Compact Plant Research Articles

Dwarfing Effect of Plant Growth Retarders on Melaleuca alternifolia

Rapid growth and scattered plant types are urgent issues for potted Melaleuca alternifolia. An effective strategy for dwarfing cultivation is the exogenous application of plant growth regulators (PGRs) to plants. However, for many non-wood forest species, there is currently limited understanding of the regulatory mechanism of dwarfing effects of PGRs, which greatly limits the application of PGRs. In this study, three PGRs, paclobutrazol (PP333), uniconazole (S3307), and chlormequat chloride (CCC) were applied to dwarf terpinen-4-ol M. alternifolia. By observing the morphological characteristics and leaf anatomy of M. alternifolia after dwarfing and measuring its photosynthetic characteristics and physiological and biochemical indexes, the dwarfing effect of the three PGRs and the underlying mechanisms were investigated to provide a reference for the cultivation of M. alternifolia by dwarfing. The results show that the PP333 (P3) treatment at 2000 mg·L−1 had the best dwarfing effect on M. alternifolia, with a compact plant shape, thicker stems, and green leaf color. At the same time, it increased the chlorophyll contents, changed the blade structure, increased the content of soluble substances and the activity of antioxidant enzymes, increased the endogenous hormones indole-3-acetic acid (IAA), gibberellin A3 (GA3), and trans-zeatin-riboside (ZR), and decreased abscisic acid (ABA) levels.

Fertilization and Paclobutrazol Application for Sustainable Production and Post-production Performance of Petunia

This study examined the interaction between constant liquid fertilization (CLF) concentrations and plant growth regulator (PGR) application concentrations on petunia (Petunia ×hybrida) growth and flowering in the production and post-production environments. Paclobutrazol application is a common practice in bedding plant production to achieve a compact plant that increases greenhouse space-use efficiency, shipping density, and tolerance to physical handling stresses in the post-production environment. The objective of this research was to determine the best strategy for balancing CLF and PGR application concentration in the greenhouse environment so that growth and flowering can be maximized in the post-production environment. A two-factorial combination of four CLF concentrations [50, 100, 150, or 200 ppm nitrogen (N)] and four paclobutrazol drench concentrations (0, 5, 10, or 20 ppm) were provided to plants during the production phase, and plant growth and flowering were recorded in the production and post-production environments. From a sustainability perspective, the ideal PGR concentration was 5 ppm paclobutrazol, since this concentration resulted in the best combination of production and post-production characteristics and performance. At this PGR concentration, all plant growth and flowering measures increased as CLF increased from 50 to 200 ppm N; however, all CLF concentrations also produced commercially acceptable plants. Therefore, the ideal CLF concentration depends on the size of plant desired; that is, CLF concentrations as low as 50 to 100 ppm N can be provided depending on the market size requirements of the plants being grown. Based on our results, a combination of 50 ppm N CLF with 0 ppm paclobutrazol or 100 ppm N CLF with 5 ppm paclobutrazol both demonstrated adequate growth control during both production and post-production phases.

Effects of fertilizer reduction coupled with straw returning on soil fertility, wheat root endophytic bacteria, and the occurrence of wheat crown rot.

Excessive fertilization is associated with nutrient loss, soil compaction, and weak plant resistance. Straw returning can increase soil fertility with a consequent reduction in fertilizer, but the effects of fertilizer reduction coupled with straw returning on crop endophytic microbes and crop disease are poorly understood. Therefore, using metagenomic sequencing methods we investigated the responses of soil fertility, diversity, the function of root endophytic bacteria, and the occurrence of wheat crown rot due to the application of fertilizer (no, moderate and excessive fertilizer) coupled with or without straw returning after 7 years of treatments. The results showed that, after excessive fertilization, the wheat crown rot became severe, registering a disease index of 23. Compared with excessive fertilization, moderate fertilization coupled with straw returning significantly reduced the incidence of wheat crown rot, the disease index was reduced by 38.50%, and the richness and diversity of endophytic bacteria were increased by 61.20 and 11.93%, respectively, but the soil fertility was not significantly affected. In addition, moderate fertilization coupled with straw returning changed the community structure of endophytic bacteria and increased the relative abundance of carbohydrate metabolism and nitrogen fixation-related genes by 4.72 and 9.32%, respectively. Our results indicated that fertilizer reduction coupled with straw returning reduced the occurrence of wheat crown rot, increased the diversity of endophytic bacteria, and changed the community structure and function of endophytic bacteria, which will provide a better understanding of the interaction of fertilization coupled with straw returning, endophytic bacteria and wheat crown rot.

