Stratified Seeds Research Articles

Advancing grape breeding through an in vitro embryo germination technique without cold stratification

In grape breeding programs, the extensive planting of seedlings is a crucial aspect. However, grape seeds display distinct dormancy traits, necessitating a prolonged cold stratification process for dormancy release. In order to enhance the efficiency of breeding programs, this study presents an innovative in vitro embryo germination technique that eliminates the requirement for cold stratification of seeds. The method involves the disruption of peripheral tissue in grape seed embryos using a straightforward mechanical technique, resulting in the efficient production of a substantial quantity of seed embryos，with a germination rate of up to 88% for these isolated embryos. These embryos are subsequently cultured in vitro to facilitate germination into seedlings, thereby eliminating the need for cold stratification. Consequently, grape seedlings can be obtained within a significantly reduced timeframe of 30–38 d, expediting the overall grape breeding process. This novel approach not only accelerates grape hybridization but also streamlines the selection of new grape varieties, contributing to an efficient and time-sensitive breeding methodology.

Adaptation to Environmental Stressors Conferred by Gene Copy Number Variation in Herbicide Resistant Amaranthus palmeri

Many rampant agricultural weeds have been found to contain gene copy number variation, a genetic adaptation that can facilitate the evolution of stress resistance. Amaranthus palmeri is a highly competitive and problematic agricultural weed in the United States which continues to naturalize, spreading northward to Canada. A.palmeri has gained attention due to its rapid evolution of herbicide resistance— a mechanism conferred by gene copy number variation of EPSPS. Researchers hypothesize that this gene is contained within an amplicon alongside other stress tolerance related genes. This raises the question of whether increased EPSPS gene copy number is associated with higher tolerance to environmental stressors, beyond herbicide stress. To prepare for addressing this hypothesis, I conducted a pilot project testing the ideal conditions for germination of A.palmeri. I planted 200 seeds divided between greenhouse and growth chamber environments. Many seeds benefit from a period of cold as a signal to break dormancy, thus, each category was further divided into two treatments: control and cold stratified (seeds were incubated in a –23 cold room for a week). I was interested in whether the increased consistency of temperature, light intensity, and photoperiod provided by a growth chamber, relative to a greenhouse, would increase germination rates. Results indicate that greenhouse grown seedlings had a 71% germination rate and within each treatment, 86% of cold stratified plants germinated while only 56% of the control group germinated. Whereas in the growth chamber, surprisingly only 26% of plants germinated with a breakdown of 22% cold stratified and 30% control. Thus, to germinate enough plants for a large-scale experiment, I chose to cold stratify seeds and grow them in the greenhouse for my undergraduate thesis. In this common garden experiment, I am currently growing 500 plants which will be divided into four stress treatment categories: control, salinity, drought, and salinity x drought. Using phenotypic measurements and digital droplet PCR (ddPCR) to quantify EPSPS gene copy number, I will test for a possible association between plants with a higher tolerance to these simulated environmental stressors and the presence of increased EPSPS gene copy number.

Breaking of seed dormancy in ash gourd (<i>Benincasa pruriens</i>) through fruit storage and seed treatments

The dormancy in seeds collected from freshly harvested ash gourd [Benincasa pruriens f. hispida (Thunb.) de Wilde & Duyfjes] fruits reduces the seed quality and field performance viz. early germination, faster seedling establishment and vigorous seedling growth. Post harvest storage of fruits and different physical and chemical methods are useful in breaking seed dormancy in cucurbits. The present study was carried out during winter (rabi) 2020–21 and rainy (kharif) seasons of 2021–22 at the Agricultural Research Station (Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu), Vaigai Dam, Tamil Nadu to identify the optimal duration of post-harvest fruit storage and dormancy-breaking method for reducing seed dormancy in ash gourd cv. CO 1. Experiment was conducted in a randomized block design (RBD) with 3 replications. Firstly, the results revealed that the seeds extracted from the fruits, which were stored for 60 days after harvest, exhibited the best field performance, viz. early emergence, higher field emergence, faster rate of emergence and more seedling length, seedling dry weight, seedling vigour index, and viability indicating that prolonged storage can effectively reduce seed dormancy. Secondly, among different dormancy-breaking treatments, warm stratification of seeds at 40–50°C for 5 days and soaking of seeds in 500 ppm ethrel for 16 h remarkably improved the field performance, indicating the usefulness of these methods in improving seed quality characteristics in ash gourd. Farmers can use ethrel to break dormancy in ash gourd.

