Stratified Seeds Research Articles

Current and Predicted Future Winter Warm Spells Would Affect Douglas Fir (Pseudotsuga menziesii (Mirb.), Franco) Seeds in the Early Stage of Germination More Than in the Late Stage of Germination

Most tree species in the temperate climatic zone (including Douglas fir) disperse seeds in autumn. Some of them must be exposed to cold (0–10 °C) and moist conditions (cold stratification) to overcome dormancy and trigger germination. In the Northern Hemisphere, winter warm spells occur more frequently and last longer than in recent decades from eastern Canada to Europe. Our main research objective was to investigate the influence of current (1 or 3 days at day/night temperatures: 15 °C/10 °C) and future predicted (5 days at day/night temperatures: 25 °C/15 °C) winter warm spells on dormancy breaking and germination traits (germination energy—GE; germination capacity—GC; final germination capacity—FGC) of Douglas fir seeds from four old-growth stands in northern Poland. For this purpose, we interrupted cold stratification of seeds at different time points, i.e., after 3 weeks; 6 weeks; 9 or 3 weeks and 6 weeks; 3 and 9 weeks; 6 and 9 weeks; 3 and 6 weeks and 9 weeks. We found that for GE and GC, all main effects (populations—P; days of warm spell—D; stratification duration—W) and interactions were significant (except interaction P×D). FGC was significantly affected by the effects P and D and interactions of D × W and P × D × W. In addition, we found that the predicted warm spells negatively affected the early germination stage (GE and GC) of Douglas fir, but both current and future predicted winter conditions will not negatively affect the late germination stage (FGC).

Stratification as a way to increase germination of switchgrass seeds (Panicum virgatum L.)

Introduction. There is a practical interest in biofuels production from bioomass of perennial cereal grasses such as switchgrass, which is characterized by relatively high yields, low water and fertilization demand, reliable productivity in a wide geographical area, reduced soil erosion, carbon sequestration and improved wildlife habitat. The crop is propagated mainly by seeds, which is characterized by a long dormancy period, which leads to low field germination and uneven germination.
 Methods. Laboratory, visual, measuring and weighing, mathematical and statistical.
 Results. The main restraining factor in switchgrass widespread introduction into production and one of the ways to reduce the biological state of rest is stratification. Therefore, the aim of the research was to investigate the influence of seed stratification on the seed vigour and germination depending on the switchgrass varietal characteristics. The article presents the results of research on the seed stratification influence on its vigor and germination depending on varietal characteristics in order to reduce the biological dormancy of seeds and significantly increase germination. Determination of the response of different genotypes to stratification, the effect of low temperature on seed germination was carried out using seeds of four varieties of different groups of maturity: American origin varieties Foresburg — early, Cavein-rock — mid-late, Alamo — late and Ukrainian origin Morozko — midlate. Stratification, i. e. cooling seeds for 7 days at a temperature of 10◦C and germination at a temperature of 20◦C provided a significant increase in seed vigour and seed germination of all studied varieties. On average, the germination energy increased by 5% and germination by 4%. Seeds stratification differently affected seeds quality depending on varietal characteristics, while no natural changes in the seed quality by maturity groups were observed. It was found that stratification had a greater impact on germination energy, with the share of impact being 20%.
 Conclusions. Stratification provided a significant increase in seed vigour and germination in all studied varieties. On average, seed vigour increased by 5% and germination by 4%. But this measure does not provide a complete solution to reduce the biological state of seed dormancy.

Effect of Direct Sowing and Stratification on Germination and Growth of Peach under Sub-tropical Climate of Uttar Pradesh

