An exploratory method to determine the plant characteristics affecting the final yield of Echium amoenum Fisch. & C.A. Mey. under fertilizers application and plant densities.

Employing of advanced statistical methods to quantify agricultural information has helped to carry out targeted planning to alleviate the problems of farmers, researchers and policy section. One of these exploratory methods, is multivariate statistical analysis that examines and models the relationship between variables. Considering the importance of Echium amoenum and its use growing trend in traditional medicine and the pharmaceutical industry, also the lack of information on the correlations between its yield and morpho physiological traits, the objective of this study was to determine the causality path in which the Echium amoenum characteristics affects the yield of Echium amoenum as regards of application of organic and chemical fertilizers under different plant densities. The employed method revealed that organic fertilizers increased flower yield compared with the control. The flower yield as a result of application of compost, vermicompost and cattle manure were increased by 25, 28, and 27% compared with the control, respectively. The results of multiple regression showed that variables of plant height, shoot dry weight, flower number per plant were the main factors affected the flower yield. The relative contribution of shoot dry weight was 16 and 25% more than plant height and flower number per plant, respectively. Causality analysis identified that shoot dry weight per plant had indirect effect on flower yield in different paths, as mainly was imposed through plant height considering the path coefficients. This study suggests that optimum production of Echium amoenum with application of ecological inputs along with effective agronomical managements of the causal paths of flower yield forming, including increase in shoot yield and plant height could be achieved through an ecological cropping system with reduced costs and no health concerning due to agrochemicals residual.

Short-term changes related to autotetraploidy in essential oil composition of Eucalyptus benthamii Maiden & Cambage and its applications in different bioassays.

Some forest trees have been polyploidized to improve their traits and to supply new germplasms for breeding programs. As trees have a long juvenile stage, the early characterization of the chromosome set doubling effects is crucial for previous selection. Thus, we aimed to characterize the chemical variability of essential oils from diploid and autotetraploid germplasms (autotetraploid A and B) of Eucalyptus benthamii, as well as to evaluate their larvicidal and allelopathic effects. Autotetraploid A showed a higher essential oil yield than diploid and autotetraploid B, which did not differ quantitatively. Aromadendrene, viridiflorol and α-pinene were the major compounds in the diploid essential oil. In contrast, compounds were present in autotetraploids, such as 1,8-cineole, limonene, α-terpineol, and α-terpinyl-acetate. Essential oils from the diploid at 50-200 ppm were twice as larvicidal than those from autotetraploids against Aedes aegypti larvae. Considering the phytotoxicity bioassays using Lactuca sativa, essential oils from both ploidy levels affected root growth. Moreover, the essential oils inhibited shoot growth at all concentrations tested (187.5; 375; 750; 1500; and 3000 ppm). Autotetraploid A and B had the same effect on shoot growth as glyphosate. The essential oils had no cytogenotoxic effect on root meristematic cells of L. sativa, whereas phytotoxic potential was identified mainly in shoot growth. This work demonstrated a dramatic change in secondary metabolism (terpene composition) related to an increase in the ploidy level in Eucalyptus germplasms. In addition, we report the novelty of the chemical composition of essential oils among germplasms and their potential use as larvicidal and post-emergence weed control agents.

Screening the Key Region of Sunlight Regulating the Flavonoid Profiles of Young Shoots in Tea Plants (Camellia sinensis L.) Based on a Field Experiment.