Dysfunction of GmVPS8a causes compact plant architecture in soybean

Vacuolar Protein Sorting 8 (Vps8) protein is a specific subunit of the class C core vacuole/endosome tethering (CORVET) complex that plays a key role in endosomal trafficking in yeast (Saccharomyces cerevisiae). However, its functions remain largely unclear in plant vegetative growth. Here, we identified a soybean (Glycine max) T4219 mutant characterized with compact plant architecture. Map-based cloning targeted to a candidate gene GmVPS8a (Glyma.07g049700) and further found that two nucleotides deletion in the first exon of GmVPS8a causes a premature termination of the encoded protein in the T4219 mutant. Its functions were validated by CRISPR/Cas9-engineered mutation in the GmVPS8a gene that recapitulated the T4219 mutant phenotypes. Furthermore, NbVPS8a-silenced tobacco (Nicotiana benthamiana) plants exhibited similar phenotypes to the T4219 mutant, suggesting its conserved roles in plant growth. The GmVPS8a is widely expressed in multiple organs and its protein interacts with GmAra6a and GmRab5a. Combined analysis of transcriptomic and proteomic data revealed that dysfunction of GmVPS8a mainly affects pathways on auxin signal transduction, sugar transport and metabolism, and lipid metabolism. Collectively, our work reveals the function of GmVPS8a in plant architecture, which may extend a new way for genetic improvement of ideal plant-architecture breeding in soybean and other crops.

Use of MAXFEA-ANSYS tool to study the Electro-Magnetic behaviour of the new ST40 inner vacuum chamber proposal during a plasma VDE

Tokamak Energy Ltd. is developing compact fusion power plants based on two promising technologies, Spherical Tokamaks (STs) and High Temperature Superconductors (HTS), with the aim to build a first demonstrative plant by the 2030′s. On its path to fusion power, Tokamak Energy is presently operating ST40, a new generation ST that is currently the highest field device of its kind. In the near future, an important ST40 upgrade is planned and foresees the manufacturing and the installation of a new vacuum chamber, called IVC2. This upgrade will allow the exploitation of ST40 to its maximum performances enabling Double Null (DN) diverted operations with up to 2 MA of plasma current and 3 T of toroidal field. IVC2 is currently in the final design stage. The necessity to analyse in detail the Electro-Magnetic (EM) behaviour of this component under the loads coming from plasma disruptions has recently emerged in order to verify the design or drive further modifications. In this context, a study to analyse the EM response of IVC2 during a plasma Vertical Displacement Event (VDE) has been carried out using the MAXFEA code in combination with ANSYS APDL, following a recent workflow development. The main output of this study is the evaluation of the transient EM force density in IVC2 and other components for subsequent mechanical assessments. The aim of this paper is to present the results of this analysis to show the successful application of this procedure in the context of ST40 project.

