Plant Growth Chamber Research Articles

Testing the accuracy of new paleoatmospheric CO2 proxies based on plant stable carbon isotopic composition and stomatal traits in a range of simulated paleoatmospheric O2:CO2 ratios

A drive to improve long-term estimates of atmospheric CO 2 change through Earths history has led to the development of novel paleoproxy CO 2 methods applicable to fossil plants. This paper compares two of these paleoproxy CO 2 methods (1) the empirical model of Schubert and Jahren (2012, 2015) termed the C3 plant proxy, which was developed using the hyperbolic relationship observed between plant carbon isotope discrimination (Δ 13 C) and p CO 2 and (2) the mechanistic model of Franks et al. (2014), which utilizes stomatal anatomy measurements and plant carbon isotopic composition and is based on established equations for leaf gas exchange and photosynthesis. To date both models lack detailed experimental testing of the robustness and accuracy of their p CO 2 predictions in relation to phylogenetic differences in Δ 13 C between C3 plant groups and/or species and atmospheric O 2 concentration, which has co-fluctuated with CO 2 in the geological past. Here, we investigate if these novel paleoproxy CO 2 approaches can produce phylogenetically independent estimates of p CO 2 that are not influenced by variations in atmospheric oxygen. To address this, model estimates of p CO 2 were compared with measured CO 2 values for ten plant species representing four major vascular plant groups (lycophytes, monilophytes, gymnosperms and angiosperms) grown for 6 months in walk-in plant growth chambers under varying O 2 :CO 2 ratios. Results from the mechanistic model reveal that species-specific plant responses to atmospheric CO 2 accounted for the large variability in CO 2 predictions between species and overestimations of p CO 2 by ∼+232 ppm to 940 ppm. Adjustments to the model that involved: (1) corrections to the photorespiratory compensation point (to account for fluctuating oxygen) and (2) removal of the phylogenetic effect on Δ 13 C, reduced between-species variability (by 50%) and led to better p CO 2 estimates within 58–229 ppm of measured values. The C3 plant proxy (empirical approach) produced accurate CO 2 estimates within +37 to +71 ppm of measured values, however it was affected by species-specific differences in Δ 13 C and for some species resulted in negative estimates of p CO 2 . Sub-ambient O 2 (16%) resulted in erroneously high CO 2 estimates (∼100 ppm higher than the control) for a number of species, as plant responses to decreasing O 2 mimicked those of increasing CO 2 . We conclude that both models (with phylogenetic corrections to Franks et al. (2014)) can produce accurate estimates of paleo-CO 2 when a mix of three to four species, preferably containing representatives from both pteridophytes and spermatophytes, is used to obtain a consensus p CO 2 estimate. We advocate a fossil assemblage rather than a single-species approach to paleo-CO 2 estimation in future application of either method.

Cryopreservation of grapevine (Vitis spp.) shoot tips from growth chamber-sourced plants and histological observations

Many genebanks rely on cryopreservation as a method to preserve vulnerable field collections of vegetatively propagated crops. Effective cryopreservation procedures have been identified for Vitis; however, they usually use in vitro plantlets as the shoot tip source materials. It is costly to establish Vitis collections in vitro prior to cryopreservation. We sought to determine if growth chamber derived Vitis plants could serve as the source of shoot tips for cryopreservation. Nodal sections from growth chamber derived plants were surface-disinfected and placed in tissue culture on pre-treatment medium for 2 weeks. Uniform apical shoot tips (1 mm) were first obtained from the nodal sections and then precultured for 3 days on medium containing 0.3 M sucrose, salicylic acid, glutathione (reduced form), ascorbic acid and plant preservative mixture. Half-strength PVS2 was applied for 30 min at 22 °C, prior to full-strength PVS2 treatment at 0 °C. Cryopreserved shoot tips had the highest average regrowth of 50 and 55 % without and with cold-acclimation followed with a full-strength PVS2 exposure duration of 40 and 30 min at 0 °C, respectively. This cryopreservation protocol achieved high percentages of regrowth in V. vinifera 'Chardonnay' and 'Riesling' and V. hybrid 'Oppenheim'. Histological observations revealed that shoot tips from growth chamber plants had apical as well as multiple lateral meristems that survived LN immersion. The preservation of multiple meristems in each shoot tip may increase the capacity of shoot tip regeneration in cryopreserved Vitis that originates from ex vitro sources. The high percentage of regrowth after shoot tip cryopreservation using Vitis shoot tips derived from growth chamber source plants suggest that it may be possible to cryopreserve Vitis shoot tips without first introducing each accession into tissue culture.

