Hypocotyl Length Research Articles

Seed Germination and Seedling Growth Responses to Different Sources and Application Rates of Hydrothermal Carbonization Processed Liquid

Hydrothermal carbonization processed liquid (HTCPL) is a by-product of hydrothermal carbonization of biomass, which is used sparingly as natural fertilizer. A study was performed in the Faculty of Agriculture, Dalhousie University (Canada) between June 2019 and April 2020 to evaluate the elemental composition of HTCPL derived from three different biomass feedstock; namely, seafood compost; buckwheat (Fagopyrum esculentum), and willow (Salix babylonica). Different HTCPL application rates (0-10%) were tested on seed germination and seedling growth of pea (Pisum sativum), sunflower (Helianthus annuus), pac choi (Brassica rapa subsp. chinensis), kale (Brassica oleracea var. sabellica) and lettuce (Lactuca sativa). Elemental composition was higher in the HTCPLs compared to their respective feedstocks except for nitrogen. The 5% and 10% willow HTCPL with a pH between 3.8-4.0 inhibited seed germination and seedling growth compared to the other treatments with a pH range between 4.6-5.8. Kale, lettuce and sunflower radicle and hypocotyl growth were promoted following treatments of their respective seeds with seafood compost HTCPL while pea radicle and hypocotyl lengths were best promoted by 5% buckwheat and 10% seafood compost HTCPLs. Comparatively, 0.5% willow HTCPL increased surface area of seedling radicles while 1% willow and 0.5% buckwheat HTCPLs increased surface area of hypocotyls, irrespective of plant species. The distinction among the treatments was demonstrated on a 2-dimensional principal component analysis biplot that explained 89% of the variations in dataset. Overall, buckwheat HTCPL proved to be more effective at increasing seed germination and seedling growth compared to the other HTCPLs. The inhibitory effect of willow HTCPL at high application rate (5-10%) were obvious for all plant species. A comprehensive non-targeted chemical profile of HTCPL will help to explain mechanisms.

Pre-sowing seed treatment of narrow-leafed lupin against anthracnose and other diseases

The results of laboratory and field studies of the effectiveness of the Tirada SK disinfectant (suspension concentrate) against anthracnose seed infection and other lupine diseases are presented.The work was carried out in 2018-2020 in the Bryansk region. The object of study is the seeds, seedlings and crops of the Vityaz narrow-leafed lupin. In laboratory conditions, the effectiveness of the Tirada SK disinfectant (tiram 400 g / l + difenoconazole 30 g / l) was studied in three application doses (1.0; 1.5; 2.0 l / t). The biological effectiveness was evaluated by the number of infested seedlings grown in paper-polyethylene rolls compared to the control (without dressing). High biological effectiveness (100%) against anthracnose was shown by doses of 1.5 and 2.0 l / t. The highest overall germination (99.6%) and the number of seeds with strong seedlings (90.4%) were noted in the variant with a dose of 1.5 l / t. At the same time, the length of roots and hypocotyl of seedlings increased significantly (LSD05 = 0.69 and LSD05 = 0.51) by 18.0 and 1.0%, respectively. The field experiment was carried out in four repetitions, the plot area was 34 m2. The seeding rate was 1.2 1.2 million viable seeds / ha. The soil of the plot is grey forest with the humus content of 2.7%. The predecessor is spring sown cereals. Seed dressing with Tirada disinfectant at a consumption rate of 1.5 l / t was applied one month before sowing. The effectiveness of the disinfectant was evaluated in comparison with the control. The average biological effectiveness of the disinfectant against anthracnose infection was 94.3%. By the shiny pod phase, the number of affected pods was 5.7%, compared to 26.4% in the control. Plant infestation by Fusarium (Fusarium spp.) was reduced from 18.7% in the control to 11.8% in the experiment and by Rhizoctonia (Rhizoctonia solani Kuhn.) from 9.8% to 2.8%. The spread of grey rot and white rot on pods has been reduced by a factor of 2.4 and 2.8, respectively. The seed germination increased significantly (LSD05 = 0.71) by 8.1% and the safety of productive plants at harvest increased by 35.3%. A significant (LSD05 = 0.041) increase in seed yield was 0.82 t/ha, with a cost recovery of 7.15 rubles.