The effect of in situ irradiation on the superconducting performance of REBa2Cu3O7−δ-coated conductors

Commercial fusion power plants will require strong magnetic fields that can only be achieved using state-of-the-art high-temperature superconductors in the form of REBa2Cu3O7−δ-coated conductors. In operation in a fusion machine, the magnet windings will be exposed to fast neutrons that are known to adversely affect the superconducting properties of REBa2Cu3O7−δ compounds. However, very little is known about how these materials will perform when they are irradiated at cryogenic temperatures. Here, we use a bespoke in situ test rig to show that helium ion irradiation produces a similar degradation in properties regardless of temperature, but room-temperature annealing leads to substantial recovery in the properties of cold-irradiated samples. We also report the first attempt at measuring the superconducting properties while the ion beam is incident on the sample, showing that the current that the superconductor can sustain is reduced by a factor of three when the beam is on.Impact statementREBa2Cu3O7−δ high-temperature superconductors are an enabling technology for plasma confinement magnets in compact commercial fusion power plants, owing to their ability to carry very high current densities when processed as quasi-single crystals in the form of coated conductors. In service in a fusion device, the magnet windings will be exposed to a flux of fast neutrons that will induce structural damage that will adversely affect the superconducting performance, but very little data are currently available on the effect of irradiation at the cryogenic temperatures relevant for superconducting magnets. Moreover, even room-temperature annealing substantially affects superconducting properties after irradiation, so to obtain key technical data for fusion magnet designers, it is important to measure these properties in situ, under irradiation. This work shows that for the first time, it is important to consider how energetic particles directly influence superconductivity during irradiation because we observe a reduction in zero-resistance current by a factor of as much as three when an ion beam is incident on the sample. Although neutrons will not interact with the material in the same way as charged ions, primary knock-on ions from neutron damage are expected to have a similar effect to the He+ ions used in our study.Graphical abstract

Efeito do regulador de crescimento paclobutrazol no ajuste do tamanho do manjericão como planta de vaso

Abstract Basil (Ocimum basilicum L., Lamiaceae) is an herbal species cultivated primarily for culinary and aromatherapy. Basil plant height could reach more than 60 cm, and the plants tend to elongate, particularly in low-light environments. Our current study examined the potential uses of plant growth retardant paclobutrazol to control sweet basil height and improve potted basil’s ornamental quality. The treatment tested was paclobutrazol concentration at 0, 5, 10, and 20 ppm, applied as 100 mL media drenching per pot five weeks after planting. The control plants were water-drenched using the same volume at the same time. Basil treated with PBZ at 10 ppm or 20 ppm had significantly shorter, smaller shoot canopy diameter, node and leaf number than the control, but had a similar number of branches to the control. Basil treated with PBZ at 10 ppm or 20 ppm showed a more compact and bushy pot plants with the height to pot ratio of 1.5. Higher leaf chlorophyll, indicated by a higher index value, was recorded only with the PBZ concentration of 20 ppm compared to the control and the other PBZ concentrations. Basil growth responses to PBZ at 10 ppm were not significantly different from those treated with PBZ at 20 ppm, therefore the use of PBZ at a lower concentration (10 ppm) is preferable. Further studies should examine whether repeated PBZ applications at lower concentration is more effective in producing shorter and more compact pot plants.

Uso de paclobutrazol e etileno na produção envasada de abacaxizeiro ornamental

Abstract The expansion of residential areas has increased the demand for exotic and increasingly compact landscape plants. In this context, this work aimed to evaluate the effects of paclobutrazol (PBZ) and the timing of ethylene application on growth reduction and flowering anticipation in ornamental pineapples grown in pots. The randomized block design was used with factorial arrangement (2 x 5) and 4 replications and 4 plants per plot. The primary treatments are the presence and absence of PBZ. The secondary treatments were five times of floral induction with ethylene: 90; 120; 150; 180; 210 days after transplanting (DAT) the seedlings into the pots. It was evaluated the variables: height ratio between the heights of the pot and the plant; rosette diameter; leaves length ‘D’ and flowering index. At 255 DAT, although the plants did not respond to floral induction with ethylene, only those treated with PBZ were more compact and had different characteristics such as smaller size and a ratio below 1/3 of the height of the vase in relation to the plant that to favor its commercialization, in pot.