Investigation of Seed transmission in Peronospora belbahrii the Causal Agent of Basil Downy Mildew

Downy mildew in sweet basil (Ocimum basilicum L.) caused by the oomycete pathogen Peronospora belbahrii Thines was first recorded in Israel in 2011. Within one year, the pathogen has spread all over the country, causing devastating economic damage to basil crops. Similar outbreaks were reported in Europe, the USA, and Asia. Seed transmission and seedling trade were suggested as possible explanations for this rapid spread. Here, we show that P. belbahrii can develop systemically in artificially inoculated basil plants in growth chambers. It may reach remote un-inoculated parts of the plant including the axillary buds but not the roots or seeds. To verify whether transmission of the disease occurs via seeds, we harvested seeds from severely infected, field-grown basil plants. Harvests were done in four seasons, from several basil cultivars growing in three locations in Israel. Microscopic examinations revealed external contamination with sporangia of P. belbahrii of untreated seeds, but not of surface-sterilized seeds. Pathogen-specific PCR assays confirmed the occurrence of the pathogen in untreated seeds, but not in surface-sterilized seeds. Contaminated seeds were grown (without disinfection) in pasteurized soil in growth chambers until the four–six leaf stage. None of several thousand plants showed any symptom or sporulation of downy mildew. PCR assays conducted with several hundred plants grown from contaminated seeds proved no latent infection in plants developed from such seeds. The results confirmed that (i) P. belbahrii can spread systemically in basil plants, but does not reach their roots or seeds; (ii) sporangia of P. belbahrii may contaminate the surface, but not the internal parts, of seeds produced by infected basil plants in the field: and (iii) contaminated seeds produce healthy plants, which carry no latent infection. The data suggest that P. belbahrii in Israel is seed-borne, but not seed-transmitted.

Silicon-mediated role of 24-epibrassinolide in wheat under high-temperature stress.

High temperature poses a severe extortion to productivity of many crops like wheat. Therefore, well documented roles of brassinosteroid (BR) and silicon (Si) in terms of abiotic stress tolerance, the current study was designed to evaluate the response of wheat (Triticum aestivum L. Var. PBW-343) to 24-epibrassinolide (EBL) mediated by silicon grown under high temperature stress. At 10- and 12-day stage after sowing, the seedlings were administered Si (0.8mM) through the sand, and the plants at 20, 22, or 24days after sowing (DAS) were given EBL (0.01μM) through foliage. Plants were treated to high-temperature stress (35/28 or 40/35°C), for 24h with 12-h photoperiod in plant growth chamber at 25- and 26-day stage of growth. High temperatures cause significant reduction in growth performance and photosynthesis-related attributes at 35days after sowing. However, antioxidant enzymes and proline content also augmented substantially with increasing temperature. BR and Si enhanced antioxidant activity and proline content, which was earlier increased by the high temperature. It is established that interaction of EBL and Si considerably improved the growth features, photosynthetic efficacy, and several biochemical traits under high-temperature stressthrough elevated antioxidant system and osmoprotectant.

Model-based phenology prediction of Helicoverpa armigera (Hübner) (Noctuidae: Lepidoptera) on tomato crop

Helicoverpa armigera (Hubner) is a destructive polyphagous insect pest of worldwide importance. In Indian subcontinent and Southern Europe, the pest causes serious damage to tomato crop. High migrating ability of H. armigera is expected to threaten more area cultivated under this crop. It is therefore important to understand the development of this pest on tomato to predict its phenology well in advance in order to manage it efficiently. Keeping that in view, the development and mortality of immature stages of H. armigera were studied inside plant growth chamber with six different alternating temperatures (Max/Min °C) viz. 25:10, 25:13, 25:16, 30:10, 30:13, and 30:16 °C with 14:10 h photoperiod. Development of all immature stages quickened with increasing alternating temperatures. Tomato-fed larval stage suffered heavy mortality which ranged from 69 to 85% and completed development in 47.4–31.6 days with rising alternating temperatures. The development data of H. armigera immature stages were fitted into various models like simple linear model, Ikemoto–Takai model and Kontodimas nonlinear model. Among linear models, Ikemoto–Takai model estimated lower threshold temperatures of egg, larva, and pupa viz. 9.9, 7.8, and 12.3 °C, respectively. Daily mean temperatures falling below these threshold values likely to be fatal for immature stages of H. armigera. Degree-day estimates were 37.4, 508.4, and 154.6°D for egg, larva, and pupa, respectively. Both linear models were close enough in predicting immature stage duration of H. armigera. The Kontodimas nonlinear model also predicted 32.5 and 37.8 °C as maximum threshold temperature for egg and larva, respectively. The predicted fatal temperatures for immature stages of H. armigera through various models in this study will help to take timely and need-based control measures.

Flower forcing possibilities in Hemerocallis hybrids

Daylilies (Hemerocallis hybrids) are one of the most important ornamental perennial plants nowadays used in gardens and parks. Flower forcing of daylily hybrids in early spring or autumn could broaden their application and marketing possibilities. There is very limited data available on this topic. In our early flower forcing experiment ‘Moonlit Masquerade’, for late flowering ‘Mary Todd’ were used. During the study we have sought answer for the following questions: the amount of growing degree-day required for flower stalk induction and for flowering and whether the day length has an effect on these values or not. In the early flower forcing experiment 4 treatment groups were established: plants of the first treatment group were placed in a moderately heated greenhouse without assimilation lighting. The second treatment group were placed in the same greenhouse but artificial light was used to extend the day length for 15 h. The examination of the third group happened in a plant growth chamber with 15 h day length and a daily average temperature of 20°C was provided for the plants, and there was also a control group in open field environment. For late flowering the bare rooted dormant plants were stored in refrigerator and were planted to open-field in late spring and summer. During the experiments temperature data were logged and plant morphology characteristics were measured in two following year. According to the results it can be stated that the differentiation of inflorescence is not depending on the day length rather on the leaf surface area. Growing degree-day is the main factor which influences the speed of inflorescence development once it has already differentiated, so temperature is the key factor in flower bud opening and it also defines the number of the developing flower buds. The data from late flowering experiment show that bare-rooted daylily plants are suitable for long-term cold storage and this method offers late season flower forcing.

