Cotyledon Stage Research Articles

Stomatal Density Variation Within and Among Different Soybean Cultivars Across Various Growth Stages

Stomata regulate CO2 and water vapor exchange between leaves and the atmosphere, serving as a vital indicator of climate change resilience. Therefore, understanding the difference in stomatal numbers and patterns among different soybean cultivars across growth stages is essential to comprehending the complex mechanisms underlying soybean adaptation to climate change. The accurate measurements of stomatal density in soybean leaves are essential to understanding the complexity of stomatal density by environmental conditions. We demonstrated that the five epidermal sections and five microscopic images taken from both sides of each epidermal section at each leaf position (tip, middle, and bottom) were sufficient for stomatal measurements. Furthermore, we investigated variations in stomatal density among leaflet locations (left, right, and central) and leaf position across different growth stages. Notably, while there was no significant variation between the two leaves of the vegetative cotyledon (VC) stage and among the three leaflets of the V1 (first trifoliate) to V4 (fourth trifoliate) growth stages, leaves of the VC stage exhibited the lowest stomatal density, whereas those of the V4 stage exhibited the highest stomatal density. These findings could serve as a valuable tool for evaluating stomatal density, analyzing physiological differences under adverse climatic conditions, and phenotyping a large-scale population to identify the genetic factors responsible for stomatal density variations in soybean genotypes.

Laser weeding of common weed species

The massive use of herbicides since the 1950s has resulted in increasing problems with herbicideresistant weeds and pollution of the environment, including food, feed, and water. These side effects have resulted in political pressures to reduce herbicide application. The European Commission aims to reduce the use and risk of chemicals and more hazardous pesticides in the EU. Therefore, new weed control methods are in demand. Laser weeding might be an alternative to replace or supplement herbicides and other weed control methods in an Integrated Weed Management (IPM) strategy. This work aimed to investigate how increasing laser energy affected common weeds when the apical meristem was exposed to irradiation at the early stages of development. A 50 W thulium-doped fibre laser with a diameter of 2 mm and a wavelength of 2 µm was used. The highest efficacy of laser irradiation was achieved when the grass weed (Alopecurus myosuroides) had one leaf and the dicot species were at the cotyledon stage. There was a large difference between the species’ susceptibility to irradiation probably caused by differences in morphology and growth habit. At the 4-leaf stage, most of the species regrew after irradiation. Laser weeding may be a solution to replace or supplement other weed control methods in some crops, but in general the weeds must be irradiated when they are at the cotyledon to 2-leaf stage to avoid regrowth.

The Effect of Different Harvest Times on Phenolic Content and Antioxidant Activity in Some Microgreens

Microgreens, which have only become popular during the last decades, are rich in phytochemicals, including phenolic compounds, which act as antioxidants. The study aimed to examine the effects of two different harvest times (cotyledon [embryonic leaves] and 1.5-true leaf stage) of five microgreens on the bioactive compounds in terms of antioxidant capacity and total phenolics. The total phenolic components ranged from 60.9 to 2153.2 mg GAE g-1 in cotyledon leaves, whereas the value varied from 96.2 to 2113.9 mg GAE g-1 in the true leaves of microgreens. Increases in the phenolic content of the first true leaves in dill and chia were detected as 57.8% and 29.6% compared to the cotyledon leaf. Among the cotyledon microgreens, the maximum phenolic content was detected in the garden cress. The antioxidant capacity of the cotyledon and true leaf stages ranged between 485.4±2.3-1985.67±24.9 µg g-1 and 508.87±5.3-2393.56±12.6 µg g-1, respectively. The maximum antioxidant capacity was detected in radish, followed by garden cress. The biggest variation between the cotyledon and first true leaves in the study was observed for red beetroot. This study revealed the alteration in the phenolic content and antioxidant activity of five cultivars based on growth stages of cotyledonary and true leaves in microgreen form.