The Effect of polyethylene glycol concentration on some varieties of kenaf (Hibiscus cannabinus L.) in enhancing the germination viability

The purpose of this study was to see the interaction between the concentration of Polyethylene Glycol and various varieties of kenaf (Hibiscus cannabinus L.) On plant germination. This study used a completely randomized factorial design with 3 replications. The factors used for the study were varieties of kenaf (Karang Proso 6, Karang Proso 9 and Karang Proso 15) and the concentration of Polyethylene Glycol (0, 3, 5, and 7 ppm). Data were analyzed using analysis of variance (F test) using least significant difference (LSD) test of 5%. There was an interaction between the concentration of Polyethylene Glycol and kenaf varieties on germination power. Karang Proso 9 variety was consistent with several concentrations of Polyethylene Glycol which had higher germination compared to other varieties. Polyethylene Glycol concentration did not affect hypocotyl length, seed germination uniformity, dry weight of the varieties of Karang Proso 6, Karang Proso 9 and Karang Proso 15.

The stress induced caleosin, RD20/CLO3, acts as a negative regulator of GPA1 in Arabidopsis.

A stress induced calcium-binding protein, RD20/CLO3 interacts with the alpha subunit of the heterotrimeric G-protein complex in Arabidopsis and affects etiolation and leaf morphology. Heterotrimeric G proteins and calcium signaling have both been shown to play a role in the response to environmental abiotic stress in plants; however, the interaction between calcium-binding proteins and G-protein signaling molecules remains elusive. We investigated the interaction between the alpha subunit of the heterotrimeric G-protein complex, GPA1, of Arabidopsis thaliana with the calcium-binding protein, the caleosin RD20/CLO3, a gene strongly induced by drought, salt and abscisic acid. The proteins were found to interact in vivo by bimolecular fluorescent complementation (BiFC); the interaction was localized to the endoplasmic reticulum and to oil bodies within the cell. The constitutively GTP-bound GPA1 (GPA1QL) also interacts with RD20/CLO3 as well as its EF-hand mutant variations and these interactions are localized to the plasma membrane. The N-terminal portion of RD20/CLO3 was found to be responsible for the interaction with GPA1 and GPA1QL using both BiFC and yeast two-hybrid assays. RD20/CLO3 contains a single calcium-binding EF-hand in the N-terminal portion of the protein; disruption of the calcium-binding capacity of the protein obliterates interaction with GPA1 in in vivo assays and decreases the interaction between the caleosin and the constitutively active GPA1QL. Analysis of rd20/clo3 mutants shows that RD20/CLO3 plays a key role in the signaling pathway controlling hypocotyl length in dark grown seedlings and in leaf morphology. Our findings indicate a novel role for RD20/CLO3 as a negative regulator of GPA1.

New Evidence of Model Crop Brassica napus L. in Soil Clean-Up: Comparison of Tolerance and Accumulation of Lead and Cadmium.

The potential of the model crop Brassica napus L. (rapeseed) for the phytoremediation of soils polluted with metals was investigated at laboratory scale. The first step consists in the evaluation of the seed germination and growth of the Brassica napus L. plant in a controlled environment, followed by the determination of the photosynthetic pigments content represented by chlorophyll a and b and carotenoids. The degree of metal accumulation in rapeseed has been evaluated by the bioaccumulation factor (BAC), the bioconcentration factor (BCF) and the translocation factor (TF). Phytotoxicity tests were performed in Petri dishes with filter papers moistened with metal solutions in the range of 0 to 300 mg/L Pb(II) or Cd(II). At the highest concentration of the lead and cadmium treatments (300 mg/L), B. napus L. showed the lowest germination degree (56.67% and 43.33%, respectively). According to Tukey test results, Pb(II) concentrations of up to 300 mg/L do not significantly affect the length of the hypocotyls, whereas, in the case of Cd(II), the mean of the radicle and hypocotyl lengths of the seedlings are significantly affected compared to the mean of the control. In soil pot experiments, important changes have been obtained in the pigment content, especially in the case of cadmium. For both metals and for each treatment (100 to 1500 mg/kg Pb(II) and 1 to 30 mg/kg Cd(II)), a TF < 1 indicates an ineffective metal transfer from root to shoot. Finally, rapeseed can be considered a tolerant plant and a suitable candidate for Pb(II) and Cd(II) accumulation and for the phytostabilization of contaminated soil under the experimental conditions adopted in the present study.