Forced Flowering in Mandarin Trees under Phytotron Conditions.

Phytotron has been widely used to assess the effect of numerous parameters on the development of many species. However, less information is available on how to achieve fast profuse flowering in young fruit trees with this plant growth chamber. This study aimed to outline the design and performance of a fast clear methodology to force flowering in young mandarin trees (cv. Nova and cv. Clemenules) and to analyze the influence of induction intensity on inflorescence type. The combination of a short water stress period with simulated spring conditions (day 13 h, 22 °C, night 11 h, 12 °C) in the phytotron allowed flowers to be obtained only after 68-72 days from the time the experiment began. Low-temperature requirements were adequately replaced with water stress. Floral response was proportional to water stress (measured as the number of fallen leaves): the greater the induction, the larger the quantity of flowers. Floral induction intensity also influenced inflorescence type and dates for flowering. Details on artificial lighting (lumens), photoperiod, temperatures, plant size and age, induction strategy and days for each stage are provided. Obtaining flowers from fruit trees at any time, and also several times a year, can have many advantages for researchers. With the methodology proposed herein, three, or even four, flowering periods can be forced each year, and researchers should be able to decide when, and they will know, the duration of the entire process. The methodology can be useful for: flower production and in vitro pollen germination assays; experiments with pests that affect early fruit development stages; studies on fruit physiological alterations. All this can help plant breeders to shorten times to obtain male and female gametes to perform forced-crosses.

First Report of Clonostachys rhizophaga as a Pathogen of Water Chestnut (Eleocharis dulcis) in Anhui Province of China

HomePlant DiseaseVol. 103, No. 1First Report of Clonostachys rhizophaga as a Pathogen of Water Chestnut (Eleocharis dulcis) in Anhui Province of China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Clonostachys rhizophaga as a Pathogen of Water Chestnut (Eleocharis dulcis) in Anhui Province of ChinaX. Yang, A.-F. Zhang, C.-Y. Gu, H.-Y. Zang, and Y. ChenX. YangSearch for more papers by this author, A.-F. ZhangSearch for more papers by this author, C.-Y. GuSearch for more papers by this author, H.-Y. ZangSearch for more papers by this author, and Y. Chen†Corresponding author: Y. Chen; E-mail: E-mail Address: chenyu66891@sina.comhttp://orcid.org/0000-0001-9767-5255Search for more papers by this authorAffiliationsAuthors and Affiliations X. Yang A.-F. Zhang C.-Y. Gu H.-Y. Zang Y. Chen † , Institute of Plant Protection and Agro-products Safety, Anhui Academy of Agricultural Sciences, Hefei 230031, China; Scientific Observing and Experimental Station of Crop Pests in Hefei, Ministry of Agriculture, China; Laboratory of Quality & Safety Risk Assessment for Agro-Products, Hefei, Ministry of Agriculture, China; and Key Laboratory of Anhui Agricultural Sciences (18S1103), Hefei 230031, China. Published Online:26 Oct 2018https://doi.org/10.1094/PDIS-05-18-0840-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Water chestnut, Eleocharis dulcis (Burm. f.) Trin., is a sedge native to China and is widely grown in the world, especially in the tropical and subtropical regions. In September 2017, black spots were observed on about 80% of the water chestnuts in several villages of Wuwei County, Anhui Province. The diseased water chestnuts showed longitudinal chlorosis streaks with black spots on the stem surface and internal vascular necrosis. To isolate the pathogen, the diseased stem segments (2 mm in length) were surface sterilized with 1% NaClO for 1min, rinsed twice for 30 s with sterile deionized water, and then incubated on water agar medium at 25°C in a growth chamber for 3 days. Then a mycelial plug was transferred to potato dextrose agar (PDA) medium and incubated for 2 weeks in the growth chamber at 25°C. Representative isolates formed off-white mycelia, dimorphic, Verticillium-like (primary) or penicillate (secondary) conidiophores, and ovoidal to elongated, slightly curved or asymmetrical, hyaline conidia about 5 to 8.8 μm long and 2.5 to 3.9 μm wide (more than 50 conidia were measured),with laterally displaced hilum. To identify the eight isolates, partial fragments of internal transcribed spacer (ITS) and β-tubulin (tub2) gene were amplified according to the method of Abang et al. (2009). A 525-bp ITS fragment (GenBank accession no. MG872331) was amplified from the ITS for all eight isolates with universal primers ITS1/ITS4, showing 100% similarity to the Clonostachys rhizophaga strain CML2312 (GenBank accession no. KC806275) and CML2310 (GenBank accession no. KC806272). A 592-bp fragment of tub2 (GenBank accession no. MH325937) was amplified with the primers bt2a (5′-AACATGCGTGAGATTGTAAGT-3′) and bt2b (5′-TCTGGATGTTGTTGGGAATCC-3′) and showed 100% similarity to the C. rhizophaga strain 1019 (GenBank accession no. FJ593883). To verify the pathogenicity of these isolates, a 5-mm-diameter mycelial plug was cut from 2-week-old colonies grown on PDA for each of the isolates and inoculated on the punctured stem of healthy water chestnuts. The inoculation site was covered with wet cotton and wrapped with Parafilm. The control plants were treated by the same method but using sterile PDA plugs of the same size. All the treatments were incubated in a plant growth chamber at 25°C with a 12-h photoperiod. Two weeks after inoculation, symptoms on all inoculated stems were identical to those described above with a dark area surrounded by a yellow halo on the stem surface and internal browning, whereas the control plants did not show any symptoms. Furthermore, the fungus was reisolated from all the inoculated stems and identified to be C. rhizophaga as described above, fulfilling Koch’s postulates. This pathogen has been reported to infect other plants, such as chickpea (Abang et al. 2009), giant bamboo (Dendrocalamus giganteus) (Zazzerini and Quaglia 2010), and Canary lsland pine (Pinus canariensis) (Piontelli and Giusiano 2003); however, to our knowledge, this is the first report of C. rhizophaga infecting water chestnut plants in China. This disease is an emerging problem in Anhui Province, and it is necessary to develop new disease management practices to sustain commercial production in this region.