Both UV and blue light have been reported to regulate the biosynthesis of flavonoids in tea plants; however, the respective contributions of the corresponding regions of sunlight are unclear. Additionally, different tea cultivars may respond differently to altered light conditions. We investigated the responses of different cultivars ('Longjing 43', 'Zhongming 192', 'Wanghai 1', 'Jingning 1' and 'Zhonghuang 2') to the shade treatments (black and colored nets) regarding the biosynthesis of flavonoids. For all cultivars, flavonol glycosides showed higher sensitivity to light conditions compared with catechins. The levels of total flavonol glycosides in the young shoots of different tea cultivars decreased with the shade percentages of polyethylene nets increasing from 70% to 95%. Myricetin glycosides and quercetin glycosides were more sensitive to light conditions than kaempferol glycosides. The principal component analysis (PCA) result indicated that shade treatment greatly impacted the profiles of flavonoids in different tea samples based on the cultivar characteristics. UV is the crucial region of sunlight enhancing flavonol glycoside biosynthesis in tea shoots, which is also slight impacted by light quality according to the results of the weighted correlation network analysis (WGCNA). This study clarified the contributions of different wavelength regions of sunlight in a field experiment, providing a potential direction for slightly bitter and astringent tea cultivar breeding and instructive guidance for practical field production of premium teas based on light regimes.

A novel adenylate isopentenyltransferase 5 regulates shoot branching via the ATTTA motif in Camellia sinensis.

BACKGROUND: Shoot branching is one of the important agronomic traits affecting yields and quality of tea plant (Camellia sinensis). Cytokinins (CTKs) play critical roles in regulating shoot branching. However, whether and how differently alternative splicing (AS) variant of CTKs-related genes can influence shoot branching of tea plant is still not fully elucidated. RESULTS: In this study, five AS variants of CTK biosynthetic gene adenylate isopentenyltransferase (CsA-IPT5) with different 3' untranslated region (3' UTR) and 5' UTR from tea plant were cloned and investigated for their regulatory effects. Transient expression assays showed that there were significant negative correlations between CsA-IPT5 protein expression, mRNA expression of CsA-IPT5 AS variants and the number of ATTTA motifs, respectively. Shoot branching processes induced by exogenous 6-BA or pruning were studied, where CsA-IPT5 was demonstrated to regulate protein synthesis of CsA-IPT5, as well as the biosynthesis of trans-zeatin (tZ)- and isopentenyladenine (iP)-CTKs, through transcriptionally changing ratios of its five AS variants in these processes. Furthermore, the 3' UTR AS variant 2 (3AS2) might act as the predominant AS transcript. CONCLUSIONS: Together, our results indicate that 3AS2 of the CsA-IPT5 gene is potential in regulating shoot branching of tea plant and provides a gene resource for improving the plant-type of woody plants.

Cytokinin-Based Tissue Cultures for Stable Medicinal Plant Production: Regeneration and Phytochemical Profiling of Salvia bulleyana Shoots.

Salvia bulleyana is a rare Chinese medicinal plant that due to the presence of polyphenols lowers the risk of some chronic diseases especially those related to the cardiovascular system. The present study examines the organogenic competence of various combinations and concentrations of plant growth regulators to develop an efficient protocol for in vitro regeneration of S. bulleyana via leaf explants, maintaining the high production of active constituents. The purpose of the study was also to assess the possibilities of using a cytokinin-based regeneration to effectively produce therapeutic compounds. The adventitious shoot formation was observed through direct organogenesis on media with purine derivatives (meta-topolin, mT and benzylaminopurine, BAP), and through indirect organogenesis on media with urea derivatives (tidiazuron, TDZ and forchlorfenuron, CPPU). The highest regeneration frequency (95%) with 5.2 shoots per explant was obtained on leaves cultured on Murashige and Skoog (MS) medium containing 0.1 mg/L naphthalene-1-acetic acid (NAA) and 2 mg/L BAP. Following inter simple sequence repeat (ISSR) marker-based profiling, the obtained organogenic shoot lines revealed a similar banding pattern to the mother line, with total variability of 4.2-13.7%, indicating high level of genetic stability. The similar genetic profile of the studied lines translated into similar growth parameters. Moreover, HPLC analysis revealed no qualitative differences in the profile of bioactive metabolites; also, the total polyphenol content was similar for different lines, with the exception of the shoots obtained in the presence of CPPU that produced higher level of bioactive compounds. This is the first report of an effective and rapid in vitro organogenesis protocol for S. bulleyana, which can be efficiently employed for obtaining stable cultures rich in bioactive metabolites.