Plant Growth Hormones and Micro-Tuberization in Breaking the Seed Dormancy of Bunium persicum (Boiss.) Fedts.

Bunium persicum is a valuable medicinal plant with limited production but high market demand. It thrives predominantly in high-altitude regions. The main challenges hindering its widespread cultivation are seed dormancy and a lengthy seed-to-seed cycle, making its large-scale cultivation difficult. Six genotypes of Bunium persicum were collected from different altitudes to evaluate its germination behavior and seed dormancy. The study was conducted during 2020-23 and comprised three experiments (viz., seed germination under an open field, controlled conditions, and micro-tuberization). Under open field conditions, germination percent was genotype dependent, and the highest germination percentage, root length, and shoot length were recorded in Shalimar Kalazeera-1. Germination behavior assessment of the Bunium persicum revealed that treatment T9 (GA3 (25 ppm) + TDZ (9 µM/L)) is effective in breaking the dormancy of Bunium persicum as well as in obtaining a higher germination percent for early development of the tubers. Similarly, with regard to the effect of temperature and moisture conditions, stratification under moist chilling conditions showed effectiveness in breaking seed dormancy as the germination percentage in stratified seeds was at par with the most efficient growth hormone. With regard to the in vitro micro-propagation, direct regeneration showed multiple shoot primordia at the base of the tubers without intervening callus phase from the MS medium supplemented with BA (22.2 µM) and NAA (13.95 µM) 4 weeks after sub-culturing. Similarly, medium supplemented with JA (8.0 mg/L) and BA (22.2 µM) produced well-organized somatic embryos with shiny surfaces, which appeared at the swelled basal portion of apical stems. Further, the combination of JA (6.0 mg/L) and BA (22.2 M) was effective in developing the micro-tubers and also enhanced the weight and length of Bunium persicum micro-tubers.

The effect of prolonged stratification and shading on the emergence of Pseudotsuga menziesii (Mirb.) Franco seedlings

The Douglas fir has been cultivated in Europe since the mid-19th century, but its artificial regeneration leads to a low yield of seedlings. It could be improved by prolonged pre-sowing treatment (cold stratification of seeds) or the early shading of sowings, so that their effect on five Douglas fir seed lots and their emergence and growth of seedlings were analysed. One lot came from the USA; four lots came from the Czech Republic. The germination capacity and germination rate were analysed for seed without pre-sowing treatment and seed after 21-day and 49-day stratification. The emergence rate was tested for variants of the 21-day and the 49-day stratification (shaded and unshaded treatment) and for autumn sowing (unshaded treatment). The results show that the maximal germination capacity of full seeds is achieved after the 21-day stratification. The prolonged 49-day stratification increases the germination rate, especially in seed lots with lower vitality. The biggest seedlings, in terms of length and biomass of the above-ground part and the biomass of the root system, emerged from seeds sown in autumn. The combination of the 49-day stratification of seeds and the 3-week shading after spring sowing can accelerate seedling emergence and increase the emergence rate of seedlings; seedlings achieve more biomass and length of the above-ground part, the root system compared to unshaded seedlings or seedlings emerged from 21-day stratified seeds. Comparable or better results were achieved from autumn sowing.

Effects of warming on seed germination of woody species in temperate secondary forests.

Seed germination, a critical stage of the plant life cycle providing a link between seeds and seedlings, is commonly temperature-dependent. The global average surface temperature is expected to rise, but little is known about the responses of seed germination of woody plants in temperate forests to warming. In the present study, dried seeds of 23 common woody species in temperate secondary forests were incubated at three temperature sequences without cold stratification and after experiencing cold stratification. We calculated five seed germination indices and the comprehensive membership function value summarized the above indicators. Compared to the control, +2 °C and +4 °C treatments without cold stratification shortened germination time by 14% and 16% and increased the germination index by 17% and 26%, respectively. For stratified seeds, +4 °C treatment increased germination percentage by 49%, and +4 °C and +2 °C treatments increased duration of germination, germination index, and shortened mean germination time by 69%, 458%, 29% and 68%, 110%, 12%, respectively. The germination of Fraxinus rhynchophylla and Larix kaempferi were most sensitive to warming without and with cold stratification, respectively. Seed germination of shrubs were the least sensitive to warming among functional types. These findings indicate warming (especially extreme warming) will enhance the seedling recruitment of temperate woody species primarily via shortening germination time, particularly for seeds undergone cold stratification. In addition, shrubs might narrow their distribution.