Bacillus subtilis ameliorates water stress tolerance in maize and common bean

ABSTRACT Water stress is one important abiotic stress with negative impacts on plant productivity. In order to ameliorate abiotic stress, plant growth-promoting rhizobacteria (PGPR), such as Bacillus subtilis, can be used due to their positive effects on plant physiology. The present study aimed to evaluate the effects of B. subtilis on the performance of maize and common bean under water deficit conditions. The study was performed in a plant growth chamber and the growth, gas exchange parameters and antioxidant activity were evaluated. B. subtilis promoted the growth of common bean and maize, and also increased the water use efficiency. The inoculation with B. subtilis increased leaf water content and the regulation of stomata, without damaging photosynthetic rates. Overall, B. subtilis decreased antioxidant activities in both plants. The results suggest that B. subtilis could be used as inoculants for common bean and maize to protect against water stress.

Characterization of the infection process by Peronospora belbahrii on basil by scanning electron microscopy

Basil downy mildew caused by Peronospora belbahrii is a disease of sweet basil (Ocimum basilicum) production worldwide. In this study, sweet basil was grown in plant growth chambers and inoculated with sporangia of P. belbahrii harvested from previously infected plants. Plants were placed in closed, clear plastic bags and leaves harvested over time and observed using scanning electron microscopy. In most cases, sporangia germinated myceliogenically on abaxial and adaxial leaf surfaces as early as three days after inoculation. Germ tubes and the tips of hyphae ramifying on leaf surfaces directly penetrated basil leaves to initiate the infection process. Hyphal growth was not observed to gain entrance to the interior of leaves through stomata, though growth over these openings was observed. Most frequently, seven days after inoculation, one or more sporangiophores grew through stomata to produce new sporangia on both the abaxial and adaxial surfaces of leaves. Macroscopic signs of infection were visible on both sides of leaves approximately ten days after inoculation under the conditions of this study. These results contribute to a better understanding of the infection process and disease onset of P. belbahrii and should help in the development of more effective measures for reducing basil downy mildew.

Micropropagation of Mespilus germanica L.

The data presented in this paper is supporting the research article “Variable seed behavior increases recruitment success of a hardwood tree, Zelkova serrata, in spatially heterogeneous forest environments” (Oyama et al., 2018) [1]. We provided the data of several ecological properties of the two types of the seeds (i.e. shoot seeds vs. single seeds) with distinctly different dispersal behaviors. We provide data of terminal velocity, which was measured by releasing 50 replicates of each seed type from a height of 5.0 m in dead air space in a gymnasium. We also show the data of germination cue [i.e. red:far-red (R:FR) ratios], which was examined in plant growth chambers that received three distinct R:FR ratios (0.1, 0.4, and 1.0; 16 h photoperiod) or no illumination. Further, we show the data of the rates of multi-locus outcrossing rates and biparental inbreeding in each of single- and shoot seeds. The mating system parameters were estimated by assaying a total of 80 shoot seeds and 70 single seeds that were randomly collected from Parent 1 and Parent 2 for five microsatellite loci. Finally, we show the data of hemispherical canopy photographs, which were taken at different distance from the adults using a digital camera equipped with a fisheye lens.

Photosynthetic apparatus plays a central role in photosensitive physiological acclimations affecting spinach (Spinacia oleracea L.) growth in response to blue and red photon flux ratios