Micropropagation and Secondary Metabolites Content of White-Purple Varieties of Orthosiphon aristatus Blume Miq.

<b>Background and Objective:</b> The cat whiskers plant (<i>Orthosiphon aristatus</i> Blume Miq) is a plant that has been widely used as raw material for traditional medicine. The population of white-purple varieties of <i>O. aristatus</i> is decreasing efforts to maintain the white-purple <i>O. aristatus</i> need to be done keeping in mind its potential as raw material for traditional medicine. This study aims to determine the composition of a suitable medium in growing plantlet <i>O. aristatus</i> white-purple varieties and the content of its secondary metabolites. <b>Materials and Methods:</b> The internode explants were induced on MS medium added by various combinations of zeatin and 2,4-Dichlorophenoxyacetic acid (2,4-D). Root induction was carried out on shoots formed on MS medium with Indole-3-Butyric Acid (IBA). The acclimatization process was carried out using soil media. Determination of secondary metabolite levels was carried out on <i>O. aristatus</i> (<i>in vitro</i> culture) and wild-type plants aged ten months using high-performance liquid chromatography (HPLC). <b>Results:</b> MS+BAP 2ppm+NAA3 ppm media was the optimal medium for growing shoots in leaf explants. Media MS+zeatin 3 ppm+2,4-D 2 ppm produced good shoot growth on internode explants. The best root induction occurred in MS+IBA media of 0.75 ppm. The acclimatization process was successful on shoots originating from the internode, while those from leaf explants had not succeeded in growing and developing. <b>Conclusion:</b> The levels of rosmarinic acid and sinensetin in the white-purple variety <i>O. aristatus</i> (<i>in vitro</i> culture) were 1.08 and 1.62% w/w and higher than those of wild varieties.

Starve to Sustain-An Ancient Syrian Landrace of Sorghum as Tool for Phosphorous Bio-Economy?

Phosphorus (P) is an essential macronutrient, playing a role in developmental and metabolic processes in plants. To understand the local and systemic responses of sorghum to inorganic phosphorus (Pi) starvation and the potential of straw and ash for reutilisation in agriculture, we compared two grain (Razinieh) and sweet (Della) sorghum varieties with respect to their morpho-physiological and molecular responses. We found that Pi starvation increased the elongation of primary roots, the formation of lateral roots, and the accumulation of anthocyanin. In Razinieh, lateral roots were promoted to a higher extent, correlated with a higher expression of SbPht1 phosphate transporters. Infrared spectra of straw from mature plants raised to maturity showed two prominent bands at 1371 and 2337 cm-1, which could be assigned to P-H(H2) stretching vibration in phosphine acid and phosphinothious acid, and their derivates, whose abundance correlated with phosphate uptake of the source plant and genotype (with a higher intensity in Razinieh). The ash generated from these straws stimulated the shoot elongation and root development of the rice seedlings, especially for the material derived from Razinieh raised under Pi starvation. In conclusion, sorghum growing on marginal lands has potential as a bio-economy alternative for mineral phosphorus recycling.

Precursor-Boosted Production of Metabolites in Nasturtium officinale Microshoots Grown in Plantform Bioreactors, and Antioxidant and Antimicrobial Activities of Biomass Extracts.