Heat Stress Affects the Physiological and Biochemical Quality of Dalbergia nigra Seeds in vitro

Abstract The jacaranda of Bahia (Dalbergia nigra (Vell.) Allemão ex Benth) is an endemic tree of a Brazilian neotropical biodiversity hotspot and is of great ecological and economic interest. Given the threat of extinction due to timber overexploitation and climate change, the present study aimed to analyze the physiological and biochemical quality of D. nigra seeds exposed to heat stress. The seeds were sown in a test tube containing woody plant culture medium, kept in a biochemical oxygen demand chamber at 45°C for 0, 24, 48, 72, and 96 hours, and then maintained in the same chamber at 25°C for 30 days. Physiological analyses of moisture, electrical conductivity, germination speed index, normal and abnormal seedlings, seedling length, root length, hypocotyl length, collar diameter, seedling and root dry mass, and Dickson quality index revealed a drop in germination and vigor with prolonged heat stress, dropping from 95% to 0% between 0 and 96 hours. This was accompanied by a reduction in the content of carbohydrates, lipids, and proteins. Therefore, the vigor and quality of seedlings is negatively influenced by exposure to heat stress at 45°C.

Root Architecture, Growth and Photon Yield of Cucumber Seedlings as Influenced by Daily Light Integral at Different Stages in the Closed Transplant Production System

Optimizing light conditions for vegetable seedling production in a closed transplant production system is critical for plant growth and seedling production. Additionally, energy use efficiency should be considered by growers when managing the light environment. In the present study, cucumber seedlings (Cucumis sativus L. cv. Tianjiao No. 5) were grown under six different daily light integrals (DLIs) at 8.64, 11.52, 14.40, 17.28, 23.04, and 28.80 mol m−2 d−1 created by two levels of photosynthetic photon flux density (PPFD) of 200 and 400 μmol m−2 s−1 combined with photoperiod of 12, 16 and 20 h d−1 provided by white light-emitting diodes (LEDs) in a closed transplant production system for 21 days. Results indicated that quadratic functions were observed between fresh and dry weights of cucumber seedlings and DLI at 6, 11, 16, and 21 days after sowing. Generally, higher DLI resulted in longer root length, bigger root volume and root surface area accompanied with shorter plant height and hypocotyl length; however, no significant differences were observed in root length, root volume, and root surface area as DLI increased from 14.40 to 28.80 mol m−2 d−1. Photon yield based on fresh and dry weights decreased with increasing DLI. In conclusion, increased DLI resulted in compact and vigorous morphology but reduced photon yield of cucumber seedlings produced in a closed transplant production system. In terms of plant growth and energy use efficiency, DLI at 14.40–23.04 mol m−2 d−1 was suggested for cucumber seedling production in the closed production system. Additionally, different control strategies should be applied at different growth stages of cucumber seedlings.

Evaluation of Trichoderma spp. Isolates in Cocoa Seed Treatment and Seedling Production.

Isolates of Trichoderma spp., a soil fungus, has been used to control diseases and promote plant growth, reducing the use of chemicals in the production of seedlings of different plant species. We evaluated the effect of some Trichoderma spp. isolates on seed treatment and seedling production of Theobroma cacao. Five isolates from the Amazon region were tested. In laboratory, the following variables were evaluated for seed treatments: germination, germination speed index, radicle and hypocotyl lengths, and fungi incidence. In nursery, the following forms of application were tested: via seeds; in the substrate at pre-planting; monthly in post-planting substrate, and also their combination. The following was evaluated: height, diameter, number of leaves, root length, leaf area, and shoot dry mass and root system. Inoculation with Trichoderma increased the length of the radicle and hypocotyl and showed no fungi in the seeds. In seedlings, some treatments increased height and plant root dry mass. The use of Trichoderma was beneficial for seeds and appeared favorable for T. cacao production.