Relative abundance of blue (B) and red (R) photons in the incident light plays a major role in regulating the morphology and physiology of plants. Many studies have been carried out to determine the R:B photon flux ratio (PFR) required for eliciting desired traits in various plant species. However, studies investigating the impact of R:B PFR on the underlying metabolic events and their mutual interactions are limited. In the present study, spinach (Spinacia oleracea L. cv. All Green) plants were raised in a plant growth chamber under R:B PFRs of 100R:0B, 75R:25B, 50R:50B, 25R:75B and 0R:100B provided by customized light-emitting diode (LED) panels. Data related to plant growth, status of photosynthetic apparatus, nitrogen metabolism, metabolite profile, oxidative stress and antioxidant defense response were collected. A putative mechanistic concept highlighting the interplay between photosynthesis, C- and N-assimilation and oxidative stress response in regulating plant growth under changing R:B PFR has been presented. Steady growth under B and R combined treatments was associated with high chlorophyll content, PSII quantum yield (Fv/Fm, Fv/Fo, ΦPSII) and vitality index (RFd) along with proper C- and N-assimilation. Reduction in non-photochemical quenching (NPQ) and oxidative stress was also observed under 25R:75B to 75R:25B light treatments. Subdued photosynthetic activity under deficiency of B waveband resulted in arrested growth due to suboptimal C- and N-assimilation. Monochromatic B lighting caused damage to the photosynthetic apparatus due to increased photooxidation. Presence of B photons was favorable for eliciting enzymatic and non-enzymatic antioxidant defense responses. However, the antioxidant machinery was unable to ameliorate the excessive oxidative damage under 0R:100B treatment resulting in suboptimal plant growth. Integrity and proper functionality of the photosynthetic apparatus under B and R combined light quality treatments was found to play a pivotal role in coordinating the non-photosynthetic light-sensitive metabolic processes in response to changing R:B PFR for ensuring proper plant growth.

UV-B strengthens antioxidant responses to drought in Nicotiana benthamiana leaves not only as supplementary irradiation but also as pre-treatment

Potentials of UV-B (280–315 nm) radiation to alleviate effects of water deficit were studied using Nicotiana benthamiana plants in growth chambers. 10-days of limited watering resulted in 40% loss of soil water content as compared to well-watered controls. This drought was applied in three different ways: (i) in itself, (ii) after 4-days exposure of 6.9 kJ m−2 d−1 biologically effective supplementary UV-B radiation as pre-treatment, or (iii) in parallel with 6.9 kJ m−2 d−1 biologically effective supplementary UV-B. Responses were examined in two leaf groups: fully developed mature leaves (ML) and young leaves emerging during the 10-day treatment (YL). ML responded to UV-B or drought as single factor treatments with 7–14% loss of photochemical yield, while YL photochemistry was not decreased under the same conditions. The parallel two-factor treatment had no aggravating effect but alleviated drought-induced loss of leaf photochemistry in ML. Several positive single factor effects of drought or UV-B on antioxidants remained significant in the two-factor treatment both in ML and YL. Effects of the two factors applied in parallel were additive (equal to the sum of the effects caused by single factors separately) on total antioxidant capacities and singlet oxygen neutralizing; and synergistic (larger than the sum of single factor effects) on the flavonoid index in ML. A sequential application of UV-B and drought had additive positive effects on antioxidant capacity and flavonoid index of ML suggesting lasting effects of UV-B pre-treatment.

Effect of predicted climate change on growth and yield performance of wheat under varied nitrogen and zinc supply

Sustainable crop production is crucial to address global food security and requires a solid input of chemical fertilizers containing macro (e.g. nitrogen: N) and micro (e.g. zinc: Zn) nutrients. However, climatic factors beyond farmers’ management capabilities determine the final crop yields, and world’s climate has been changing more rapidly than ever due to human activities such as industrialization and deforestation. This study evaluates the interactive effects of predicted climate change and N and Zn supply on performance of bread wheat as a model staple food crop. Bread wheat (T. aestivum cv. Ceyhan-99) was cultivated in soil fertilized with adequate or low N and Zn in pots under ambient climate (ambient CO2 and temperature) or predicted climate (700 μmol mol−1 CO2 and 3 °C temperature rise) conditions in dedicated plant growth chambers. Plants were harvested at full maturity and grain yield, and yield attributes along with Zn and N status of grains were determined. Predicted climate (PC) treatment significantly accelerated plant growth rate resulting in early onset of successive growth stages and maturity. In both PC and ambient climate (AC) conditions, adequate supply of N and Zn significantly increased straw and grain yield by increasing number of spikes per plant and number of grains per spike, whereas PC significantly reduced straw and grain yield through reducing number of spikes per plant, particularly in plants supplied with adequate N. Effect of adequate Zn or PC treatments were significant only under adequate N supply. Adequate N not only increased grain protein concentration but also grain Zn, particularly under adequate Zn application. In general, PC tended to increase grain Zn concentration, but the effect was non-significant. PC had no effect on grain protein concentration, whereas it significantly reduced grain protein yield (i.e. total mass of protein in whole grains of a single plant). The future climate with elevated CO2 and raised temperature can dramatically reduce duration of time to complete successive growth stages in wheat. Plants cultured under PC conditions had significantly lower straw and grain yield, although supplied with ample fertilization. Whereas the PC and adequate Zn treatments enhanced main spike gain yield and number of grains per spike, PC declined overall grain yield, particularly due to severe reduction in number of spikes per plant. We conclude that sustaining a higher number of spikes per plant along with adequate nutrition with N and Zn are key factors to benefit from an elevated CO2 atmosphere and to minimize adverse effects of rising temperatures on wheat yield and quality.