The study demonstrated the effects of precursor feeding on the production of glucosinolates (GSLs), flavonoids, polyphenols, saccharides, and photosynthetic pigments in Nasturtium officinale microshoot cultures grown in Plantform bioreactors. It also evaluated the antioxidant and antimicrobial activities of extracts. L-phenylalanine (Phe) and L-tryptophan (Trp) as precursors were tested at 0.05, 0.1, 0.5, 1.0, and 3.0 mM. They were added at the beginning (day 0) or on day 10 of the culture. Microshoots were harvested after 20 days. Microshoots treated with 3.0 mM Phe (day 0) had the highest total GSL content (269.20 mg/100 g DW). The qualitative and quantitative profiles of the GSLs (UHPLC-DAD-MS/MS) were influenced by precursor feeding. Phe at 3.0 mM stimulated the best production of 4-methoxyglucobrassicin (149.99 mg/100 g DW) and gluconasturtiin (36.17 mg/100 g DW). Total flavonoids increased to a maximum of 1364.38 mg/100 g DW with 3.0 mM Phe (day 0), and polyphenols to a maximum of 1062.76 mg/100 g DW with 3.0 mM Trp (day 0). The precursors also increased the amounts of p-coumaric and ferulic acids, and rutoside, and generally increased the production of active photosynthetic pigments. Antioxidant potential increased the most with 0.1 mM Phe (day 0) (CUPRAC, FRAP), and with 0.5 mM Trp (day 10) (DPPH). The extracts of microshoots treated with 3.0 mM Phe (day 0) showed the most promising bacteriostatic activity against microaerobic Gram-positive acne strains (MIC 250-500 µg/mL, 20-21 mm inhibition zones). No extract was cytotoxic to normal human fibroblasts over the tested concentration range (up to 250 µg/mL).

Rice amino acid transporter-like 6 (OsATL6) is involved in amino acid homeostasis by modulating the vacuolar storage of glutamine in roots.

Glutamine is a product of ammonium (NH4+ ) assimilation catalyzed by glutamine synthetase (GS) and glutamate synthase (GOGAT). The growth of NH4+ -preferring paddy rice (Oryza sativa L.) depends on root NH4+ assimilation and the subsequent root-to-shoot allocation of glutamine; however, little is known about the mechanism of glutamine storage in roots. Here, using transcriptome and reverse genetics analyses, we show that the rice amino acid transporter-like 6 (OsATL6) protein exports glutamine to the root vacuoles under NH4+ -replete conditions. OsATL6 was expressed, along with OsGS1;2 and OsNADH-GOGAT1, in wild-type (WT) roots fed with sufficient NH4 Cl, and was induced by glutamine treatment. We generated two independent Tos17 retrotransposon insertion mutants showing reduced OsATL6 expression to determine the function of OsATL6. Compared with segregants lacking the Tos17 insertion, the OsATL6 knock-down mutant seedlings exhibited lower root glutamine content but higher glutamine concentration in the xylem sap and greater shoot growth under NH4+ -replete conditions. The transient expression of monomeric red fluorescent protein-fused OsATL6 in onion epidermal cells confirmed the tonoplast localization of OsATL6. When OsATL6 was expressed in Xenopus laevis oocytes, glutamine efflux from the cell into the acidic bath solution increased. Under sufficient NH4+ supply, OsATL6 transiently accumulated in sclerenchyma and pericycle cells, which are located adjacent to the Casparian strip, thus obstructing the apoplastic solute path, and in vascular parenchyma cells of WT roots before the peak accumulation of GS1;2 and NADH-GOGAT1 occurred. These findings suggest that OsATL6 temporarily stores excess glutamine, produced by NH4+ assimilation, in root vacuoles before it can be translocated to the shoot.

Sucrose promotes stem branching through cytokinin.

Shoot branching is an important aspect of plant architecture because it substantially affects plant biology and agricultural performance. Sugars play an important role in the induction of shoot branching in several species, including potato (Solanum tuberosum L.). However, the mechanism by which sugars affect shoot branching remains mostly unknown. In the present study, we addressed this question using sugar-mediated induction of bud outgrowth in potato stems under etiolated conditions. Our results indicate that sucrose feeding to detached stems promotes the accumulation of cytokinin (CK), as well as the expression of vacuolar invertase (VInv), an enzyme that contributes to sugar sink strength. These effects of sucrose were suppressed by CK synthesis and perception inhibitors, while CK supplied to detached stems induced bud outgrowth and VInv activity in the absence of sucrose. CK-induced bud outgrowth was suppressed in vinv mutants, which we generated by genome editing. Altogether, our results identify a branching-promoting module, and suggest that sugar-induced lateral bud outgrowth is in part promoted by the induction of CK-mediated VInv activity.