Identification of BR biosynthesis genes in cotton reveals that GhCPD-3 restores BR biosynthesis and mediates plant growth and development.

Brassinosteroid (BR) synthesis genes in different cotton species was comprehensively identified, and the participation of GhCPD-3 in the BR synthesis signaling pathway for regulating plant development was verified. Brassinosteroid is a natural steroidal phytohormone that plays fundamental roles in plant growth and development. In cotton, detailed characterization and functional validation of BR biosynthesis genes remain rare. Here, 16, 8 and 9 BR biosynthesis genes were identified in Gossypium hirsutum, Gossypium raimondii and Gossypium arboreum, respectively, and their phylogenetic relationships, gene structures, conserved motifs of the encoded proteins, chromosomal locations were determined and a synteny analysis was performed. Gossypium hirsutum and Arabidopsis BR biosynthesis genes closely clustered in the phylogenetic tree and fragment duplication was likely the primary cause promoting gene family expansion in G. hirsutum. Gene Ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analysis showed their relevance as BR biosynthesis genes. GhCPD-3 was highly expressed in roots and stems and the loci of single nucleotide polymorphisms (SNPs) were significantly associated with these traits.Ectopic overexpression of GhCPD-3 in the cpd91 Arabidopsis mutant rescued the mutant phenotype by increasing plant height and leaf size in comparison to those of cpd91 and WT plants. Moreover, overexpressed GhCPD-3 in cpd91 mutants showed greater hypocotyl and root lengths than those of cpd91 and WT plants under light and dark conditions, respectively, indicating that BR actively promotes hypocotyl and root growth. Similar to CPD (CONSTITUTIVE PHOTOMORPHOGENIC DWARF), GhCPD-3 restores BR biosynthesis thereby mediating plant growth and development.

Bioherbicidal Activity and Metabolic Profiling of Potent Allelopathic Plant Fractions Against Major Weeds of Wheat-Way Forward to Lower the Risk of Synthetic Herbicides.

The productivity of major field crops is highly compromised due to weed infestation. Inefficient weed management practices and undue and excessive use of chemical herbicides have drastically contaminated the environment and human health, in addition to resistance development in weed species. Therefore, utilization of allelopathic plants to explore phytochemicals as potent organic alternatives to such chemical herbicides has become indispensable. The current study evaluates the comparative bio-herbicidal potential of methanolic extracts of castor (Ricinus communis), artemisia (Artemisia santolinifolia), wheat (Triticum aestivum), and sorghum (Sorghum bicolor) to suppress growth of major weeds, i.e., wild mustard (Sinapis arvensis), Italian ryegrass (Lolium multiflorum), and carrot grass (Parthenium hysterophorus). The results demonstrated a concentration-dependent effect on weeds’ growth. Overall, in vitro seed germination was reduced from 60 to 100% in response to 5% (w/v) extract concentration. Significant reduction in radicle length, hypocotyl length, and fresh biomass of the weeds was also observed. A strong inhibitory effect was seen in in vivo pot experiments, revealing that application of 10–20% methanolic extracts induced permanent wilting and substantial reduction in the chlorophyll content of weeds along with 20–80% increase in oxidative stress. Artemisia showed the most significant allelopathic effect, on account of highest phenolic and flavonoid contents, followed by castor, wheat, and sorghum, against S. arvensis, L. multiflorum, and P. hysterophorus, respectively. Phytochemical analysis, through high-performance liquid chromatography (HPLC), also exhibited a correlation between extract’s phytotoxicity and their antioxidant potential due to their major constituents (rutin, quercetin, catechin, gallic acid, vanillic acid, syringic acid, ferulic acid, p-hydroxy benzoic acid, p-coumaric acid, and sinapic acid), among the total of 13 identified in methanolic fractions. Comprehensive profiling of allelochemicals with liquid chromatography–mass spectrometry (LC-MS) determined 120, 113, 90, and 50 derivates of phenolic acids, flavonoids, and alkaloids, reported for the first time through this study, demonstrating significant allelopathic potential of the targeted plant fractions, which can be explored further to develop a sustainable bio-herbicidal formulation.