How temperature, substrate, and stratification periods influence Ilex paraguariensis embryonic development

Aiming to develop a new stratification protocol for yerba mate seeds, we evaluated how different combinations of temperature, substrate, and period influence the embryonic development of the species, compared to fresh seeds and conventionally stratified seeds. We measured the seeds’ moisture content and performed a tetrazolium test to evaluate embryo viability and embryonic development. Seeds’ initial moisture content was 10.1% and reached 40.6% after stratification. We observed more embryos in advanced development stages after stratification in all treatments, indicating that the protocols used were adequate for the species and have a great potential to be explored for yerba mate seedling.

RNA-seq study reveals the signaling and carbohydrate metabolism regulators involved in dormancy release by warm stratification in Paris polyphylla var. yunnanensis.

Long-term seed dormancy of Paris polyphylla var. yunnanensis limits its large-scale artificial cultivation. It is crucial to understand the regulatory genes involving in dormancy release for artificial cultivation in this species. In this study, seed dormancy of Paris polyphylla var. yunnanensis was effectively released by warm stratification (20°C) for 90 days. The freshly harvested seeds (dormant) and stratified seeds (non-dormant) were used to sequence, and approximately 147 million clean reads and 28,083 annotated unigenes were detected. In which, a total of 10,937 differentially expressed genes (DEGs) were identified between dormant and non-dormant seeds. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) classification revealed that the majority unigenes involved in signaling transduction and carbohydrate metabolism. Of them, the signaling transduction-related DEGs were mainly hormones-, reactive oxygen species (ROS)-, and transcription factor (TF)-related genes. The largest number of signaling transduction-related DEGs were auxin-responsive genes (SAUR, AUX/IAA, and ARF) and AP2-like ethylene-responsive transcription factor (ERF/AP2). Moreover, at least 29 DEGs such as α-amylase (AMY), β-glucosidase (Bglb/Bglu/Bglx), and endoglucanase (Glu) were identified involving in carbohydrate metabolism. These identified genes provide a valuable resource to investigate the molecular basis of dormancy release in Paris polyphylla var. yunnanensis.

Recovery and Germination of Malus sieversii (Ledeb.) M. Roem. (Rosaceae) Seeds after Ingestion by Cattle, Horses, and Sheep

Livestock can transport seeds long distances by endozoochory due to their large home range and capacity to move among different habitats. However, differences in digestive system and body size between different livestock species may result in variations in the dispersal of domestic livestock. To test such effects, we explore the effects of endozoochorous seed dispersal of Malus sieversii by three livestock: cattle, horse, and sheep in the Ili Botany Garden, northwest of China. We collected seeds of M. sieversii and fed them to cattle, horses and sheep. After feeding, we collected all the seeds from their feces every 24 h for 6 days and determined the seed recovery percent, mean retention time, and germination percent of seeds after the effects of the digestive tracts of those three livestock species. Seed recovery percent in three livestock species feces were cattle (CS) (54.05%) > horse (HS) (4.83%) > sheep (SS) (0.45%). The mean retention time of seeds in the digestive tract of cattle, horses and sheep were 53 h, 57 h, and 45 h. The seed weight and seed coat thickness decreased significantly after the treatment of the digestive tract. After 80 days cold stratification of seeds, the germination percent of CK, CS, and HS were 61%, 69%, and 18%, respectively. The results indicated cattle is an effective seed disperser of M. sieversii, with a recovery and germination percent in endozoochorous seed dispersal by cattle than that of horse and sheep. Our findings may also provide a theoretical basis about regarding seed-centric grazing management decisions and keeping horse and sheep out of pastures during the fruit of M. sieversii shedding period.