Co-application of biochar and microorganisms improves soybean performance and remediate cadmium-contaminated soil.

Sole biochar addition or microbial inoculation as a soil amendment helps to reduce cadmium (Cd) toxicity in polluted agricultural soils. Yet the synergistic effects of microorganisms and biochar application on Cd absorption and plant productivity remain unclear. Therefore, a pot experiment was conducted to investigate the combined effect of microorganisms (Trichoderma harzianum L. and Bacillus subtilis L.), biochar (maize straw, cow manure, and poultry manure), and Cd (0, 10, and 30 ppm) on plant physiology and growth to test how biochar influences microbial growth and plant nutrient uptake, and how biochar ameliorates under Cd-stressed soil. Results showed that in comparison to non-Cd polluted soil, the highest reduction in chlorophyll content, photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency, and intercellular CO2 were observed in Cd2 (30 ppm), which were 9.34%, 22.95%, 40.45%, 29.07%, 20.67%, and 22.55% respectively less than the control Cd0 (0 ppm). Among sole inoculation of microorganisms, highest stomatal conductance, water use efficiency, and intercellular CO2 were recorded with combined inoculation of both microorganisms (M3), which were 5.92%, 7.65%, and 7.28% respectively higher than the control, and reduced the Cd concentration in soil, root, and shoot by 21.34%, 28.36%, and 20.95%, respectively, compared to the control. Similarly, co-application of microorganisms and biochar ameliorated the adverse effect of Cd in soybean as well as significantly improved plant biomass, photosynthetic activity, nutrient contents, and antioxidant enzyme activities, and minimized the production of reactive oxygen species and Cd content in plants. Soil amended with poultry manure biochar had significantly improved the soil organic carbon, total nitrogen, total phosphorous, and available potassium by 43.53%, 36.97%, 22.28%, and 4.24%, respectively, and decreased the concentration of Cd in plant root and shoot by 34.68% and 47.96%, respectively, compared to the control. These findings indicate that the combined use of microorganisms and biochar as an amendment have important synergistic effects not only on the absorption of nutrients but also on the reduction of soybean Cd intake, and improve plant physiology of soybean cultivated in Cd-polluted soils as compared to sole application of microorganisms or biochar.

Effect of Growth Regulators on In Vitro Micropropagation of Potato (Solanum tuberosum L.) Gudiene and Belete Varieties from Ethiopia.

AIM: Potato (Solanum tuberosum L.) is one of the important crops in Ethiopia which has a crucial role in nutritional security, poverty alleviation, and income generation. The aim of the present investigation is to develop an efficient in vitro propagation protocol for Belete and Gudiene potato varieties by using lateral bud as explants. MATERIALS AND METHODS: Shoot initiation was achieved by inoculating buds on full-strength MS Murashige and Skoog medium (MS) fortified with variable concentrations of BAP and NAA. Basal MS was used as control throughout the experiment. RESULTS: Results of our study showed that best shoot initiation was obtained on MS medium supplemented with 1.5 mg/l BAP + 3.0 mg/l NAA for Gudiene variety, whereas 1.0 mg/l BAP and 2.0 mg/l NAA produced more shoots in Belete variety. The initiated shoots increased two- to three-fold upon subculture on the MS medium fortified with varying concentrations of BAP and Kinetin. The highest numbers of multiple shoots were obtained in the MS medium containing 2.5 mg/l Kinetin. The combined effect of BAP and Kinetin did not produce any additional positive effect for shoot multiplication. Rooting percentage and number of roots/shoot were found best on the MS medium fortified with 1.0 mg/l IBA + 0.5 IAA. CONCLUSIONS: The variety Gudiene was found best for shoot initiation and root formation, while Belete variety proved its superiority for multiple shoot formation. A total number of 82.66% of plantlets were acclimatized under field conditions. This work indicates the practical applicability of plant tissue culture using lateral bud as explants is effective for micropropagation of potato in vitro.