Effects of BrMYC2/3/4 on Plant Development, Glucosinolate Metabolism, and Sclerotinia sclerotiorum Resistance in Transgenic Arabidopsis thaliana.

MYC2/3/4, known as a basic helix–loop–helix (bHLH) transcription factor, directly activate the genes involved in diverse plant development and secondary metabolites biosynthesis. In this study, we identified and cloned five MYC paralogs (BrMYC2/3-1/3-2/4-1/4-2) from Chinese cabbage (Brassica rapa ssp. pekinensis). In-silico analyses for the physicochemical properties suggested that BrMYC2/3-1/3-2/4-2/4-3 are unstable hydrophobic and acidic proteins, while BrMYC4-1 is an unstable hydrophobic and basic protein. BrMYC2/3/4 belong to the bHLH superfamily and are closely related to AthMYC2/3/4 orthologs that mediate the regulation of various secondary metabolites. It was demonstrated that BrMYC2/3/4-GFP fusion protein localized in the nucleus and expression levels of five BrMYC2/3/4 homologous genes all elevated relative to control (Ctrl). When expressed in Arabidopsis under the control of 35S promoter, each of the BrMYC2/3-1/3-2/4-1/4-2 transgenes differentially influenced root and shoot elongation, vegetative phase change, flowering time, plant height and tiller number after flowering, and seed production. Despite the variation of phenotypes between the transgenic lines, all the lines except for BrMYC4-2 exhibited shorter seed length, less seed weight, higher accumulation of glucosinolates (GSs), and resistance to Sclerotinia sclerotiorum than Ctrl. Notably, BrMYC2 overexpression (OE) line significantly reduced the lengths of root and hypocotyl, seed length, and weight, along with faster bolting time and strikingly higher accumulation of total GSs. Accumulation of GSs at the highest levels in the BrMYC2OE line conferred the highest resistance to S. sclerotiorum. Unlike BrMYC3OE and BrMYC4OE, BrMYC2OE stimulated the growth of plant height after fluorescence. The results of this study point to the BrMYC2 overexpression that may provide a beneficial effect on plant growth and development via plant resistance to the fungal pathogen.

Co-inoculation with a product based on native microorganisms improves germination and seedling growth of Phaseolus vulgaris L.

Agricultural products based on native microorganisms represent an ecological alternative to traditional chemical fertilizers for enhancing growth and crop yield. This study aimed to evaluate the effect of the product based on native microorganisms IHPLUS® on germination, emergence, and primary leaf formation of Phaseolus vulgaris L. seedlings. The treatments consisted of a control (immersion in distilled water) and nine treatments that were the combination of IHPLUS® at three concentrations and three immersion times. The application of IHPLUS® significantly increased the percentage of germination, mainly in the first days. After 7 d, the germination rate and root and hypocotyl lengths increased in almost all treatments compared to control seedlings. The beneficial effects of IHPLUS® on the germination of P. vulgaris may be partially attributed to changes on seedling metabolism due to an increase in α-amylase activity and in the content of reducing sugars and soluble proteins. Results suggest that IHPLUS® may act as an enhancer of germination in common beans that might lead to rapid seed germination, uniform seedling growth, and better seedling establishment and crop productivity.

Plant extracts of Cleome viscosa L. as biostimulants of the in vitro germination of two varieties of pepper (Capsicum annuum L.)

The aim of the work was to evaluate the biostimulant effect of plant extracts of Cleome viscosa L. on the in vitro germination of two varieties of pepper (Capsicum annuum L.). A bioassay was set up on a completely randomized design with a control and 18 treatments with three samples each, evaluating the effect on the dynamics and percentage of germination, radicle length and hypocotyl length. The chemical families present in the extracts were determined by phytochemical characterization. For the length of the radicle and the hypocotyl, the extracts with the best potentialities in the Verano 1 variety are those obtained from the root and stem, although the concentrations with the best influence on both indicators are 1 and 3 of the root extracts. Differences in the richness of chemical families were verified in the extracts with the best results, although the best composition was obtained in those of the root and stem, showing the presence of free amino acids in all cases. Cleome viscosa is promising for obtaining products with a biostimulant effect on the varieties of pepper studied, obtaining a better effect when root, stem and whole plant extracts are applied.