Cytological, Physiological, and Transcriptomic Analyses of the Leaf Color Mutant Yellow Leaf 20 (yl20) in Eggplant (Solanum melongena L.)

Leaf color mutants are ideal materials for studying chlorophyll metabolism, chloroplast development, and photosynthesis in plants. We discovered a novel eggplant (Solanum melongena L.) mutant yl20 (yellow leaf 20) that exhibits yellow leaves. In this study, we compared the leaves of the mutant yl20 and wild type (WT) plants for cytological, physiological, and transcriptomic analyses. The results showed that the mutant yl20 exhibits abnormal chloroplast ultrastructure, reduced chlorophyll and carotenoid contents, and lower photosynthetic efficiency compared to the WT. Transcriptome data indicated 3267 and 478 differentially expressed genes (DEGs) between WT and yl20 lines in the cotyledon and euphylla stages, respectively, where most DEGs were downregulated in the yl20. Gene Ontology (GO) analysis revealed the “plastid-encoded plastid RNA polymerase complex” and the “chloroplast-related” terms were significantly enriched. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the significantly enriched DEGs were involved in flavone and flavonol biosynthesis, porphyrin and chlorophyll metabolism, etc. We speculated that these DEGs involved in significant terms were closely related to the leaf color development of the mutant yl20. Our results provide a possible explanation for the altered phenotype of leaf color mutants in eggplant and lay a theoretical foundation for plant breeding.

Scanning Electron Microscopy Analysis of Tea’s Embryo Axis Explant Cultured on Murashige and Skoog Medium Containing 2,4-Dichlorophenoxyacetic acid

Camellia sinensis L. is an important crop in Indonesia as healthy beverage that contains several secondary metabolism compounds, such as polyphenols and catechins. Tissue culture including somatic embryogenesis and organogenesis has been used for propagating plant for various needs. In this present short-communication, scanning electron microscopic (SEM) analysis of tea was conducted and discussed. This study aimed to investigate surface ultrastructure of TRI2025 embryo axis tea clone cultured on Murashige and Skoog (MS) medium containing 2,4-Dichlorophenoxyacetic acid (2,4-D). The results revealed two different forms of explant’s development, i.e. somatic embryo and transitional form between somatic embryogenesis and organogenesis; or called by “Globular-like Structure” (GLS). Surface ultrastructure analysis of somatic embryo and GLS revealed respectively many stages of somatic embryo development i.e. globular, torpedo, and cotyledon stage, and leaf development form GLS regeneration.

First Report of Foliar Nematode (Aphelenchoides pseudobesseyi) on Soybean in Colombia