An LTR retrotransposon insertion inside CsERECTA for an LRR receptor-like serine/threonine-protein kinase results in compact (cp) plant architecture in cucumber.

The compact (cp) phenotype in cucumber (Cucumis sativus L.) is an important plant architecture-related trait with a great potential for cucumber improvement. In this study, we conducted map-based cloning of the cp locus, identified and functionally characterized the candidate gene. Comparative microscopic analysis suggested that the short internode in the cp mutant is due to fewer cell numbers. Fine genetic mapping delimited cp into an 8.8-kb region on chromosome 4 harboring only one gene, CsERECTA (CsER) that encodes a leucine-rich repeat receptor-like kinase. A 5.5-kb insertion of a long terminal repeat retrotransposon in the 22nd exon resulted in loss-of-function of CsER in the cp plant. Spatiotemporal expression analysis in cucumber and CsER promoter-driven GUS assays in Arabidopsis indicated that CsER was highly expressed in the stem apical meristem and young organs, but the expression level was similar in the wild type and mutant cucumber plants. However, CsER protein accumulation was reduced in the mutant as revealed by western hybridization. The mutation in cp also did not seem to affect self-association of CsER for formation of dimers. Ectopic expression of CsER in Arabidopsis was able to rescue the plant height of the loss-of-function AtERECTA mutant, whereas the compact inflorescence and small rosette leaves of the mutant could be partially recovered. Transcriptome profiling in the mutant and wild type cucumber plants revealed hormone biosynthesis/signaling, and photosynthesis pathways associated with CsER-dependent regulatory network. Our work provides new insights for the use of cp in cucumber breeding.

Turbidity removal and pH of raw water treated with natural coagulants

Concerns regarding water pollution and scarcity have led researchers to investigate new sustainable water treatment technologies, such as the use of natural coagulants, that can be used for water treatment in decentralized locations at small rural communities, as these materials can be used in compact water treatment plants. Thus, the present study evaluated the use of natural coagulants, drumstick tree seeds and tannins extracted from black acacia, in water treatment to remove turbidity. To determine the ideal coagulant dosage, jar tests were performed, followed by filtration to remove the formed sludge. pH and turbidity were analyzed to compare the coagulants efficiency. The natural coagulants achieved satisfactory removal of suspended solids, completely removed turbidity, and causing no significant changes in pH, unlike aluminum sulfate, hence, these natural materials can be used as an alternative to chemical coagulants.

Chemical and Phytoplankton profile of two water plants model before and after treatment in Menoufia governorate, Egypt

Safe drinking water is ahealth necessity. This study was for comparing between certain physico-chemical and microbial parameters of two water treatment plants (Shebin El-kom conventional plant and Shobrabass compact plant) during a period from February 2019 to December 2019. The treated water at these plants had a remarkable enhancement as compared with raw one basically with the values of TDS, conductivity, total alkalinity, phosphates and nitrates but treated water of Shobrabass has high turbidity ranged from 1.6 NTU to 3 NTU compared with Shebin El- kom that ranged from 0.18 NTU to 0.33 NTU. Regarding to biotic component, it was proved that both total and fecal coliform beside algae disappeared more or less completely at the end of the treatment process. The results showed diverse phytoplankton structures of three groups namely: Bacillariophyta, Chlorophyta and Cyanophycta. Bacillariophyta represented the most widespread group in Shebin El- kom and Shobrabass raw water during the period of study as it accounted 72.6 % and72.7%, respectively of total annual crop, followed by chlorophyta with 17.4% and 15.5%, respectively and Cyanophyta ranked as 3rd group with 11.6% and 11.5% of total annual crop for Shebin El-kom raw water and Shobrabass raw water, respectively. The conventional Shebin El-kom plant was more effective than Shobrabas compact plant to obtain better potable water and so a modification was performed on Shobrabas. The final results of turbidity decreased from 2.3 NTU to 1.4 NTU and the total algal count decreased from (1000× 10³ organisms/ L) to (26× 10³ organisms/ L).