Statistical indicators of seed reproduction of apple <i>(MALUS MİL L.)</i> species introduced on apsheron

We have studied effective methods of seed reproduction of some species of apple trees in the condition of Apsheron. The newly introduced and available in the collection of the Central Botanical Garden of ANAS 23 species of wild apples were taken as research material. Experiments were carried out with both stratified and non-stratified seeds. The germination rate of the studied species was different. As a result, it turned out that in order to obtain good germination of seeds of apple varieties introduced in Absheron, they should be sown either early autumn, or for various reasons (climate, lack of time, etc.), it is better to stratify the seeds and to shorten the germination time it is advisable to sow in spring. Statistical analysis was carried out on the basis of the obtained results. In the course of statistical processing, the statistical programs PAST, SPSS 16. were used. Cluster analysis of samples was carried out using the Ward method based on the Evklid index of genetic distance. According to morphometric and mass parameters, the seeds of the studied species were divided into 3 main groups with 5 values of the genetic distance. The values of statistical indicators were also determined for other studied characteristics of seeds in apple species. The parametrs include minimum and maximum values, mean, standard error, standard deviation, coefficient of variation. And the studied characters are the width, length, and weight of the seeds. This indicates that among the three traits studied between species, the mass trait has greater variability, in other words, higher genetic diversity. That is, the trait of the seed mass of the studied species makes it possible to distinguish more species. It is known that by crossing genetically distant species, a hybrid with new traits can be obtained, i.e. with a high effect of heterosis. From this point of view, high-quality species are selected from the species included in the clusters, and by crossing them with species from other clusters, a hybrid with a high heterosis effect can be obtained. With this method of selection, it is possible to gradually obtain new varieties of high quality.

Использование гуминовых препаратов для выращивания посадочного материала древесных растений в аридном регионе

Abstract. The purpose is to study the effect of the organic preparation “Ekobiosfera” of various spectrum of action on morphophysiological processes during the germination of seeds of Pinus nigra subsp. pallasiana (Lamb.), Quercus robur L., Robinia pseudoacacia L., Calligonum aphyllum (Pall.). Research methodology. The experiments were carried out in laboratory conditions in three variants of applying the drug – 10, 15 and 20 ml/l of water, stratified and scarified seeds were soaked in a working solution for 12 hours to a day, their growth and development were observed in the laboratory in the plant rooms, and immediately before planting in the substrate (zonal lightchestnut soil + peat) conditions. The repetition of the experiment is three-fold, with control, 20 plants in each variant of the experiment. Results. In the course of research, the authors have established the necessity and expediency of using the drug “Ekobiosfera” as a biostimulator for the growth of phytomass and roots. The most optimal dosage for the growth and development of samples of woody species is 10 and 15 ml/l. With an increase or decrease in the dose, plants experienced wilting and inhibition of growth, a lower percentage of preservation. Also, the positive effect of LED lighting on seedlings of oak and Crimean pine was found. For robinia pseudoactation, the selection of the optimal dose of the drug and lighting is required, for the leafless juzgun, the drug is ineffective due to the inconsistency of soil and climatic conditions of cultivation, which requires further study. Thus, the positive effect of the organic preparation “Ekobiosfera” on the growth and development of coniferous and deciduous species for nursery breeding in the arid zone was noted. Scientific novelty. In the conditions of the arid region, the effect of the organic preparation “Ekobiosfera” on tree species was studied for the first time. Taking into account the reaction of the seeds of the studied plants, effective doses of introducing a growth stimulant have been developed, optimal lighting options for plants in the process of growing have been proposed.

Synchronized Seed Germination and Seedling Growth of Black Cumin

Black cumin (Nigella sativa) is an important medicinal plant in the pharmacological industry. It is cultivated on a commercial scale, but its seeds have a slow, unsynchronized germination rate. Enhancing seed germination is crucial for improving the production of black cumin. The influence of presowing treatments [gibberellic acid (GA3), potassium nitrate, salicylic acid, and stratification at 4 °C] on seed germination was assessed. Seed germination was determined daily for 30 days, and germination parameters, including final germination percentage (FGP), corrected germination rate, number of days to reach 50% of FGP, and seedling length vigor index, were evaluated. Endogenous contents of GA3 and abscisic acid (ABA) in nonstratified and stratified seeds were estimated using high-performance liquid chromatography (HPLC) and seedling growth was determined in 45-day-old seedlings. All presowing treatments tended to boost early germination for the first 10 days compared with the control. Low concentrations of GA3 at 0.25 g·L−1 also increased FGP (80%) compared with the control group (65.55%). Stratification for 4 weeks provided the greatest FGP value at 95.56%, and stratification for 3 weeks proved to be the most effective treatment for optimal seedling growth. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis patterns of stratified seeds revealed the alteration in intensities of 13 bands and the appearance of a new band (180 kDa) indicating a change in the synthesis of proteins during stratification. Moreover, stratification modulated the endogenous GA3 and ABA contents of black cumin seeds, which alleviated the physiological dormancy and resulted in high and synchronized seed germination.