Enemy of my enemy: evidence for variable soil biota feedbacks of Vincetoxicum rossicum on native plants

Interactions between plants and soil biota can be major drivers of plant invasions. The ‘Enemy of my enemy’ hypothesis (EEH) predicts that native plants are more negatively impacted by enemies (e.g. pathogens) that accumulate and spillover from the invader’s rhizosphere than the invaders themselves, thereby facilitating the invasion. We tested EEH using Vincetoxicum rossicum, one of the most invasive plant species in Eastern North America, and a total of eight co-occuring native plant species. Specifically, we predicted that the native species would grow less in presence of soil biota associated with V. rossicum than that from uninvaded soils. Field soils were collected from four V. rossicum invaded and neighboring uninvaded areas for use in two experiments. In Experiment 1, V. rossicum and each of five native plant species were grown in a plant growth chamber for 3 months, either in presence or absence of soil biota from the invaded and uninvaded soils. We found that only one species (Solidago canadensis) supported EEH. In contrast, the legume Desmodium canadense more than doubled its biomass in response to V. rossicum -associated soil biota. In Experiment 2, four native legume species, including D. canadense, were examined for EEH in the same manner as in Experiment 1. Only one species (Lespedeza hirta) supported EEH and, again, V. rossicum-associated soil biota was advantageous to D. canadense. In summary, we found inconsistent support for the EEH between V. rossicum and native co-occurring species in Eastern North America. We conclude that the accumulation of rhizosphere enemies in native plants may not be a major factor in the invasive success of V. rossicum.

Testing the AC/DC hypothesis: Rock and roll is noise pollution and weakens a trophic cascade.

Anthropogenic sound is increasingly considered a major environmental issue, but its effects are relatively unstudied. Organisms may be directly affected by anthropogenic sound in many ways, including interference with their ability to detect mates, predators, or food, and disturbances that directly affect one organism may in turn have indirect effects on others. Thus, to fully appreciate the net effect of anthropogenic sound, it may be important to consider both direct and indirect effects. We report here on a series of experiments to test the hypothesis that anthropogenic sound can generate cascading indirect effects within a community. We used a study system of lady beetles, soybean aphids, and soybean plants, which are a useful model for studying the direct and indirect effects of global change on food webs. For sound treatments, we used several types of music, as well as a mix of urban sounds (e.g., sirens, vehicles, and construction equipment), each at volumes comparable to a busy city street or farm tractor. In 18‐hr feeding trials, rock music and urban sounds caused lady beetles to consume fewer aphids, but other types of music had no effect even at the same volume. We then tested the effect of rock music on the strength of trophic cascades in a 2‐week experiment in plant growth chambers. When exposed to music by AC/DC, who articulated the null hypothesis that “rock and roll ain't noise pollution” in a song of the same name, lady beetles were less effective predators, resulting in higher aphid density and reduced final plant biomass relative to control (no music) treatments. While it is unclear what characteristics of sound generate these effects, our results reject the AC/DC hypothesis and demonstrate that altered interspecific interactions can transmit the indirect effects of anthropogenic noise through a community.