Um novo cultivar de Dendrobium: Den ‘Aurora’s Orange Hana’

Abstract Dendrobium is a large genus of orchids containing more than 1800 species spliced in some sections and many are very attractive such as the group Nobile from section Dendrobium. They are an easy-to-cultivate ornamental group with pseudobulbs cane-like, mostly hard, erect, covered by the bases of the leaves and flowering in almost all internodes. In this work, we tried to develop a cultivar of small size with floriferous plants. The hybrid Dendrobium Aurora’s Orange Hana was produced and showed compact and floriferous plants with varied colours among the offspring. Three superior clones were selected due to a better display, architecture, three to four flowers per node, and vibrant colours. This new cultivar can be easily grown in pots or on living supports, forming compact and very flowering clumps.

МЕТОДИКА ВЫБОРА ПАРАМЕТРОВ ПАССИВНОГО ФИЛЬТРА ДЛЯ ПОВЫШЕНИЯ КАЧЕСТВА ЭЛЕКТРОЭНЕРГИИ В ЭЛЕКТРИЧЕСКИХ СЕТЯХ С АКТИВНЫМИ ВЫПРЯМИТЕЛЯМИ

The relevance Due to the wide spread of compact metallurgical plants, which use powerful drives with frequency converters with active rectifiers (FC-AR), an urgent task has become the fight against resonant phenomena in medium voltage electrical networks, since these converters, despite their significant advantages, have a disadvantage — the deterioration of the quality of electricity in the power supply system 6–35 kV. Existing methods of dealing with resonant phenomena in medium voltage electrical networks, in which non-linear elements are present, such as powerful drives of rolling mills with FC-AR used in power supply systems of metallurgical enterprises, do not always allow changing the situation for the better. One way to solve this problem is to use classic traditional filters. Often, the use of traditional filters to eliminate strong voltage distortions in sections of 6–35 kV does not have the desired effect. The installation of traditional filters is accompanied by additional parasitic current resonances, which amplify the intermediate harmonics. These harmonics multiply the oscillations and strongly distort the voltage shape when the frequency response of the distribution network is superimposed with the region of high-frequency harmonics generated by modern FC-AR. Aim of research The article is devoted to the issues of improving the electromagnetic compatibility (EMC) of FC-AR as part of electric drives of rolling mill stands with an internal power supply system for metallurgical plants in the presence of resonant phenomena through the use of specialized passive filters (SPF). Research methods Methods of theoretical and experimental researches are applied in the work. When studying the causes of the occurrence of resonant phenomena, experimental data obtained in the course of research work at the metallurgical plant JSC Metallurgical Plant Balakovo were used. For the processing of experimental data, mathematical modeling methods were used in the Matlab environment with the Simulink application. Results The significance of the results of the work lies in improving the quality of electricity in the distribution electrical networks of mini-plants with FC-AR in the presence of resonant phenomena in the frequency response of the network through the use of SPF. The implementation of the results of the work is an improvement in quality indicators and, as a result, an increase in the reliability of the operation of all power converters in the internal power supply system and a decrease in emergency situations associated with the failure of power elements. The results of the work were implemented at the metallurgical plant of JSC Metallurgical Plant Balakovo. The quantitative indicator of the technical effect of changing the level of the coefficient of the total harmonic components of the voltage in the general sections of the factory GPP КU is: 1) without the use of SPF КU = 10.26 %; 2) when using SPF КU = 1.42 % (relative change δ КU = –72 %). These results can be used at other compact metallurgical enterprises with extended cable lines of medium voltage 6–35 kV and powerful electric drives with FC-AR.