Background: Availability of quality planting materials is the major impediment in extension of cultivation of low chilling peach in northern plans. Plum suckers are mostly used as rootstocks for raising peach; however nematode infestation is a major problem. Seeds of all peach cultivars do not germinate under subtropical climate of plains of Northern India. Hence, an experiment was carried out at ICAR-CISH, Lucknow on seed germination and subsequent growth of seedlings of low chilling peaches.Methods: Fully mature seeds of peach cv. Florda Prince, Pant Peach 1 and Sharbati were collected during June. Some of the seeds were sown direct in-situ during 1st week of December and remaining seeds were sown in the field after 2 months of stratification in the refrigerator at 7-8°C.Result: Stratification had significant effect on seed germination and late matured peach cv. ‘Sharbati’ exhibited higher seed germination. Good linear seedling growth and maximum percentage of buddable seedlings was found in stratified sown seeds of ‘Sharbati’ peach. Thus the study indicated that harvesting of ‘Sharbati’ and ‘Pant Peach-1’ seeds can be done during June and pre-sown stratification is necessary for better germination and growth of seedlings under subtropical climate of Lucknow.

THE CONTROL OF APRICOT SEED DORMANCY AND GERMINATION BY LOW TEMPERATURE TREATMENTS

Objective: Freshly harvested seeds of “Local” apricot variety were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C cold stratification (CS). 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.
 Methods: For stratification treatments, the seeds with removed endocarp were mixed with moistened sand. Afterward, they were subjected to a period of stratification at 5°C. Seeds were stratified in pots of 30 cm×40 cm. Stratified seeds were regularly irrigated once per week. To prevent the water loss during stratification upper surface of pots was covered by a sack. The following stratification was applied for apricot variety: CS for 0, 3, 6, 9, 12, and15 days in 1998 and 1999 years for “Local” variety.
 Results: Apricot seeds required a CS of about 15 days for “Local” variety to reach maximum germination and normal seedling growth. Moreover, when stratification period was prolonged, some of the chemical constituents of apricot seeds were increased and other was decreased. 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 (total, reducing and non-reducing sugars, total free amino acids, total indoles, and total and conjugated phenols) and other materials such as free phenols which decreased at seed germinations.
 Conclusion: The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C CS. 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.

Ontogenesis peculiarities to aboriginal Chechen shapes of willow-leaf pear under intensification of pear breeding process

The article presents the results of some experimental studies aimed at identifying the duration of the juvenile period that the aboriginal Chechen shapes of a willow-leaf pear have (PyrussalicifoliaPall.) under the acceleration of a breeding process, the goal of which is to achieve plants’ high early-maturity properties. The studies were carried out at Scientific Center “Gardens of Chechnya” within 2016–2019 in accordance with the Agreement on creative cooperation between All Russian Scientific Institute on Horticultural Crops Breeding and Scientific Center “Gardens of Chechnya”. The experiments were carried out in line with the Program for Breeding of Horticultural Crops, Berry and Walnut Fruits (1995) and the Program for Varieties-Study of Horticultural Crops, Berry and Walnut Fruits (1999). As a study object we used seeds of bred dwarf and weak-growing local Chechen shapes of the willow-leaf pear, generating fruit buds on one-year plants, and seeds of the Caucasian pear (PyruscaucasicaFed.) – 20500 pieces were taken of each shape. In April 2017, stratified seeds were sown in the sowing department of the Nursery Garden under the control of Gardens of Chechnya. Seedlings were grown according to generally accepted technology in rainfed conditions in a field with chestnut soil. Plants’ blossoming was observed in the spring of 2019. As an experiment result, based on a large amount of samplings, it was found that in rising plants among a great number of shapes of the aboriginal Chechen willow-leaf pear, the seedlings’ breeding is possible in the amount of a little more than 2 %, which have a very short juvenile period (2 years). The phenomenon is becoming an issue to study practically and scientifically with the aim to accelerate the breeding process and breed new varieties of pears with high early-maturity property. For further use and as source of a short juvenile period, 20 shapes of the willow-leaf pear were selected.