Soybean (Glycine max L.) is produced in over 70,000 ha in the Altillanura Region, eastern Colombia (Agronet 2023). From 2018 to 2020, foliar symptoms like green stem and foliar retention of soybean, which in Brazil can cause up to 100% soybean yield losses (Meyer et al. 2017), were observed in soybean fields in Colombia. During 2020, samples from symptomatic plants in reproductive stages (R1-R8) were collected from different commercial soybean fields in the Altillanura Region. Over 200 samples were processed, using an incubation method described in Coyne et al. (2014). Nematodes were recovered from photosynthetic leaf tissues and enlarged nodes/buds with population densities ranging from 13 to 132 and 36 to 936 nematodes/10g, respectively. Adult females were morphologically and molecularly characterized as Aphelenchoides pseudobesseyi (Oliveira et al. 2019; Subbotin et al. 2020). Female body length (n = 20) ranged from 653.3 to 806.3 μm (mean = 723 μm ± 52.7), stylet length from 11.0 to 12.3 μm (11.8 μm ± 0.3), body diameter from 14.8 to 17.9 μm (16.3 μm ± 1.1), post-uterine sac length from 38.7 to 51.9 μm (44.6 μm ± 5.1), vulva to anus from 145.5 to 223.2 μm (172.2 μm ± 22.4), and 26% of the vulva-anus distance. Genomic DNA was extracted (QIAGEN DNeasy® Blood & Tissue kit) from a pool of nematodes. The D2A/D3B (Tenente et al. 2004) primers were used to amplify and sequence the D2/D3 expansion region of the 28S rRNA gene. PCR product (~759 bp) was purified, sequenced, deposited in GenBank (OQ930285), and compared to previously deposited sequences (e.g., KX356756, KY510840, KY510839, KY510841, KT692694, KY510842, MH187565) by means of the BLAST algorithm. Similarly, 988F and 18SR-Burs (De Jesus et al. 2016) primers were used to amplify and sequence the near full-length 18S RNA gene (SSU). PCR product was purified, sequenced, deposited in GenBank (OQ954344), and compared to previously deposited sequences (e.g., KT454962, KT943534, KT943535, KY510835, KY510836, KY510837, KY510838, MH187565). Phylogenetic Bayesian analysis (Ronquist et al. 2012) of the of the D2/D3 and 18S regions placed this nematode from Colombia in the A. pseudobesseyi clade (PP = 100). To fulfill a modified Koch’s postulates, the A. pseudobesseyi population described above was used in a greenhouse assay. In total, 120 soybean plants (cv. Flor Blanca) were infected with 200 A. pseudobesseyi (females + males)/plant. Briefly, at cotyledon stage (VC), 50 µl aliquot containing 50 A. pseudobesseyi was delivered onto each cotyledon and unifoliolate leaves (200 nematodes/plant). Sterile water was delivered to 80 plants which served as control. Plants were kept in the greenhouse at approximately 25°C and covered with clear plastic bag for 72 h to maintain over 90% relative humidity. After 15, 30, 45, and 60 days, soybean plants (n = 20) were processed, A. pseudobesseyi quantified, and the average reproduction factor (final population/initial population) was 0.1, 2.9, 14.0, and 1.8, respectively. Infected plants showed symptoms of blistering leaves with malformation (midrib vein twist), and A. pseudobesseyi was not observed in control plants. To our knowledge, this is the first report of A. pseudobesseyi parasitizing soybean buds and leaves in Colombia. Soybean is an important commodity for the Altillanura Region, and it is important to monitor the risk posed by this nematode. Furthermore, a better understanding of the nematode-host interaction and epidemiology in Colombia soybean producing regions is needed.

Characterization of yellow‐green leaf1 mutant for improved phosphorus use efficiency and rapid offspring screening in Tartary buckwheat

AbstractLeaf color mutations provide valuable genetic resources for elucidating the molecular regulatory mechanisms of plant growth and serve as efficient tools for screening offspring in crossbreeding. In this study, a Tartary buckwheat (Fagopyrum tataricum) mutant with yellow‐green leaves (yl1) was isolated from 60Co‐γ‐radiation mutation bank. Compared to wild type (WT), yl1 showed similar biomass and yield, despite a lower chlorophyll content and net photosynthetic rate. However, yl1 displayed significantly higher total phosphorus content after 14 days of medium and low phosphorus treatment. By using yl1 as the maternal parent, hybrid offspring could be visually distinguished at the cotyledon stage. Genetic analysis revealed that the yl1 phenotype was attributed to a single recessive mutation. Combined metabolome and transcriptome analysis identified 205 differential expressed metabolites (DEMs) and 123 differential expressed genes enriched in 30 pathways or metabolisms between yl1 and WT. Remarkably, the upregulation of SPX3, 5PTase2, PHO1, PAP3, PAP2, PAP7, and IPAP16, which are involved in enhancing phosphorus absorption, assimilation, transport, and remobilization, along with PLDζ1, GDPD1, MGD2, and NPC4L, which contribute to improving lipid metabolism, collectively resulted in high accumulation of 41 phosphorus‐containing DEMs (including 37 lipids) in yl1. This study emphasizes the potential of yl1 for effective screening of offspring and uncovers the interplay between photosynthesis and lipid metabolism, providing valuable insights to improve phosphorus use efficiency in Tartary buckwheat.