Cool-Warm Temperature Stratification and Simulated Bird Digestion Optimize Removal of Dormancy in Rosa rugosa Seeds.

Rosa rugosa Thunb. has been explored multi-function in medicinal, edible, cosmetic, ornamental and ecological etc. However, R. rugosa natural populations have recently declined substantially in China, besides of global climate change, this species also has the defect of limiting the reproduction of itself such as the hard-to-release seed dormancy. In this study, only 30% of R. rugosa seeds were viable, and the others were incompletely developed or diseased seeds. Without stratification, morphologically complete viable seeds imbibed water but those seeds could not germinate even after seed husk removal under suitable condition to exhibit a physiological dormancy. After cold (4°C) and warm (18 ± 2°C) stratification, macromolecular substances containing carbon or nitrogen accumulated, and respiration, antioxidant enzyme activity, and gibberellin (GA3) /abscisic acid (ABA) and auxin (IAA)/ABA ratios increased significantly in seeds. Water absorption also increased as endocarps softened. Thus, physiological dormancy of seed was broken. Although warm and cold stratification increased separation between endocarp and embryo, the endocarp binding force was removed insufficiently, because only 10.20% of seeds germinated. Therefore, stratified seeds were treated with simulated bird digestion. Then, folds and cracks in loosened endocarps increased permeability, and water absorption rate increased to 64.43% compare to 21.14% in cold and warm stratification treatment. With simulated digestion, 24.20% of radicles broke through the endocarp with plumules and cambiums to develop into seedlings. Thus, the seed dormancy type of R. rugosa is physiological as seeds imbibed water and possessed fully developed embryos with a low growth potential in combination with a mechanical constraint from the endocarp. Cold stratification helped remove physiological dormancy, and additional warm stratification accelerated the process. The optimal stratification treatment was 4°C for 45 days followed by 18 ± 2°C for 15 days. After warm and cold stratification, simulated bird digestion broke the mechanical constraint from the seed covering layers. Based on this research, production of R. rugosa seedlings can be greatly increased to help protect the species from further declines.

Metabolome profiling of stratified seeds provides insight into the regulation of dormancy in Davidia involucrata

Dove tree (Davidia involucrata), a tertiary vestige species, is well-adapted to cool conditions. Dormancy in D. involucrata seed lasts for an extremely long period of time, typically between 3 and 4 years, and this characteristic makes the species an excellent model for studying the mechanisms of seed dormancy. The molecular mechanisms governing germination control in D. involucrata are still unknown. Seed stratification have been reported to enhance germination in recalcitrant seeds. We performed a widely targeted metabolome profiling to identify metabolites and associated pathways in D. involucrata seeds from six different moist sand stratification durations (0–30 months) using the ultra-high-performance liquid chromatography-Q Exactive Orbitrap-Mass spectrometry. There was an increasing germination rate with prolonged stratification durations (12–30 months). Furthermore, we detected 10,008 metabolites in the stratified seeds. We also detected 48 differentially accumulated metabolites (DAMs) between all stratification periods in the seeds, with 10 highly conserved metabolites. Most of the differentially accumulated metabolites between unstratified and stratified seeds were enriched in purine metabolism, pyrimidine metabolism, flavone and flavonol biosynthesis, phenylpropanoid biosynthesis, and arginine biosynthesis pathways. Key phytohormones, abscisic acid, indole-3 acetic acid, and sinapic acid were differentially accumulated in the seeds and are predicted to regulate dormancy in D. involucrata. We have provided extensive metabolic information useful for future works on dove tree germination study.

Effects of pretreatment, sowing time, sowing environment and climate factors on germination in Acer pseudoplatanus L.