Bioinspired Optimization of Germination Nutrients Based on Lactuca sativa Seedling Root Traits as Influenced by Seed Stratification, Fortification and Light Spectrums

Ecophysiological stimulators directly affect root morphology, especially in the embryonic stage. To enhance crop germination, an understanding of the root traits under abiotic inducers is needed. In this study, the combined impacts of white and red-blue light spectrums, cold stratification, and seed fortification involving various concentrations of bioactive chemicals namely simple nutrient addition program solution, gibberellic acid, α-naphthaleneacetic acid with thiamine hydrochloride were evaluated on loose-leaf lettuce (Lactuca sativa var. Altima) seedling root architecture. The growth-promoting effects of these nutrients varied the growth rate and morphology of roots which are immediately shown during the radicle development. Integrated computer vision and computational intelligence were employed for phytomorphological signatures extraction of seedlings that were cultivated in a customized modulable spectrum experimental chamber (MSPEC). Root phenotype model was developed using graph-cut segmentation and region properties, and the ideal germination nutrient concentration was optimized using bioinspired models with firefly algorithm optimal result of 204.1 mg/L for nitrate, 238.15 mg/L for phosphate, and 158.08 mg/L for potassium. It was verified that lettuce seedlings can endure highly concentrated nutrients, however, it is more sensitive to phosphate as this macronutrient significantly promotes root growth with the increased whorl number on white light spectrum exposure with cold stratification.

Heteromericarpy of Heracleum sosnowskyi Manden. (Umbelliferae = Apiaceae)

Background. Heracleum sosnowskyi Manden. (family Umbelliferae = Apiaceae) is included in the lists of invasive species in many regions of Russia and European countries. Mericarps (fruits conventionally called seeds) of Heracleum L. spp. are characterized by an underdeveloped embryo and a complex morphophysiological type of dormancy; two-stage stratification is needed for their germination.Methods. In the period from 2014 to 2019, fruits of H. sosnowskyi were collected near settlements in Vyborg and Gatchina Districts, Leningrad Province; collecting was carried out from August through March. Seed size and 1000 seed weight were measured. Germination experiments were performed in the laboratory (22–24°C) monthly, from the time of collection in August until May. Seeds were germinated in Petri dishes on filter paper with three replications.Results. Large seeds on marginal umbellules of the central umbel were the largest in size. Their length was from 0.6 to 1.4 cm, width from 5 to 11 mm, and 1000 seed weight from 9 to 18 g. The length of smaller fruits was from 7 to 9 mm, width from 3 to 5 mm, and 1000 seed weight from 10.5 to 11.8 g. Germination of seeds collected in late summer was protracted. Under laboratory conditions, the emergence of the first seedlings was observed after 5–7 days. For the fruits stored in the laboratory, germination was reduced. Germination rate of stratified seeds varied from 55 to 99%.Conclusion. The biometric parameters of H. sosnowskyi mericarps were slightly affected by the place of growth and the year of maturation. Under laboratory conditions, H. sosnowskyi seeds collected in August showed germination rates from 3 to 15%. In years with a warm and long autumn, part of the fruit germinated in the year of maturation and managed to reach their juvenile state. Plump mericarps remained viable for at least three years. Sosnowsky’s hogweed fruits stored under laboratory conditions lost their germination ability within a year.

Seed productivity and reproduction features of Schisandra chinensis under conditions of the M.M. Gryshko National Botanical Garden

Data on seed productivity and peculiarities of reproduction of Schisandra chinensis under the conditions of introduction at the M.M. Gryshko National Botanical Garden of the National Academy of Sciences of Ukraine (NBG) are discussed. The study was carried out in 2016–2018 on experimental fields and in the NBG laboratory using plants and seeds of Ukrainian selection S. chinensis ‘Sadovyi-1’. Sections were examined with the microscope Carl Zeiss STEMI 2000-S. Qualitative and quantitative composition of higher fatty acids has been identified by НР-6890 chromatograph. It was found that S. chinensis of local reproduction have a much lower percentage of the seeds without embryo (about 10 %) compared to those of natural origin (30–90 %). Because of long-term storage of S. chinensis seeds the biochemical transformations take place: the content of fats and proteins decreased from 37.5 to 28.0 %, and from 19.7 to 11.2 %, respectively, the acid number of oil increased from 2.42 to 5.70 mg KOH/g, and its iodine value decreased from 32.5 to 30.3 g І2 / 100 g after storage of seeds during ten months. Fatty oil of S. chinensis seeds has a high linoleic acid content, which reaches 80–81.1 % of the total content of fatty acids. The storage of seeds under different illumination and temperature conditions resulted in minor changes in the acid number of the oil and the quantitative content of fatty acids. The optimal storage conditions of seeds (without access to light and at the temperature of +4 °С) were determined. Such storage conditions reduce the intensity of oxidative processes in the seeds, ensuring the highest germination rate. The optimal ways of S. chinensis reproduction by seeds are the spring sowing of stratified seeds and autumn sowing of freshly reaped seeds, which gain natural stratification. Using these ways resulted in 65 % and 63 % of seeds germination, respectively.