Bioaugmentation and bioaugmentation-assisted phytoremediation of heavy metal contaminated soil by a synergistic effect of cyanobacteria inoculation, biochar, and purslane (Portulaca oleracea L.).

In recent decades, soil contamination with heavy metals has become an environmental crisis due to their long-term stability and adverse biological effects. Therefore, bioremediation is an eco-friendly technology to remediate contaminated soil, which the efficiency requires further research. This study was designed to comparatively investigate two strategies: bioaugmentation by using a cyanobacterial species (Oscillatoria sp.) and bioaugmentation-assisted phytoremediation by using Oscillatoria sp. and purslane (Portulaca oleracea L.) for the bioremediation of soil contaminated by heavy metals (Cr (III), Cr (VI), Fe, Al, and Zn). Various quantities of biochar (0.5, 2, and 5% (w/w)) were used as an amendment in the experiments to facilitate the remediation process. The results of the bioaugmentation test showed that applying biochar and cyanobacteria into contaminated soil significantly increased the chlorophyll a, nitrogen, and organic carbon contents. In contrast, the extractable fractions of Cr (III), Cr (VI), Zn, Al, and Fe declined compared with those of the control treatment. The highest reduction content (up to 87 %) in the extractable portion was obtained for Cr (VI). The development of longer root and hypocotyl lengths and vigour index from lettuces and radish seeds grown in the remediated soil confirmed the success of remediation treatments. Moreover, the findings of the bioaugmentation-assisted phytoremediation test displayed a reduction in the bioavailable fraction of Cr (III), Cr (VI), Zn, Al, and Fe. Cr (III) presented the highest reduction (up to 90 %) in metal bioavailability. With cyanobacteria inoculation and biochar addition, the shoot and root lengths of purslane grew 4.6 and 3-fold while the heavy metal accumulation decreased significantly. Besides, these treatments enhanced the tolerance index (TI) quantities of purslane whereas diminished its bioaccumulation coefficient (BAC) and bioconcentration factor (BCF) values. For all heavy metals (except Zn), translocation factor (TF) and BAC values were found to be less than 1.0 at all treatments, indicating the successful phytoextraction by the purslane. These results suggest that the purslane can be considered an excellent phytoextracting agent for soils contaminated with heavy metals.

Effects of Growing Cycle and Genotype on the Morphometric Properties and Glucosinolates Amount and Profile of Sprouts, Microgreens and Baby Leaves of Broccoli (Brassica oleracea L. var. italica Plenck) and Kale (B. oleracea L. var. acephala DC.)

Some new foods (sprouts, microgreens and baby leaf) of the brassica genus are appreciated for their nutritional and nutraceutical values. The aim of this experimental trial was to improve the nutraceutical traits of these foods by evaluating the effects of the climatic condition, genotype, and plant growth stage on the development of greater quality in relation to these new foods. The morphometric and glucosinolates (GLSs) traits of three traditional Italian cultivars of Brassica oleracea crops, such as broccoli (B. oleracea var. italica), namely the traditional Sicilian landrace ‘Broccolo Nero’ (BN) and the commercial ‘Cavolo Broccolo Ramoso Calabrese’ (CR), as well as the commercial kale cultivar ‘Cavolo Laciniato Nero di Toscana’ (CL) (B. oleracea var. acephala DC.), were evaluated in an unheated greenhouse in Catania during the end of 2019 and the beginning of 2020. Plant growth was studied at different phenological stages—from seeds to sprouts, microgreens, and baby leaves—over two growing cycles, one in autumn–winter and the other in spring–summer. ‘Broccolo Nero’ (BN) broccoli showed more rapid growth and biomass production than the other two cultivars evaluated (i.e., weight, hypocotyl length, and leaf width). The GLS profile varied significantly (p &lt; 0.05), in relation both to plant’s growth stage and to genotype. The highest amount of glucoraphanin was detected for BN microgreens and baby leaves, about 8 µmol g−1 d.w., whereas glucobrassicin and its related derivatives were about 14 µmol g−1 d.w. in microgreens and baby leaves of CL and about 15 µmol g−1 d.w. and 10 µmol g−1 d.w. for glucoraphanin in CR, respectively. These new foods can also be produced at home with simple and cheap equipment