Effect of osmoregulatory on the secondary somatic embryogenesis of cocoa (Theobroma cacao L.)

Cocoa (Theobroma cacao L.) is the raw material for the worldwide chocolate industry. To ensure high quality and efficient field production, the industry relies on a uniformity of elite cocoa plants, which can be achieved through vegetative propagation methods like somatic embryogenesis. However, the low yield rate in the multiplication and regeneration of cocoa plants remains a challenge for basic research. To obtain a greater number of secondary somatic embryos (SSE) in cocoa, the effect of three osmoregulators on the disc cells of primary somatic embryos (PSE) of cocoa was studied. PSE was induced from cocoa staminodes of genotype I52. Epicotyls were selected from PSE at the torpedo and cotyledon stages, segmented into 3 mm discs, and placed in a secondary callus growth medium. The explants were transferred to embryo development medium 3, where they were exposed to the osmoregulatory polyethylene glycol (PEG), mannitol, and sorbitol at the following concentrations: 0%, 1%, 3%, and 5%. D-Mannitol at 3% and D-Sorbitol at 1% increased the number of SSE at the torpedo, globular, and cotyledon stage per explant. The culture medium with 1% PEG significantly increased the formation of SSE in the globular and cotyledonal stages. The results presented a positive effect of the osmoregulators on the formation of cocoa SSE.

Informing the operation of intelligent automated intra-row weeding machines in direct-sown sugar beet (Beta vulgaris L.): Crop effects of hoeing and flaming across early growth stages, tool working distances, and intensities

The effective management of intra-row weeds is necessary to preserve crop yields in slow-to-establish direct-seeded crops like sugar beet, and suitable non-chemical control options are limited. However, the advent of automated intelligent intra-row weeding machines has provided a promising solution. These machines identify individual crop plants and selectively hoe or flame weed the between-crop zone, leaving the intra-row close-to-crop zone untreated. To characterize crop tolerance to intra-row weeding and describe optimal tool working intensities and distances, five pot experiments were performed using sugar beet as the test crop. From cotyledon through the four-leaf stage, hoeing could be implemented as close as 1 cm to the center of sugar beet plants before adverse crop effects were observed. Based on crop injury measured, direct flaming of sugar beet at the cotyledon stage is not advised at any intensity, although flaming tolerance was observed to increase with crop growth stage. Direct flaming did not affect sugar beets when the propane dose was ≤0.74 kg km−1 at the two-leaf stage, ≤1.49 kg km−1 at the four-leaf stage, and ≤5.95 kg km−1 at the six-leaf stage. Sugar beets at the two-leaf growth stage were not damaged by flaming at distances ≥1.5 cm at a propane dose of 3.72 kg km−1. Field experiments will be necessary to confirm these operational guidelines for next-generation automated intelligent weeders.

New mutations of flower shape in Nigella damascena L., its pleiotropic effects and patterns of inheritance

Two mutants with short sepals were identified after ethyl methanesulfonate treatment of Nigella damascena seeds. In one of them (“shs1” gene = short sepal 1), isolated from the line with double flowers, the sepals, in addition to reduced size, were divided into several rounded lobes, which granted the flower an original rose-like appearance of ornamental value. Another mutant with reduced sepals (“shs2” gene = short sepal 2) was isolated from the line with simple flowers. The allelism test showed that these two genes were non-allelic. Both mutants as pollen parents were crossed with the same line with single flowers. In a dihybrid cross, simple flower, non-reduced sepals (wild type) × double flower, reduced sepals (“shs1” gene) F1 hybrids demonstrated a wild phenotype. F2 progeny, in addition to two parental classes, showed two recombinant classes in a 9:3:3:1 ratio, indicating that flower shape and sepal size were inherited monogenously and independently, and the plant with rose-like flowers was a double recessive homozygote. Reduced sepals (“shs2” gene) in crosses with the single flower line of wild type were inherited as a monogenic recessive trait, showing a 3:1 segregation ratio in F2. Both mutant genes had a number of similar pleiotropic effects, which, however, were different in strength. Thus, both mutant genes shortened leaf segments, divided the cotyledon leaves into several lobes, and caused disturbances in the female generative sphere, leading to a lack of seed setting. At the same time, the identification of mutants as early as at the cotyledon stage, due to the pleiotropic effect, makes it possible to select and maintain them, especially with regard to the mutant with rose-like flowers, which is highly decorative.