From Embryo to Adult: Low Temperatures Affect Phase Transitions of Allium sativum L. from Germination to Flowering

Juvenile and vegetative adult shoot apical meristems (SAM) are actively involved in acquisition of flowering competence, while the embryonic SAM is regarded as “responsible” only for germination. Comparative analyses of imbibed and stratified seeds of garlic Allium sativum show that only stratified seedlings produced bulbs and flower stems at the end of the season. Since the seed morphology of stratified and non-stratified seeds prior to sowing was similar, the differences are attributed to the molecular alterations in the embryonic SAM. Functional annotation analysis of 3000 differentially expressed genes suggests that seed imbibition reactivates the embryonic cell cycle, initiates the metabolism, and primes garlic seed germination. Stratification enhances DNA modifications, biosynthesis, cellular transport, and tissue development. Similar to vernalization of the vegetative buds, stratification of the embryonic SAM resulted in altered expression of meristem-identity and flowering homologs. Phase transitions from seed germination to flowering and bulbing in A. sativum are tightly connected, and possibly associated with downregulation of specific flowering repressor(s). The embryonic SAM plays an important role not only in seed germination, but in the entire plant life cycle, providing the foundation for the genetic regulation of major functional shifts in metabolism and development.

Peculiarities of the juvenile period of the native Chechen genotypes of willow leaf pear (Pyrus salicifolia Pall.)

The results of the study of the duration of the juvenile period of indigenous Chechen willow leaf pear genotypes (Pyrus salicifolia Pall.) are given in connection with the acceleration of the breeding process and the use of selected forms in pear breeding for high precocity. The studies were carried out in 2016-2019 at OOO “Orchards of Chechnya” in accordance with the Agreement on creative cooperation with the Russian Research Institute of Fruit Crop Breeding. The work was carried out in accordance with generally accepted programs and methods. The objects of the study were one-year and two-year-old pear seedlings obtained from sowing seeds of selected dwarf and low-growing local Chechen forms of willow pear (P. salicifolia Pall.), laying fruit buds on annual growths and seedlings of Caucasian pear (P. caucasica Fed.), 20 500 pcs. of each specie. The aim of the research was to study the potential of precocity of willow pear seedlings and to reveal of selected forms with the greatest degree of this trait. Stratified seeds were sown in the sowing department of the OOO “Orchards of Chechnya” production nursery in April, 2017. The seedlings were grown according to the common technology in dryland conditions on the plot with chestnut soil. The first fl owering of plants was noted in the spring, 2019. As a result of the research, for the first time on a large number of the experimental material it was found that in the off spring of the indigenous Chechen willow leaf pear genotypes, the selection of a little more than 2% of seedlings with a very short juvenile period (2 years) was possible. They are of great interest in accelerating the breeding process and in the selection of new pear varieties with high precocity. 20 willow leaf pear genotypes were selected for the further use in breeding for high precocity and as sources of the trait of short juvenile period.

Особливості репродуктивної здатності видів роду Juglans L. у колекційних насадженнях національного ботанічного саду імені М. М. Гришка НАН України