In this study, the effects of different sowing environment (greenhouse and nursery), pretreatment (cold moist stratification), different sowing time (autumn, spring and summer) and some climate factors (air temperature, relative air humidity, soil temperature and soil moisture) on the germination of Acer pseudoplatanus L. seeds were studied. Seeds were harvested from the tree located in the Karadeniz Technical University campus. Three different germination trials were carried out; (1) direct sowing in autumn after seed collection (Control), (2) sowing stratified seeds in spring (Stratification-1) and (3) sowing stratified seeds in summer (Stratification-2). During the germination trial processes, air temperature, relative air humidity, soil temperature and soil moisture were measured periodicaly. Thus, the germination percentage changes in different sowing environments have been established on the basis of some climate factors. Higher germination percentages were obtained in the autumn (Control) compared to the spring (Stratification-1) and summer (Stratification-2) sowings. The highest percentages of germination were ­determined in the control trials (70% in greenhouse and 58% in nursery). Obtained germination results based on different sowing times revealed secondary dormancy in Acer pseudoplatanus L. seeds. It has been determined that the mean germination time in the greenhouse (12 days) was shorter than the mean germination time in the nursery (18 days). In addition, the obtained results showed that stratification and sowing time have a positive effect on the mean germination time in the greenhouse. Because of getting the best germination rates, keeping some climate ­factors constant (21.0-24.9 °C air temperature; 17.0-19.9 °C soil temperature; 63.0-68.9% relative air humidity; 60.0-67.9% soil moisture) during the vegetative propagation practices in the greenhouse, should affect mass ­seedling production in Acer pseudoplatanus L.

Effect of stratification and dipping with different concentrations of gibberellic acid in the vegetative and root growth characteristics of Pi-nus eldarica Medw.

This study was conducted on the seeds of Pinus eldarica during the period from February 2020 to September 2021 to find out the effect of cold stratification at (⁰4C) for (60 days) and different concentrations of gibberellic acid (0, 200,400 mg. L-1) in the traits of the vegetative and root growing seedlings. The results showed the superiority of the stratified seeds for the characteristics (seedling height, stem diameter, number of branches, number of leaves, root length, dry weight of the vegetative growth, dry weight of the root system). The results of dipping in gibberellic acid showed a superior concentration (400 mg.L-1) for traits (seedlings height, leaves number, length of the main root, dry weight of the shoot, dry weight of the root system). The concentration of 200 mg.L-1 for the two traits (stem diametet, branches number) was superior. The results of the binary interaction of stratification and gibberellic acid showed superiority of the stratified seeds with two concentrations (400 mg.L-1 and 200 mg.L-1) for traits (seedling height, eaves number, length of main root, dry weight of shoot, dry weight of root) and (Stems diameter Branches number) respectively.

Effects of temperature, moisture content and storage on dormancy release and germination of European hornbeam (Carpinus betulusL.) seeds

AbstractMature seeds of European hornbeam (Carpinus betulus L.) are characterized by deep physical and morphological dormancy. Although a procedure for their stratification is well developed, secondary dormancy prevents many healthy seeds from germinating, and this affects the productivity of the specie’s nursery material. The objective of this work was to determine optimal conditions for germination of European hornbeam seeds, and how to avoid the induction of their secondary dormancy. We also aimed at establishing methods for controlling the seed germination prior to sowing. Harvested nuts were stratified in a substrate at 20°/3°C for 4 + 16–18 weeks. Following stratification, the seeds were dried up to 25, 20, 15 and 10 per cent moisture content or frozen in the substrate at −3°C for 8, 16 or 32 weeks. The seeds dried up to 10 and 15 per cent moisture content were also stored at −3°C for 8, 16 and 32 weeks. After stratification, drying, storing and freezing, the seeds were germinated at the laboratory at 20°C and 3/20°C (16 + 8 h). However, reliable germination results were only achieved when the seeds not germinating at the above listed temperatures were additionally germinated at 3°C. Poor germination at 20° and 3/20°C was due to the induction of secondary dormancy. Stratified seeds of European hornbeam were found sensitive to dehydration. Their viability decreased considerably, particularly after drying up to 10 per cent moisture content, and in the seeds dried to 15 per cent the viability further decreased during storage. The seeds that were not dried but frozen at −3°C after stratification retained their germination ability for at least 16 weeks. Our results shows dual effects of temperature on germination control of hornbeam seeds. In laboratory practice applying temperature cycles of 3°/20°C at 16/8 h intervals is recommended to avoid the induction of secondary dormancy.