Effect of spermidine, glutamine, and proline on somatic embryogenesis and silver nanoparticles supplied culture improved rhizome formation of Panax vietnamensis var. langbianensis

Lang Bian ginseng (Panax vietnamensis var. langbianensis) is a rare and traditional herbal medicine with many pharmacological activities. It was first discovered by Duy et al. (2016) in Lam Dong province, Vietnam. Until now, there has been only one publication on Lang Bian ginseng micropropagation via somatic embryogenesis (Anh et al., 2022). However, this study still had limitations, including the small number of somatic embryos and the time-consuming. This study investigated the effect of spermidine, glutamine, and proline on the enhancement of somatic embryogenesis (SE) of Lang Bian ginseng using thin cell layer culture technology. The results showed that the optimal SE rate and the number of somatic embryos per explant were achieved on MS medium supplemented with 0.01 mM spermidine in leaf explants (93.32 % and 54.20 embryos, respectively) and petiole explants (96.66 % and 68.80 embryos, respectively) and higher compared to these in other treatments, including control, glutamine, and proline treatments. Besides, adding 0.01 mM spermidine to the culture medium also improved the quality of somatic embryos, mainly cotyledonary stage, through an enhanced synthesis of antioxidant enzymes [catalase (CAT) and superoxide dismutase (SOD), and ascorbate peroxidase (APX)]. In addition, the fluctuations of endogenous hormones during initiation and maturation of SE derived from 0.01 mM spermidine treatment were recorded. Endogenous CKs (ZEA, 2iP, KIN, mT), IAA, and GA3 concentrations were the highest during the induction stage in both explants. Meanwhile, the remaining endogenous hormones (MEL, ABA, and SA) exhibited no inevitable fluctuation trends. In addition, IAA was only detected at the induction stage of SE in both explants. Moreover, cotyledonary somatic embryos derived from 0.01 mM spermidine treatment grew well in MS medium supplemented with 1.2 mg/L AgNPs.

Non-targeted metabolomic evaluations during seed germination and seedling growth in Salicornia brachiata (Roxb.) under saline conditions

Experimental studies were conducted for metabolomic profiling during seed germination and seedling development in Salicornia brachaita under saline conditions. The results revealed accumulation of sucrose, mannose, glycerol, methionine, tryptophan, glycerol, protocathechoic acid, and mannonic acid in germinating seeds. Abundance of rhamnose, glucose, glutamine, fructose, ornithine, quininic acid, proline and ketoglutaric acid were recorded during emergence of radical (EoR) and cotyledonary stage (CS) at 50% strength of seawater (SW) salinity. Higher levels of myo-inositol, ethanolamine, isoleucine and talose at 48 hours (hrs) of imbibition, EoR and CS stages; while glycine, tyrosine and turanose were so at CS stage only. Under 200 mM NaCl, richness of stearic acid, quercetin, leucine, erythritol and psicose were noted at 48 hrs of imbibition followed by EoR stage. Fructose, ornithine, mannitol, asparagine, mallic acid, glucose and citric acid were abundant at EoR whereas aminobutanoic acid, hexanedioic acid and tyramine were so at CS stage. Among detected metabolites maximum number of metabolites showed hits with amioacyl-tRNA biosynthesis pathway and the amino acid biosynthesis pathway had maximum impact during seedling development. Role of metabolic pathways (including amino acid metabolism) and differential expression of genes related to these pathways are suggested in meeting the energy needs for varied biological activities during seed germination and subsequent seedling development in S. brachiata.