Growth regulation of bermudagrass (Cynodon dactylon) and zoysiagrass (Zoysia japonica) with glyphosate.

Glyphosate can generate positive effects on turfgrass maintenance as a form of growth control by decreasing the expenses associated with mowing. However, there is little information about the effects of this herbicide on turfgrasses. This study aimed to evaluate the response of bermudagrass and zoysiagrass to the herbicide glyphosate as a growth regulator. Two studies were performed in a greenhouse and repeated at different times. The treatments involved application of glyphosate at 10 different rates (0, 5.625, 11.25, 22.5, 45, 90, 180, 360, 720, and 1.440 g ae ha-1) with four replicates. Evaluations of green cover by digital analysis, injury, and plant height were performed at 7, 14, 21, and 28 days after application, and shoot dry matter of clippings was determined for the last evaluation period. Bermudagrass and zoysiagrass presented variedtolerance to glyphosate toxicity. Overall, the digital analysis showed that green content was negatively influenced by the increase in visual injury caused by glyphosate application. Moreover, increasing the glyphosate rate decreased plant height and shoot dry matter in both turfgrasses. Glyphosate application rates up to 45 g ae ha-1 for bermudagrass and 90 g ae ha-1 for zoysiagrass decreased plant growth without affecting the factors analyzed in this study.

High efficient de novo root-to-shoot organogenesis in Citrus jambhiri Lush.: Gene expression, genetic stability and virus indexing.

A protocol for high-frequency direct organogenesis from root explants of Kachai lemon (Citrus jambhiri Lush.) was developed. Full-length roots (~3 cm) were isolated from the in vitro grown seedlings and cultured on Murashige and Skoog basal medium supplemented with Nitsch vitamin (MSN) with different concentrations of cytokinin [6-benzylaminopurine, (BAP)] and gibberellic acid (GA3). The frequency of multiple shoot proliferation was very high, with an average of 34.3 shoots per root explant when inoculated on the MSN medium supplemented with BAP (1.0 mg L-1) and GA3 (1.0 mg L-1). Optimal rooting was induced in the plantlets under half strength MSN medium supplemented with indole-3-acetic acid (IAA, 0.5-1.0 mg L-1). IAA induced better root structure than 1-naphthaleneacetic acid (NAA), which was evident from the scanning electron microscopy (SEM). The expressions of growth regulating factor genes (GRF1 and GRF5) and GA3 signaling genes (GA2OX1 and KO1) were elevated in the regenerants obtained from MSN+BAP (1.0 mg L-1)+GA3 (1.0 mg L-1). The expressions of auxin regulating genes were high in roots obtained in ½ MSN+IAA 1.0 mg L-1. Furthermore, indexing of the regenerants confirmed that there was no amplicons detected for Huanglongbing bacterium and Citrus tristeza virus. Random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) markers detected no polymorphic bands amongst the regenerated plants. This is the first report that describes direct organogenesis from the root explant of Citrus jambhiri Lush. The high-frequency direct regeneration protocol in the present study provides an enormous significance in Citrus organogenesis, its commercial cultivation and genetic conservation.

Modeling of productivity and nutrient extraction by the Vetiver and Tifton 85 grasses grown in horizontal subsurface flow constructed wetlands.

