also significantly reduced when autumn temperatures increase from 18oC to 24oC. It is concluded that elevated Autumn temperature, as a consequence of global warming, does not represent a threat to the normal cessation of growth or floral initiation in black currant.

This paper reports the complete process from secondary emblings (SE-derived plants) regeneration to acclimatization of Eucalyptus globulus and describes histocytological changes that occur in leaves from in vitro to ex vitro acclimatization for a 3-month period. After elongation, plants were transferred to pots with sterilized peat:perlite and acclimatized in a phytotron, with progressive reduction of RH and increase of light intensity. Histocytological analyses were performed in fixed material using light microscopy and ultrastructural changes followed by electron microscopy (SEM and TEM). The protocol used allowed the successful acclimatization of the emblings. Plants looked morphologically normal and FCM screening revealed no ploidy or DNA content abnormalities. Histocytological analyses showed significant changes along time, mostly in stomata shape and aperture, starch reserves, chloroplast morphology and mesophyll differentiation. This is the first report concerning emblings acclimatization to ex vitro conditions in Eucalyptus. It was clearly demonstrated that during acclimatization emblings suffered profound changes in leaf morphology in order to successfully adapt to ex vitro conditions.

Pyxidanthera brevifolia is an evergreen semi-woody cushion plant endemic to the Sandhills of North and South Carolina, with the majority of populations occurring on Fort Bragg Military Reservation in North Carolina. Currently the species is listed as Endangered in North Carolina and is designated as a Species at Risk (SAR) by the US Department of Defense. Previous studies have suggested that seeds may not be viable because they failed to germinate under controlled conditions. Our objectives in this study were to attempt germination of Pyxidanthera brevifolia seeds, determine the best temperature conditions for germination, and understand more about germination requirements to aid in future restoration efforts. Using seeds that had been stored at room temperature for six months, we performed a germination experiment at the NCSU Phytotron with six treatments, all combinations of three temperature regimes (low (18 °C day / 14 °C night), medium (22/18 °C), and high (26/22 °C)) and two light condition...

光強度（0～2,000 μmol・m−2・s−1）と温度（15～35℃）に着目し，ファイトトロン内で測定したハイブッシュ種‘Weymouth’とラビットアイ種‘Tifblue’の光合成特性を比較した．両品種の個葉の光合成速度は，温度が高いほど大きくなった．低温条件（15～20℃）における個葉の光合成速度は‘Weymouth’が‘Tifblue’に比べて大きかった．一方，高温条件（25～35℃）におけるそれは品種間で相違がなかったが，‘Weymouth’は‘Tifblue’に比べて蒸散速度が大きく，水利用効率が小さかった．また，ハイブッシュ種‘Blueray’を用い，高温条件で行った実験でも同様の結果が得られた．これらの特性は，ハイブッシュ種が冷涼な気候に適していること，ラビットアイ種が高温，乾燥条件に対する耐性を持つことに関係していると考えられた．また，35℃の高温および1,000 μmol・m−2・s−1以上の光強度の条件で測定した水利用効率の大小は，耐暑性がある個体の選抜の一指標となると考えられた．強光，高温条件では蒸散速度が大きくなるため，夏季の高温時には水分の損失を防ぐために光飽和に達する光強度である1,000 μmol・m−2・s−1を目安に遮光を行うことが有効であることが示唆された．

In this study we investigated the interaction between temperature and genotype on fruit development and levels of total phenols and anthocyanins in cloudberry. The experiment was done in a phytotron using one female ('Fjellgull') and one hermaphroditic ('Nyby') cultivar. Plants were grown at 9, 12, 15 and 18 ◦ C in 24-h photoperiod. The female cultivars were pollinated with pollen from a male ('Apollen') clone and from the hermaphrodite clone. Parthenocarpic fruit development was induced by gibberellic acid (GA3). Ripe berries were frozen individually at −80 ◦ C and stored until analyses. There was a linear, double logarithmic relationship between temperature and number of days from pollination/GA3-treatment to ripening. 'Fjellgull' had significantly larger berries than 'Nyby', and the largest berries were obtained at 12 and 9 ◦ C. Pollen clone did not have a significant effect on berry size. GA3 induced parthenogenesis in 'Fjellgull' and partial parthenogenesis in 'Nyby'. In 'Fjellgull', the parthenocarpic berries were comparable to pollinated ones at low temperatures, but at 18 ◦ C their development was restricted. The level of total anthocyanins was significantly higher in 'Fjellgull' than in 'Nyby', and these levels were significantly enhanced at 9 and 12 ◦ C compared to higher temperatures. Levels of total phenolic compounds were not significantly affected. In conclusion

We report on a substantial reduction of nitrate concentration in leafy vegetables that were subjected to short-term preharvest treatment by narrow-bandwidth red light of high photosynthetic photon flux density generated by a solid-state illuminator. Lettuce (Lactuca sativa cv. Grand rapids), marjoram (Majorana hortensis, Moench.), and green onions (Allium cepa, L. cv. Lietuvos didieji) were grown to harvest time within a greenhouse under daylight with supplementary lighting provided by standard high-pressure sodium lamps (130 μmol·m−2·s−1). A subsequent 3-day treatment within a phytotron under 638-nm light-emitting diodes (500 μmol·m−2·s−1) resulted in the reduction of nitrate concentration by 44% to 65%. The reduction of nitrates was accompanied by an increased concentration of nutritionally valuable carbohydrates, which is also in line with stimulation of expression of nitrate reductase by photosynthetic metabolites. Another indicator of nutritional quality, the content of vitamin C, exhibited some variation that was not directly correlated with the nitrate reduction rate that may be attributed to carbohydrate content variation and leaf tissue aging.

Formation of contractile roots (CRs) in geophyte plants ensures the depth regulation in the soil of the new geophytic organs. The effect of auxin naphthalene acetic acid (NAA) on the development and activity of CRs was studied in Gladiolus grandiflorus cv. ‘Eurovision’ cormel plants. The following parameters were recorded up to 80-90 days from planting following application of 0.054-1.37 mM NAA to leaves of cormels grown in the phytotron under long day conditions (16 h) at 27/17 °C day/night temperature: production of CRs primordia, root elongation and contraction, leaf morphology, corm production, and downward movement in the soil. NAA treatments increased CRs' primordia formation, but delayed the elongation and contraction processes (onset and rate). The typical sequential formation of CRs in gladiolus cormel plants was not observed in NAA-treated cormels, in which simultaneous CR production was observed. NAA inhibited thickening and downward movement of the daughter-corm in the soil and reduced leaf nu...