In Vitro Conversion of Coffea spp. Somatic Embryos in SETIS™ Bioreactor System.

Somatic embryogenesis (SE) is an excellent example of mass plant propagation. Due to its genetic variability and low somaclonal variation, coffee SE has become a model for in vitro propagation of woody species, as well as for large-scale production of vigorous plants that are advantageous to modern agriculture. The success of the large-scale propagation of an embryogenic system is dependent on the development, optimization, and transfer of complementary system technologies. In this study, two successful SE systems were combined with a SETIS™ bioreactor immersion system to develop an efficient and cost-effective approach for the in vitro development of somatic embryos of Coffea spp. This study used an efficient protocol for obtaining somatic embryos, utilizing direct and indirect SE for both C. canephora and C. arabica. Embryos in the cotyledonary stage were deposited in a bioreactor to complete their stage of development from embryo to plant with minimal manipulation. Following ten weeks of cultivation in the bioreactor, complete and vigorous plants were obtained. Different parameters such as fresh weight, length, number of leaves, and root length, as well as stomatal index and relative water content, were recorded. In addition, the survival rate and ex vitro development of plantlets during acclimatization was assessed. The best substrate combination was garden soil (GS), peat moss (PM), and agrolite (A) in a 1:1:0.5 ratio, in which the bioreactor-regenerated plants showed an acclimatization rate greater than 90%. This is the first report on the use of SETIS™ bioreactors for the in vitro development of somatic embryos in Coffea spp., providing a technology that could be utilized for the commercial in vitro propagation of coffee plants. A link between research and innovation is necessary to establish means of communication that facilitate technology transfer. This protocol can serve as a basis for the generation and scaling of different species of agroeconomic importance. However, other bottlenecks in the production chains and the field must be addressed.

An Ensemble Learning Model for Detecting Soybean Seedling Emergence in UAV Imagery.

Efficient detection and evaluation of soybean seedling emergence is an important measure for making field management decisions. However, there are many indicators related to emergence, and using multiple models to detect them separately makes data processing too slow to aid timely field management. In this study, we aimed to integrate several deep learning and image processing methods to build a model to evaluate multiple soybean seedling emergence information. An unmanned aerial vehicle (UAV) was used to acquire soybean seedling RGB images at emergence (VE), cotyledon (VC), and first node (V1) stages. The number of soybean seedlings that emerged was obtained by the seedling emergence detection module, and image datasets were constructed using the seedling automatic cutting module. The improved AlexNet was used as the backbone network of the growth stage discrimination module. The above modules were combined to calculate the emergence proportion in each stage and determine soybean seedlings emergence uniformity. The results show that the seedling emergence detection module was able to identify the number of soybean seedlings with an average accuracy of 99.92%, a R2 of 0.9784, a RMSE of 6.07, and a MAE of 5.60. The improved AlexNet was more lightweight, training time was reduced, the average accuracy was 99.07%, and the average loss was 0.0355. The model was validated in the field, and the error between predicted and real emergence proportions was up to 0.0775 and down to 0.0060. It provides an effective ensemble learning model for the detection and evaluation of soybean seedling emergence, which can provide a theoretical basis for making decisions on soybean field management and precision operations and has the potential to evaluate other crops emergence information.

ABA spray on Arabidopsis seedlings increases mature plants vigor under optimal and water-deficit conditions partly by enhancing nitrogen assimilation.