Catalytically active membranes for esterification: A review

Esterification is an important process in the food industry and can be carried out via homogeneous or heterogeneous catalysis. The homogeneous catalyst, despite providing high conversion, can cause corrosion in reactors, which is not observed with the use of heterogeneous catalysts. However, some of these catalysts require a high process temperature and may lose their catalytic activity with reuse. Thus, catalytic membranes have been proposed as a promising alternative. The combination of catalysis and separation in a single module provides greater conversion, reduction of excess reagents, compact industrial plant, making the process more efficient. Within this context, this work aims to present a literature review on the catalytic membrane for the synthesis of esters, improving the understanding of the production and development. This review examines the materials, catalysts used, and synthetic pathways. A comparison between the methods, as well as limitations and gaps in the literature, are highlighted.

Ideal type 1 is caused by a point mutation in the α-tubulin gene that affects microtubule arrangement in soybean

Plant architecture is a target of crop improvement. The soybean mutant ideal type 1 (it1) displays a pleiotropic phenotype characterized by compact plant architecture, reduced plant height, shortened petioles, wrinkled leaves, and indented seeds. Genetic analysis revealed that the pleiotropic phenotype was controlled by an incomplete dominant gene. We characterized the cellular phenotypes of it1 and positionally cloned the it1 locus. Detailed morphogenetic analysis of the it1 mutant revealed an excess of xylem cells and expanded phloem, and polygonal pavement cells. Positional cloning showed that the phenotype was caused by a G-to-A mutation in the second exon of the α-tubulin gene (Glyma.05G157300). The mutation altered microtubule arrangement in pavement cells, changing their morphology. Overexpression of Gmit1 resulted in an it1-like phenotype and polygonal pavement cells and microtubules of overexpressors were parallel or slightly inclined. Five suppressor mutants able to suppress the phenotype of it1 were obtained by EMS mutagenesis in the it1 background. All these mutants carried an additional mutation in the it1 gene. These results suggest that the pleiotropic phenotype of it1 is caused by the mutation in the α-tubulin gene.

Compact plants enhance productivity.

Compact plants enhance productivity.

Impact of Blue Light on Plant Growth, Flowering and Accumulation of Medicinal Flavones in Scutellaria baicalensis and S. lateriflora

Scutellaria baicalensis Georgi (Baikal skullcap) and S. lateriflora (American skullcap) are two ethnobotanical medicinal plants used to treat gastrointestinal, respiratory, and inflammatory disorders, in addition to demonstrated anti-cancer properties. The predominant bioactive compounds produced in these species are unique 4′-deoxyflavones, in roots of S. baicalensis and leaves of S. lateriflora, making these two species suitable to study the effects of light quality on flavone accumulation in aerial and underground tissues. Light emitting diodes were used to study the impact of blue-dominated spectrum on the accumulation of bioactive flavones. Eight major flavones, including 4′-deoxyflavones baicalein, wogonin, baicalin, wogonoside and chrysin, along with 4′-hydroxyflavones scutellarein, scutellarin and apigenin, were quantified using HPLC in high flavone accumulating tissues. Aerial tissues directly exposed to blue light in S. lateriflora showed an increase in the concentrations of scutellarein by 18.7%, scutellarin by 296%, and baicalin by 31.6%. While the roots in S. baicalensis also had significant increases in baicalein by 154% and wogonin by 76% in response to blue light, there was a slight reduction in their respective glycosides baicalin and wogonoside as well as a decrease in total flavone content. Blue light resulted in compact skullcap plants with early flowering and modified flavone profiles.

Performance analyzes of a compact pico hydropower plant with a wide operating range

<span>This paper analyzes the performance of a pico hydropower plant consisting of an axial hydro turbine integrated with a permanent magnet generator (PMG) and connected to a power converter. The proposed system is aimed to obtain a wide system operation range to gain more power captured while maintaining time-harmonic distortion in voltage (THDv) that meets the standard. The PMG specification is 1 kW, 1 phase, 235 V, 50 Hz, 83 rpm. The design and simulation of PMG were carried out by analytical and numerical calculations using FEMM 4.2. The power converter was simulated using PSIM and functions to reduce the THDv and pass the generator voltage between 50–500 V. The results show the THDv of the generating system at the upper and lower limits of the passed voltage having a THDv below 5%. Meanwhile, the PMG performance characteristics at various currents and rotations produce efficiency of 87.20% at nominal current. From these results, it can be concluded that the pico hydropower plant works well as desired.</span>