GIS-Facilitated Seed Germination and Multifaceted Evaluation of the Endangered Abies marocana Trab. (Pinaceae) Enabling Conservation and Sustainable Exploitation.

In the frame of the sustainable use of neglected and underutilized phytogenetic resources, and along with numerous studies in Abies spp. due to the innate conservation value of fir forests, this research focused on the Moroccan endemic fir, Abies marocana. The aim was triple-fold: to assess its potential and dynamics in economic sectors for sustainable exploitation; to determine the ecological conditions in which the species naturally thrives; and to find the appropriate requirements for its successful seed germination. We sourced multifaceted evaluations for three economic sectors performed in three levels, using 48 attributes and eight criteria from previous studies of our own, and the relevant species-specific assessments are overviewed herein in detail. The species’ ecological profile was constructed using Geographical Information Systems (GIS) and open access data (Worldclim). Seed germination trials were performed to examine the effect of cold stratification (non-stratified, one- and two-months stratified seeds), the influence of four temperatures (10 °C, 15 °C, 20 °C, and 25 °C), and interactions thereof in relation to germination percentage (GP) and mean germination time (MGT). The experiments showed that the interaction of cold stratification and germination temperature has a strong effect on the GP and MGT of A. marocana seeds. A detailed GIS-derived ecological profile of the focal species was created in terms of precipitation and temperature natural regimes, enabling the interpretation of the seed germination results. The multifaceted evaluations reveal an interesting potential of the Moroccan fir in different economic sectors, which is mainly compromised due to extant research gaps, unfavorable conditions, and low stakeholder attraction. The findings of this study fill in extant research gaps, contribute to in situ and ex situ conservation strategies, and can facilitate the sustainable exploitation of this emblematic local endemic plant of northern Morocco.

Key Metabolite Differences Between Korean Pine (Pinus koraiensis) Seeds With Primary Physiological Dormancy and No-Dormancy.

Pinus Koraiensis seeds have physiological dormancy. Cold stratification releases seed dormancy. The changes in metabolite profiles of dormant seeds and cold stratified seeds during shorter incubation time in a favorable condition for seed germination have been studied. However, a more-long-term detection of the changes in metabolites in dormant seeds can identify the real metabolic pathways responsible for dormancy. Metabolite composition was investigated in embryo and megagametophyte of primary physiological dormant seeds (DS) of P. Koraiensis collected at 0, 1, 2, 4, and 6 weeks of incubation and of non-primary physiological dormant seeds (NDS) sampled at 0 and 1 week of incubation, seed coat rupture stage, and radicle protrusion stage. Embryos contained higher levels of most metabolites than megagametophyte. Strong accumulation of most metabolites in DS occurred at 1 and 4 weeks of incubation. A larger reduction in the relative levels of most phosphorylated sugars and amino acids in NDS was found between 1-week-incubation and seed coat rupture stage. The relative levels of metabolites involved in carbohydrate metabolism, especially the pentose phosphate pathway (PPP) and tricarboxylic acid (TCA) cycle, were higher in the embryos of 4-week-incubated DS, but the relative contents of intermediate metabolites of most amino acid metabolism were lower compared to 1-week-incubated NDS. We suggested that the disturbed carbohydrate metabolism and amino acid metabolism in the embryos of DS after 4 weeks of incubation maybe related to primary dormancy. Our study provides information for a better understanding of the mechanism of seed dormancy.

Impact of seed cold stratification on apricot germination and subsequent seedling growth as well as chemical constituents of seeds during stratification

Freshly harvested seeds of apricot varieties "Balady (Amar)" and "Hamawy" were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. 5°C cold stratification was found to be the best for breaking seed dormancy, germination and seedling growth. Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds. Apricot seeds required a cold stratification of about 12-15 days for "Balady variety (Amar)" and15-18 days for "Hamawy" variety "to reach maximum germination and normal seedling growth. Chemical constituents of apricot seeds (total and reducing sugars, total free amino acids and total indoles were increased while that of free phenols and total soluble phenols were decreased) when stratification period prolonged. Therefore, it can be suggested that breaking of dormancy is coincided with several changes in different chemical constituents of seeds. Some of these materials increased and other materials which decreased at seed germinations.