Here, we report the effects of a single abscisic acid (ABA) spray on Arabidopsis seedlings on growth, development, primary metabolism, and response to water-deficit stress in adult and next-generation plants. The experiments were performed over 2 years in two different laboratories in Iran and South Africa. In each experiment, fifty 7-day-old Arabidopsis seedlings were sprayed with 10 μM ABA, 1 mM H2 O2 , distilled water, or left without spraying as priming treatments. Water-deficit stress was applied on half of the plants in each treatment by withholding water 2 days after spraying. Results showed that a single ABA spray at the cotyledonary stage significantly increased plant biomass and delayed flowering. The ABA spray significantly enhanced drought tolerance so that the survival rate after rehydration was 100 and 33% in the first and the second experiments, respectively, for ABA-treated plants compared to 35 and 0% for water-sprayed plants. This enhanced drought tolerance was not inheritable. Metabolomics analyses suggested that ABA probably increases the antioxidant capacity of the plant cells and modulates tricarboxylic acid cycle toward enhanced nitrogen assimilation. Strikingly, we also observed that the early water spray decreases mature plant resilience under water-deficit conditions and cause substantial transient metabolomics perturbations.

Performance of Drift-Reducing Nozzles in Controlling Small Weed Seedlings with Contact Herbicides

In many EU countries, spray applications should comply with increasingly stringent requirements regarding the drift reduction class of spray nozzles. Many farmers fear that the use of drift-reducing nozzles producing coarse droplet spectra may compromise the performance of contact herbicides on small weed targets. This study examined the effects of various ISO 03 drift-reducing flat-fan nozzles (pre-orifice and single and dual flat-fan air induction nozzles) differing in spray drift reduction class and spray pressure (2.5 bar, 5.0 bar) on (1) spray coverage, (2) droplet characteristics and (3) efficiency of contact herbicides bentazon and phenmedipham against cotyledon and 2-leaf stage plants of Chenopodium album and Solanum nigrum. Performance was compared to that of an ISO 03 standard flat-fan nozzle producing a finer droplet size spectrum. All sprayings were performed at a spray volume of 200 L ha−1. In most dose–response experiments, several drift-reducing flat-fan nozzles performed equally well as standard flat-fan nozzles, regardless of herbicide, spray pressure, growth stage or weed species. However, droplet size spectra of air-induction nozzles were too coarse for an adequate spray coverage and efficient application of contact herbicides on cotyledon stage plants of S. nigrum. In addition, the performance of air-induction nozzles in controlling difficult-to-wet C. album weeds with phenmedipham was better at 5.0 bar than at 2.5 bar. In contrast with droplet size characteristics, spray coverage characteristics determined on water sensitive papers were not good proxies for estimating the biological efficiency of contact herbicides. Air induction nozzles at 5.0 bar allow efficient control of 2-leaf targets, but nozzles emitting finer droplet spectra, such as pre-orifice nozzles, should be preferred for controlling cotyledon stage weeds at low-herbicide doses.

In Vitro Mass Propagation of Coffee Plants (Coffea arabica L. var. Colombia) through Indirect Somatic Embryogenesis

Coffea arabica is one of the two most consumed coffee species in the world. Micropropagation through somatic embryogenesis has allowed the large-scale propagation of different coffee varieties. However, the regeneration of plants using this technique depends on the genotype. This study aimed to develop a protocol for the regeneration of C. arabica L. var. Colombia by somatic embryogenesis for its mass propagation. Foliar explants were cultured on Murashige and Skoog (MS) supplemented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BAP), and phytagel for inducing somatic embryogenesis. In total, 90% of the explants formed embryogenic calli with a culture medium containing 2 mg L-1 of 2,4-D, 0.2 mg L-1 BAP, and 2.3 g L-1 phytagel. The highest number of embryos per gram of callus (118.74) was obtained in a culture medium containing 0.5 mg L-1 2,4-D, 1.1 mg L-1 BAP, and 5.0 g L-1 phytagel. In total, 51% of the globular embryos reached the cotyledonary stage when they were cultured on the growth medium. This medium contained 0.25 mg L-1 BAP, 0.25 mg L-1 indoleacetic acid (IAA), and 5.0 g L-1 of phytagel. The mixture of vermiculite:perlite (3:1) allowed 21% of embryos to become plants.