Razmnožavanje paulovnije korijenskim reznicama

U rod Paulownia, porodica Paulowniaceae, ubraja se od devet vrsta i nekoliko prirodnih hibrida koji od prirode rastu u Kini. Važne vrste u ovom rodu su: P. albiflora, P. australis, P. catalpifolia, P. elongata, P. fargesii, P. fortunei, P. kawakamii i P. tomentosa. U novije vrijeme hibridizacijom su dobiveni brojni hibridi s ciljem povećanja brzine rasta i prirasta te otpornosti na niske temperature. U Hrvatskoj se najčešće razmnožavaju hibridi paulovnije Shan Tong i 9501 iako postoje i drugi dobiveni vlastitim selekcijama. Cilj ovoga članka je objasniti načine razmnožavanja paulovnije u prirodi i problematiku njezine invazivnosti te razmnožavanje u rasadniku pomoću autovegetativne metode makropropagacije korjenovim reznicama. Postoje tri faze zakorjenjivanja reznica: inicijacija, indukcija i ekspresija. Postoji direktna i indirektna indukcija. Najosjetljiviji trenutak je povezivanje provodnih elemenata korjenčića i dijela stanice. Uspješnost pojave korjenčića na reznici ovisi o: fiziološkom stanju matične biljke, količini šećera, metabolizmu auxina, mineralnoj ishrani, metabolizmu fenola i dr. Postoje četiri faze razmnožavanja paulovnije iz korijenskih reznica: uzimanje i dorada korijenskih reznica s matične biljke u matičnjaku, pikiranje reznica u pvc lončiće ispunjene supstratom za zakorjenjivanje, zakorjenjivanje korjenskih reznica i osnivanje novog matičnjaka. Korijenske reznice paulovnije Shang Tong i 9501 uzimane su s obzirom na polaritet na način da se donji (distalni) dio korijena rezao pod kutom od 45 stupnjeva a gornji (proksimalni) pod kutom od 90 stupnjeva. Reznice su podijeljene su na kratke (8 cm) i dugačke (15 cm). Svaka skupina reznica dodatno je podijeljena na tanke i debele na način da razlika bude na oko vidljiva. Iz svake skupine u istraživanje je uzeto po 15 reznica. Napravljen je pokus na način da jedan dio reznica bude pikiran u grijanom stakleniku 7 dana od vađenja korijena a drugi dio nakon sušenja na sobnoj temperaturi u komori rasta. Prva skupina od 60 reznica uzeta je 14. prosinca i pikirana u perforirane pvc vrećice volumena 5,0 l i u gotovi supstrat za zakorjenjivanje Klasman Steckmedium. U supstrat za zakorijenjivanje dodano je 3g/l gnojiva s produženim djelovanjem treće generacije Osomocote Exact Standard 5-6M formulacije 15-9-12+2MgO+TE. Reznice nisu tretirane fitohormonom niti fungicidima protiv truleži. Pikiranje reznica je obavljeno na način da je gornja površina reza od 90 stupnjeva bila u razini supstrata. Duga skupina od 60 reznica stavljena je na sušenje u komoru rasta Kambič RK-980 CH. Temperatura u komori iznosila je 21 °C i relativna vlaga zraka od 40 % što predstavlja čuvanje reznica u konstantnim sobnim uvjetima. Reznice su čuvane u komori rasta 5 dana. Pikiranje je obavljeno na isti način kao i u slučaju prve skupine reznica 21.12.2017. godine. Prvo registriranje zakorjenjivanja obavljeno je 19.02.2018. godine što znači za prvu skupinu 67 dana od pikiranja a za drugu skupinu 60 dana od pikiranja. Sušenje reznica hibrida paulovnije Shan Tong dovelo do povećanja zakorjenjivanja u svim varijantama, a posebno je izraženo kod debelih reznica duljine 8 cm i debelih reznica duljine 15 cm. Može se preporučiti uzimanje debljih reznica i njihovo sušenje na sobnoj temperaturi u trajanju od 5 dana jer se dobiva značajnije veći postotak zakorjenjivanja. Pretjerana vlaga u supstratu za zakorjenjivanje korijenskim reznicama paulovnije negativno utječe na razvoj korijenskog sustava. Kod hibrida paulovnije 9501 također je utvrđeno kako sušenje reznica dovodi do povećanja zakorjenjivanja u svim varijantama, osim kod tankih reznica duljine 8 cm kod kojih je dobiven isti postotak zakorjenjivanja (33%). Posebno je zanimljiva situacija kod debelih reznica duljine 8 cm kod kojih se bez sušenja nije zakorjenila niti jedna reznica a sa sušenjem čak 80 %. Može se preporučiti uzimanje debljih reznica hibrida paulovnije 9501 i njihovo sušenje na sobnoj temperaturi u trajanju od 5 dana jer se dobiva značajnije veći postotak zakorjenjivanja. Postotak zakorjenjivanja reznica bez sušenja bio bi sigurno veći da su se uzele odmah nakon vađenja korijenskog sustava bagerom što se preporuča u praksi. U ovom slučaju minimalne temperature zraka od -4 °C i -5,6 °C dovele su do smrzavanja korijenskog sustava. Prosječna minimalna temperatura zraka u razdoblju od 8. do 14. prosinca. iznosila je svega 0,8 °C. Kod smrznutog korijena kora se odvaja rukom od drva a takve reznice ili propadaju ili tjeraju iz nižih adventivnih pupova. Korijenske reznice hibrida paulovnije Shan Tong i 9501 trebale bi se uzimati odmah nakon vađenja korijenskog sustava matične biljke a prosječne temperature zraka trebale bi biti iznad 0 °C. U ovim istraživanjima dokazana je štetnost temperatura od -4 °C i -5,6 °C na korijenske reznice jer su one dovele do njihovog smrzavanja. Najbolje kalendarsko vrijeme za vađenje korijenskih reznica, ovisno o godini, bilo bi u mjesecu ožujku. Utvrđena je mogućnost zakorjenjivanja korijenskih reznica hibrida paulovnije 9501 u običnoj vodi u kontroliranim uvjetima (bez svjetla, konstantna temperatura od 20 °C). Reznice su stavljene u „in vitro“ klijalicu Snijders Scientific B.V., ECD01E dana 21.12.2017. a fotografirane 21.02.2018. odnosno 62 dana od stavljanja u vodu.

Plant growth chamber design for subambient pCO2 and δ13 C studies.

Subambient pCO2 has persisted across the major Phanerozoic ice ages, including the entire late Cenozoic (ca 30Ma to present). Stable isotope analysis of plant-derived organic matter is used to infer changes in pCO2 and climate in the geologic past, but a growth chamber that can precisely control environmental conditions, including pCO2 and δ13 C value of CO2 (δ13 CCO2 ) at subambient pCO2 , is lacking. We designed and built five identical chambers specifically for plant growth under stable subambient pCO2 (ca 100 to 400ppm) and δ13 CCO2 conditions. We tested the pCO2 and δ13 CCO2 stability of the chambers both with and without plants, across two 12-hour daytime experiments and two extended 9-day experiments. We also compared the temperature and relative humidity conditions among the chambers. The average δ13 CCO2 value within the five chambers ranged from -18.76 to -19.10‰; the standard deviation never exceeded 0.14‰ across any experiment. This represents better δ13 CCO2 stability than that achieved by all previous chamber designs, including superambient pCO2 chambers. Every pCO2 measurement (n=1225) was within 5% of mean chamber values. The temperature and relative humidity conditions differed by no more than 0.4°C and 1.6%, respectively, across all chambers within each growth experiment. This growth chamber design extends the range of pCO2 conditions for which plants can be grown for δ13 C analysis of their tissues at subambient levels. This new capability allows for careful isolation of environmental effects on plant 13 C discrimination across the entire range of pCO2 experienced by terrestrial land plants.