Photosynthetic Daily Light Integral Influences Growth, Morphology, Physiology, and Quality of Swordfern Cultivars

Boston and Australian swordferns (Nephrolepis sp.) are popular tropical ferns for hanging baskets and containers; however, greenhouse production occurs during times of the year when growers may need to deploy shade or supplemental lighting to manage the growing environment. Our objectives were to quantify the impact of the daily light integral (DLI) on growth, morphology, physiology, and ornamental quality of containerized Nephrolepis species and cultivars, and to establish optimal DLIs for containerized swordferns to assist commercial greenhouse growers with light management strategies during production. Eleven cultivars of Boston swordfern [N. exaltata (L.) Schott Blue Bells, Compacta, Fluffy Ruffles, Gold, Montana, Nevada, Petticoat, Pom Pom, Super, Tiger, and True] and one cultivar of Australian swordfern [N. obliterata (R. Br.) J. Sm. Western Queen] were investigated. Plants were grown for 58 days at 20 °C and placed under one of four different fixed-woven shadecloths providing ≈86%, 62%, 42%, or 26% shade or no shade, thereby establishing mean DLIs of 3.2, 6.4, 10.7, 12.4, and 17.1 mol⋅m−2⋅d−1, respectively. For most cultivars, the growth index, which is an integrated measurement of height and diameter, decreased linearly as the DLI increased from 3.2 to 17.2 mol⋅m−2⋅d−1, resulting in smaller compact plants. Increasing the DLI significantly affected the frond number of each cultivar differently, whereas dry mass generally increased as the DLI increased from 3.2 to 10.7 to 12.4 mol⋅m−2⋅d−1 for most cultivars. For each cultivar, as the DLI increased from 3.2 to 17.1 mol⋅m−2⋅d−1, the chlorophyll concentration index decreased, whereas the hue angle increased and chroma was unaffected. Our results indicate that growers should maintain ≈10 to 12 mol⋅m−2⋅d−1 during greenhouse Nephrolepis production; however, DLIs ≥5.5 mol⋅m−2⋅d−1 and ≤16.5 mol⋅m−2⋅d−1 also improved the quality of some Nephrolepis cultivars.

Growth regulation by air stream-based mechanical stimulation in tomato (Solanum lycopersicum L.) – Part II: Phenotypic and physiological responses

Plant responses to mechanical stimulation have a great potential for growth control of ornamentals plants and vegetable seedlings and is a major requirement to ensure plant compactness and stability. 21 days old tomato (Solanum lycopersicum cv. ‘Romello’) plants were exposed to regularly applied mechanical stimuli for 14 days by applying of a defined air stream through a custom-built air stream applicator. Air stream application gradually reduced total plant leaf area by 14% and promoted radial growth relative to internode length compared to the untreated control, resulting in a more compact and stable plant phenotype, which was also related to an increased stem dry matter content of the air stream-treated plants. The reduction in total plant leaf area was compensated for the translocation of proportionally more assimilates to light-harvesting tissues and to stems at the expense of dry mass accumulation in petioles. Total stem, leaf and root dry mass of air stream-treated plants were unaffected. The specific leaf area of the air stream treated plants was reduced compared to the control, resulting in an increased relative leaf greenness and consequently in an 8% higher net carbon assimilation rates on average compared to the control. Thereby, air stream-treated plants were able to maintain overall biomass accumulation at the same level as the control. Leaf transpiration rate of air stream treated plants was not markedly affected in the long-term. The technique presented should be easily transferable to other plants, such as ornamentals where the application of chemical plant growth regulators is still the most common technique for plant growth control.