Natural attenuation and bioremediation of chlorpyrifos and endosulfan in periurban horticultural soils of Buenos Aires (Argentina) using microcosms assays

Chlorpyrifos and endosulfan degradations were compared at laboratory scale in three different soils: a conventional horticultural (SH), an accredited 25 year organic horticultural (SA) and a reference soil (SR) used as control. Chlorpyrifos and α-endosulfan degradation half-lives were, respectively, in the range 7.2 d – 9.8 d and 4.4 d – 6.6 d, finding no statistical difference for any soil. In the case of β-endosulfan, a difference was found in degradation half-lives, being: SR (25.8 d) < SA (49.1 d) < SH (102.1 d), indicating some difficulty, in the case of the traditional horticultural soil, to biodegrade this isomer. Three different biostimulants: poultry litter (CP), bokashi (fermented organic matter, BKS) and ramial chipped wood (BRF) were added to soil to explore the increase of chlorpyrifos and endosulfan biodegradation. While no improvement was observed for chlorpyrifos, all biostimulants favoured endosulfan degradation. In the case of BKS endosulfan half-life was reduced ca. three times (considering both isomers). Seed germination bioassays were performed using soil and biostimulant to evaluate potential ecotoxicological impacts. CP had a significant inhibitory effect on germination, hypocotyl elongation, radicle length and hypocotyl length, while BKS and BRF parameters were more similar to the control performance.

Dioecious hemp (Cannabis sativa L.) plants do not express significant sexually dimorphic morphology in the seedling stage

Some economically important crop species are dioecious, producing pollen and ovules on distinct, unisexual, individuals. On-the-spot diagnosis of sex is important to breeders and farmers for crop improvement and maximizing yield, yet diagnostic tools at the seedling stage are understudied and lack a scientific basis. Understanding sexual dimorphism in juvenile plants may provide key ecological, evolutionary and economic insights into dioecious plant species in addition to improving the process of crop cultivation. To address this gap in the literature, we asked: can we reliably differentiate males, females, and co-sexual individuals based on seedling morphology in Cannabis sativa, and do the traits used to distinguish sex at this stage vary between genotypes? To answer these questions, we collected data on phenotypic traits of 112 C. sativa plants (50 female, 52 male, 10 co-sexuals) from two hemp cultivars (CFX-1, CFX-2) during the second week of vegetative growth and used ANOVAs to compare morphology among sexes. We found males grew significantly longer hypocotyls than females by week 2, but this difference depended on the cultivar investigated. Preliminary evidence suggests that co-sexual plants may be distinguished from male and female plants using short hypocotyl length and seedling height, although this relationship requires more study since sample sizes of co-sexual plants were small. In one of the cultivars, two-week old male plants tend to produce longer hypocotyls than other plants, which may help to identify these plants prior to anthesis. We call for increased research effort on co-sexual plants, given their heavy economic cost in industrial contexts and rare mention in the literature. Our preliminary data suggests that short hypocotyl length may be an indicator of co-sexuality. These results are the first steps towards developing diagnostic tools for predicting sex using vegetative morphology in dioecious species and understanding how sexual dimorphism influences phenotype preceding sexual maturity.