The objective of this study was to evaluate the productivity of shoot dry biomass and the capacity of nitrogen (N), phosphorus (P) and potassium (K) extraction by the Vetiver and Tifton 85 grasses when cultivated in horizontal subsurface flow constructed wetlands (HSSF-CWs) whose porous medium was saturated with solutions containing different nutrient availability. The grass shoots were cut every 30 days to determine the productivity and N, P and K contents in the plant tissue. Models of productivity and the extraction capacity of each nutrient were obtained as a function of the nutrient concentration. Based on the results obtained, it was verified that the productivity of shoot dry biomass and the extractions of N, P and K by the Vetiver grass increased linearly with the nutrient availability of the nutritive solution. In relation to Tifton 85, quadratic models of productivity and N and K extraction were adjusted. The maximum productivity, N, P and K extraction by Vetiver grass were 513.4, 8.2, 1.9 and 10.39 g m-2 month-1, respectively. In relation to Tifton 85 grass, these values were 739.4, 30.8, 3.0 and 15.59 g m-2 month-1 for productivity, N, P and K extraction, respectively.

Comparative Multi-Omics of Tender Shoots from a Novel Evergrowing Tea Cultivar Provide Insight into the Winter Adaptation Mechanism.

Tea (Camellia sinensis [L.] O. Kuntze) tree is a perennial plant in which winter dormancy is an important biological adaptation to environmental changes. We discovered and reported a novel tea tree cultivar that can generate tender shoots in winter several years ago, but the molecular mechanism for this unique phenotype remains unknown . Here, we conducted comparative transcriptomics, proteomics and metabolomics along with phytohormone quantitation between the winter and spring tender shoots to investigate the physiological basis and putative regulatory mechanisms of its evergrowing character during winter. Our multi-omics study has led to the following findings. Gibberellin (GA) levels and key enzymes for GA biosynthesis and the signal transduction pathway were increased in the winter shoots, causing the ABA/GA content ratio to decrease, which might play a key regulatory role in maintaining normal growth during winter. The abundance of proteins, genes and metabolites involved in energy metabolism was all increased in winter shoots, indicating that energy is critical for continuous growth under the relatively weak-light and low-temperature environment. Abiotic resistance-related proteins and free amino acids were also increased in abundance in the winter shoots, which possibly represents an adaptation response to winter conditions. These results allowed us to hypothesize a novel molecular mechanism of adaptation for this unique tender shoot evergrowing in winter.

Quantity of supplementary LED lightings regulates photosynthetic apparatus, improves photosynthetic capacity and enhances productivity of Cos lettuce grown in a tropical greenhouse.

Although cooling their rootzone allows year-round (temperate) vegetable production in Singapore's warm climate, these crops have frequently experienced increasingly unpredictable cloudy and hazy weather. Supplementary lighting with light-emitting diodes (LEDs) could be used to reduce the impacts of low light intensity. This study investigated the responses of temperate Cos lettuce (Lactuca sativa L.) to different quantities (photosynthetic photon flux density, PPFD of 0, 150, 300 µmol m-2 s-1) of supplementary LED lightings in the tropical greenhouse. Increasing light intensity significantly increased total leaf area, shoot and root fresh weight (FW) and dry weight (DW), total chlorophyll (Chl) and carotenoids (Car) contents, light-saturated photosynthetic CO2 assimilation rate (Asat) and transpiration rate (Tr). There were no significant differences in Fv/Fm ratio, total reduced nitrogen, specific leaf area (SLA) and PSII concentration among the three light treatments. However, there was an increasing trend with increasing light intensity for Chl a/b ratio, net photosynthetic O2 evolution rate (PN), cytochrome b6f (Cyt b6f), leaf total soluble protein and Rubisco concentrations. This study provides the basic understanding of photosynthetic apparatus and capacity of temperate crops grown under different supplementary LED lightings in the tropical greenhouse.

Transcriptional, metabolic, physiological and developmental responses of switchgrass to phosphorus limitation.