Evaluation of the Antimicrobial Activity of Endophytic Bacterial Populations From Chinese Traditional Medicinal Plant Licorice and Characterization of the Bioactive Secondary Metabolites Produced by Bacillus atrophaeus Against Verticillium dahliae.

Endophytic bacteria associated with medicinal plants possess unique strategies that enhance growth and suvival of host plants, many of which are mediated by distinctive secondary metabolites. These bacteria and their secondary metabolites are important subjects for both basic and applied research aimed at sustainable agriculture. In the present study, 114 endophytic strains isolated from the wild ethnomedicinal plant Glycyrrhiza uralensis (licorice) were screened for their in vitro antimicrobial activities against common fungal pathogens of tomato (Fusarium oxysporum f. sp., Fulvia fulva, Alternaria solani), cotton (Fusarium oxysporum f. sp. Vesinfectum, Verticillium dahliae), pomegranite (Ceratocystis fimbriata), Cymbidinium (Colletotrichum gloeosporioides), and Tsao-ko (Pestalotiopsis microspora and Fusarium graminearum) and the common bacteria Staphylococcus aureus, Bacillus cereus, Salmonella enteritidis, and Escherichia coli. Several Bacillus strains, particularly Bacillus atrophaeus and Bacillus mojavensis, had a broad spectrum of antifungal and antibacterial activity. A total of 16 strains, selected based on broad antimicrobial activity, were shown to contain at least one putative secondary metabolite-encoding gene (i.e., polyketide synthase or non-ribosomal peptide synthetase) and/or one lytic enzyme (i.e., protease, cellulase, lipase, chitinase), which may be important mediators of antagonistic activity against pathogens. Five strains, representing Bacillus atrophaeus and Bacillus mojavensis, were selected for plant growth chamber experiments based on strong in vitro antifungal activities. All five strains significantly reduced disease severity in Arabidopsis thaliana plants challenged with V. dahlia infection. Gas-chromatography/mass-spectrometry analysis of cell-free extracts of Bacillus atrophaeus strain XEGI50 showed that at least 13 compounds were produced only during co-cultivation with V. dahlia, including putative compounds known to have antimicrobial activity, such as 1,2-benzenedicarboxylic acid, bis (2-methylpropyl) ester; 9,12-octadecadienoic acid (Z,Z)-, methyl ester; 9-octadecenoic acid, methyl ester, (E)-; and decanedioic acid, bis(2-ethylhexyl) ester. To our knowledge, this study is the first to report that bacteria isolated from G. uralensis have biocontrol abilities. Our findings provide new insights into the antimicrobial activities of natural endophytes, particularly B. atrophaeus, and suggest this species may a promising candidate as a biocontrol agent to confer resistance to Verticillium wilt disease and other phytopathogens in cotton and other crops.

Changes in yield attributes and K allocation in wheat as affected by K deficiency and elevated CO2

Elevated carbon dioxide enhances biomass production and final crop yield of C3 species as a consequence of increased photosynthesis, water use efficiency and RuBisCO saturation. However, this enhancement is limited by environmental conditions such as nutrient deficiencies. This study evaluates the interactive effects of K supply (deficient or adequate) and atmospheric CO2 (ambient or elevated) on grain yield and yield related attributes along with allocation of K in different shoot parts (i.e. grains, leaves, stem and peduncle) in bread wheat. Bread wheat (T. aestivum cv. Tahirova) was cultivated in soil fertilized with adequate or deficient K in pots under ambient (420 μmol mol−1) or elevated (700 μmol mol−1) atmospheric CO2 conditions in dedicated plant growth chambers. At full maturity, plants were harvested and grain yield and yield attributes along with K status of grains, peduncle, leaves and stem parts were determined. While K deficiency severely reduced grain yield and yield attributes under both ambient (a-CO2) and elevated (e-CO2) CO2 conditions, e-CO2 significantly enhanced grain yield even in K-deficient plants through maintaining a greater harvest index, spikes per plant and grain weight and thus increased overall K use efficiency. Deficient-K treatment significantly increased grain K concentration as a consequence of “concentration effect”. On the contrary, K concentration in leaf, stem and peduncle was severely decreased whereas e-CO2 had an additive effect on the decrease in K concentrations. Consequently, in deficient-K plants K content (total K accumulated/taken up) in all shoot parts including grains was reduced to only a fraction of adequate-K plants. Moreover, deficient-K plants tended to allocate a greater portion of K in grains as compared to other shoot parts. Elevated CO2 also enhanced K allocation into grains particularly in deficient-K plants. Potassium deficiency severely reduces grain yield and biomass production in bread wheat in both a-CO2 and e-CO2 environments, however e-CO2 partly alleviates the detrimental effect of K deficiency on grain yield, but not straw yield. Plants under K deficiency stress allocated a greater portion of K in the grains and e-CO2 augmented this effect. In wheat, any one of peduncle, leaf or stem K concentration is a better measure of overall plant K nutritional status as compared to grain K, which may be severely biased due to “concentration effect” in K-deficient plants.