Morphological, physiological, cytological characteristics and agricultural potential of colchicine induced autotetraploid plants in safflower

Safflower (Carthamus tinctorius L.) is one of the important oilseed and bio-energy crops. All of the safflower cultivars in the world have diploid genomes (2n= 2x= 24). In this research, autotetraploidy induction in safflower was performed by colchicine treatments to the emerging shoot tips at the cotyledonary stage. As a result of flow cytometric analyses performed in the C2 progenies, autotetraploids (4x= 48) had DNA content of 4.88 pg 2C-1, while diploids (2x= 24) had 2.29 pg 2C-1. The autotetraploids in C2 generation exhibited bigger stomata size (33.40 μm to 46.90 μm in length) and a higher chloroplast number (9.5 to 17.2 in the guard cells), but less stomatal density (17.98% to 16.67% in index) compared to their diploid counterparts. However, autotetraploidy reduced the pollen viability from 80.24% to 16.20%, and seed set rate from 35.06% to 7.01% per capitula. As a result, autotetraploid plants were able to produce very few seeds despite the high unit seed size and weight in their heads. While oil content of the large-seeded autotetraploids was significantly lower, by two-fold, (26.37% to 13.23% in the whole seeds) than the small-seeded diploids, fatty acid composition was not significantly influenced by autopolyploidization.

Production of Lavender (Lavandula Angustifolia) Plants from Somatic Embryos Developed from its Seedlings Leaf Callus

The current study succeeded in producing the lavender (Lavandula angustifolia) plant from somatic embryos induced by the leaves callus of its seedlings, The results of soaking its dormant seeds in a solution of gibberellic acid at concentrations (0, 0.1, 0.25, 0.5, 1.0) gm l -1 for 24 hours showed the superiority of the concentration 0.5 g L -1 in stimulation the germination rate that reached 75% after 6 days comparing with other treatments and control that had 20% germination after 13 days. This study was able to initiated callus from seedling leaves when were placed on MS solid medium supplemented with by added 3.0 mg L-1 NAA and 10 mg L -1 BA after 20 days, Initiated callus was characterized by its yellowish-green color and friable texture, and when its masses were removed and placed on the same media, it produced well-growth cultures that were perpetuated every 15 days. After the second sub-culturing, the first stages of somatic embryos appeared, the spherical stage, which later developed into the heart,then torpedo and cotyledon stages and produced when placed individually on MSO medium, Intact lavender plants after 30 days were characterized by their good growth and density of leaves.

A Model for Identifying Soybean Growth Periods Based on Multi-Source Sensors and Improved Convolutional Neural Network

The identification of soybean growth periods is the key to timely take field management measures, which plays an important role in improving yield. In order to realize the discrimination of soybean growth periods under complex environments in the field quickly and accurately, a model for identifying soybean growth periods based on multi-source sensors and improved convolutional neural network was proposed. The AlexNet structure was improved by adjusting the number of fully connected layer 1 and fully connected layer 2 neurons to 1024 and 256. The model was optimized through the hyperparameters combination experiment and the classification experiment of different types of image datasets. The discrimination of soybean emergence (VE), cotyledon (VC), and first node (V1) stages was achieved. The experimental results showed that after improving the fully connected layers, the average classification accuracy of the model was 99.58%, the average loss was 0.0132, and the running time was 0.41 s/step under the optimal combination of hyperparameters. At around 20 iterations, the performances began to converge and were all superior to the baseline model. Field validation trials were conducted applying the model, and the classification accuracy was 90.81% in VE, 91.82% in VC, and 92.56% in V1, with an average classification accuracy of 91.73%, and single image recognition time was about 21.9 ms. It can meet the demand for the identification of soybean growth periods based on smart phone and unmanned aerial vehicle (UAV) remote sensing, and provide technical support for the identification of soybean growth periods with different resolutions from different sensors.