Knowing how switchgrass (Panicum virgatum L.) responds and adapts to phosphorus (P)-limitation will aid efforts to optimize P acquisition and use in this species for sustainable biomass production. This integrative study investigated the impacts of mild, moderate, and severe P-stress on genome transcription and whole-plant metabolism, physiology and development in switchgrass. P-limitation reduced overall plant growth, increased root/shoot ratio, increased root branching at moderate P-stress, and decreased root diameter with increased density and length of root hairs at severe P-stress. RNA-seq analysis revealed thousands of genes that were differentially expressed under moderate and severe P-stress in roots and/or shoots compared to P-replete plants, with many stress-induced genes involved in transcriptional and other forms of regulation, primary and secondary metabolism, transport, and other processes involved in P-acquisition and homeostasis. Amongst the latter were multiple miRNA399 genes and putative targets of these. Metabolite profiling showed that levels of most sugars and sugar alcohols decreased with increasing P stress, while organic and amino acids increased under mild and moderate P-stress in shoots and roots, although this trend reversed under severe P-stress, especially in shoots.

Investigation of Different Selenium Sources and Supplying Methods for Selenium Enrichment of Basil Vegetable (A Case Study under Calcareous and Non-calcareous Soil Systems).

BACKGROUND: Selenium (Se) is a crucial component of selenoaminoacids and selenoproteins. Therefore, Se-enriched agricultural products can reduce health complications induced by Se deficiency. OBJECTIVE: This research was carried out to investigate the effects of Se bio-enrichment on Basil grown in calcareous and non-calcareous soil systems and also to evaluate the changes in Se concentration in the soil after harvesting. METHODS: The experiment executed in two calcareous and one non-calcareous soil systems, and different Se application methods (control, soil application, seed inoculation, foliar application, and soil + foliar application) were administered. Selenobacteria, a plant growth-promoting rhizobacteria (PGPR), derived from the soil was used as a biofertilizer, compared to the other Se sources. RESULTS: The results showed that both soil types and the methods of Se application had significant effects (P ˂ 0.01) on root and shoot dry weights and concentrations of P, K, Zn, Fe, and Se in both of the root and shoot. Shoot dry weight of plants treated with foliar Se was maximum in the calcareous soil. Compared to the control treatment, foliar application of Se increased shoot Se content in both calcareous and non-calcareous soils by 242% and 204%, respectively. Furthermore, the increase in shoot Se concentration in calcareous soil induced by Se application increased the concentration of other nutrients in the shoot and root. Plant growth parameters and concentrations of nutrients were significantly increased by using selenobacter inoculum. CONCLUSION: The application of Se-containing compounds can improve vegetable quality. Considering the daily requirement of the human body for minerals and nutrients, enriching basil with Se can play an important role in community health. Moreover, some patents have reported the effectiveness of endophyte bacteria.

Carbohydrate saving or biomass maintenance: which is the main determinant of the plant's long-term submergence tolerance?

It is hypothesized that plant submergence tolerance could be assessed from the decline of plant biomass due to submergence, as biomass integrates all eco-physiological processes leading to fitness. An alternative hypothesis stated that the consumption rate of carbohydrate is essential in differing tolerance to submergence. In the present study, the responses of biomass, biomass allocation, and carbohydrate content to simulated long-term winter submergence were assessed in four tolerant and four sensitive perennials. The four tolerant perennials occur in a newly established riparian ecosystem created by The Three Gorges Dam, China. They had 100% survival after 120 days' simulated submergence, and had full photosynthesis recovery after 30 days' re-aeration, and the photosynthetic rate was positively related to the growth during the recovery period. Tolerant perennials were characterized by higher carbohydrate levels, compared with the four sensitive perennials (0% survival) at the end of submergence. Additionally, by using a method which simulates posterior estimates, and bootstraps the confidence interval for the difference between strata means, it was found that the biomass response to post-hypoxia, rather than that to submergence, could be a reliable indicator to assess submergence tolerance. Interestingly, the differences of changes in carbohydrate content between tolerant and sensitive perennials during submergence were significant, which were distinct from the biomass response, supporting the hypothesis that tolerant perennials could sacrifice non-vital components of biomass to prioritize the saving of carbohydrates for later recovery. Our study provides some insight into the underlying mechanism(s) of perennials' tolerance to submergence in ecosystems such as temperate wetland and reservoir riparian.