Plant growth biostimulant activity of the green microalga Desmodesmus subspicatus

The plant biostimulant activity of the green microalga Desmodesmus subspicatus was investigated, focusing on its potential application to organic crops. Different concentrations of D. subspicatus biomass suspensions were applied to tomato seedlings (Solanum lycopersicum) via a foliar spray. The treatments promoted root growth and foliar area, which increased when the suspension was applied at concentrations of 1 g L−1 and 0.4 g L−1, respectively. To elucidate the major constituents responsible for this potential activity, the biomass of D. subspicatus was submitted to aqueous extraction and dialysis (1 kDa cut-off), giving rise to the non-dialyzable fraction E (12.3%). Size-exclusion chromatography performed on fraction E using a Bio-Gel P-2 column yielded six subfractions. Gas chromatography-mass spectrometry (GC–MS) and nuclear magnetic resonance (NMR) analyses of the E subfractions revealed the presence of glycosides as major constituents (approx. 81%), including one acidic glycoside, [6-sulfo-α-D-quinovopyranosyl-(1→1)-glycerol], and two neutral galactosyl glycosides, [α-D-galactopyranosyl-(1→6)-β-D-galactopyranosyl-(1→1)-glycerol] and [β-D-galactopyranosyl-(1→1)-glycerol]. Ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) analyses of fraction E resulted in the identification of the phytohormone zeatin (35 μg g−1). To evaluate the biostimulant potential of fraction E, different concentrations (0.5, 1.0, 1.5, and 2.0 g L−1) were tested for their effects on tomato seed germination, hypocotyl volume, and length. All tested concentrations induced increased hypocotyl lengths and volumes compared with standard treatment (water), at rates equivalent to those in response to a commercial product derived from Ascophyllum nodosum brown seaweed. These results indicated that the biomass suspension and aqueous extract of D. subspicatus showed plant growth biostimulant activity. Glycosides, together with zeatin, may play important roles in biostimulant activity.

Genotypic differences in aluminum tolerance of cowpea accessions utilizing germination parameters

One of the major factors which limit the productivity of cowpea on acid soils is aluminum toxicity. Reliable methods for identifying genetic variation for its tolerance is indispensable. Genetic variability for aluminum tolerance in 10 accessions of cowpea were studied in the laboratory. Fifteen seeds of each accession were sown in sterilized petri dishes containing filter papers and 5 ml of AlCl3 at four levels (0, 50, 100 and 200 µm) and replicated three times in a completely randomised design (CRD). Petri dishes were incubated under room temperature in the dark for 48 hours. After 48 hours, they were exposed to photoperiod of 12 hr. / 12 hr. (day/night) at room temperature for another 48 hours. At day four after sowing, data were collected on percentage germination, number of roots per shoot, fresh weight of shoot, root length and hypocotyl length and fresh weight of shoot. Data were subjected to statistical analysis and accessions were arranged on their tolerance to aluminum stress by means of tolerance indices. Analysis of variance revealed significant effect of accessions on all parameters. Treatment was significant for all excluding percentage germination. Treatment by accession was significant for number of roots and root length. The observed genetic variation in cowpea for aluminum stress could be exploited by hybridisation to establish tolerant lines. Selection based on high heritability and GAM in percentage germination, hypocotyl length and number of roots in cowpea under aluminum stress can be exploited for selection.

The use of indigenous bacterial community as inoculant for plant growth promotion in soybean cultivation

ABSTRACT We characterized the bacterial community in shoot and rhizosphere of healthy adult soybean plants grown in two differentially managed soils. Then, these communities were transplanted to seeds to assess their effect on seedling development. The bacterial communities of inoculated soybean seedlings were assessed through 16S rRNA amplicon sequencing and seedlings’ growth was measured. The diversity in the bacterial consortium inoculum prepared from the rhizosphere was higher than those from the shoot. However, the application of bacterial consortium in seedling had no influence on diversity. The resulting bacterial community of seedlings inoculated with bacterial consortium presented an enrichment of specific plant growth-promoting groups, such as Gammaproteobacteria (Enterobacter, Pseudomonas, and Xanthomonas). The predicted potential functions showed an increased abundance of functions related to plant protection and nutrition. The application of bacterial consortium from the shoot of soybean plants grown in the soil with a previous history of soybean cultivation increased the seedling radicle length, hypocotyl length, and total dry weight by 44%, 30%, and 29%, respectively. Our study showed that selecting a consortium of indigenous microbes as inoculants is a potential approach to enhance the use and impacts of plant beneficial microorganisms on plant growth and possibly productivity.