У 2016-2017 рр. визначено показники репродуктивної здатності видів роду Juglans L. Методи проведення досліджень: біолого-статистичні (візуальні спостереження та аналіз отриманих результатів), лабораторні (дослідження фертильності пилкових зерен). Виявлено, що частка фертильного пилку становила від 92,3 % (J. regia L. f. fertilis Petz et Kirch.) до 70,4 % (J. mandshurica Maxim.). Виявлено, що частка стерильного пилку найнижча у рослин J. regia L. f. fertilis Petz et Kirch. (7,6 %), вища – у рослин J. ailantifolia Carrière (35,1 %). З'ясовано, що показники реальної насіннєвої продуктивності видів роду Juglans L. найвищі у J. regia L. f. fertilis Petz et Kirch. (10,7), а найнижчі – у J. microcarpa Berland. (0,5). Встановлено, що середнє значення потенційної репродуктивної здатності найвище у J. regia L. f. fertilis Petz et Kirch. – (23,3), а найнижче – у J. microcarpa Berland. (1,6). Коефіцієнт продуктивності дослідних видів виявився найвищим у J. mandshurica Maxim. (80,1), а найнижчим – у J. major (Torr.) A. Heller (33,3). Найбільший врожай (6 балів) у дослідних рослин J. nigra L. зафіксовано у 2018 р., а найменший (2 бали) – у рослин J. microcarpa Berland. у 2017 р. Встановлено, що нежиттєздатного насіння дослідних видів в умовах інтродукції найбільше у J. regia L. f. fertilis Petz et Kirch. (3-2,7 %), а найменше – у J. mandshurica Maxim. (0,6-0,7 %). Виявлено, що стратифікація насіння видів роду Juglans L. в умовах інтродукції становить від 120 (60) (J. regia L. f. fertilis Petz et Kirch.) до 145 днів (J. nigra L., J. cinerea L.). Найкраща схожість насіння для більшості дослідних видів Juglans L. спостерігалась під час осіннього посіві в ґрунт з оплоднями – до 92 % (J. regia L.). Найгіршими виявились показники схожості насіння J. regia L. f. fertilis Petz et Kirch. (10 %). Дослідження показників репродуктивної здатності рослин роду Juglans L. показало, що отримані результати відрізняються між рослинами різних видів, проте види роду Juglans L. формують високу частку фертильного пилку – від 92,3 % (J. regia L. f. fertilis Petz et Kirch.) до 70,4 % (J. mandshurica Maxim.), щорічно плодоносять, формують виповнене схоже насіння, що говорить про адаптацію в умовах інтродукції.

Seed germination of Allochrusa gypsophiloides(Caryophyllaceae), an endemic species from Central Asia and Kazakhstan

The results of evaluating the laboratory seed germination of endemic Allochrusa gypsophiloides (Turkestan soap root), depending on storage conditions in combination with gibberellic acid treatment (GA3), are presented. In dry storage, control seeds were characterised by a long after-ripening period and a fluctuating germination behaviour upon removal from storage, with a maximum value of 23%. The sensitivity of seeds to GA3 during dry storage varied significantly, with two germination peaks at 5-7 months, and 12 months (37.5 and 50% germination, respectively). Cold stratification and cryo-preservation accelerated seed after-ripening, promoted germination synchronisation and increased seed sensitivity to GA3. The cold stratification of seeds increased germination four months earlier than during dry storage. GA3 increased germination from 16.7 and 18.3% for the control to 37.5 and 45% for seeds cryopreserved for 5 and 12 months, respectively. We recommend cryopreserving Turkestan soap root seeds to avoid viability loss and to then germinate the seeds after pretreatment with GA3.

Industrial residues as substrate components for the production of Ilex paraguariensis seedlings

Ilex paraguariensis is an important forest species in Brazil. Recently, the development of new products has increased seedlings demand and consequently, the interest in new products to use as substrates like residues from industries. We aimed to evaluate the viability of using industrial residues as substrates to produce yerba mate seedlings. We formulated thirteen substrates with coconut fiber, carbonized and decomposed yerba mate industrial residues in different ratios, which were compared to two commercial substrates, in a completely randomized design. The stratified seeds were placed in 110 cm³ tubes filled with the substrates. Plants were kept in a greenhouse for 135 days, shade house (70%) for 30 days, and rustification area in full sunlight for 15 days, under fertigation after 30 days of sowing. We evaluated montlhy the survival, height, and stem diameter, and at the end of the production period, we evaluated shoot and root dry mass. From the data obtained, we calculated the total dry mass and ‘Dickson quality index’. The substrates formulated with coconut fiber and decomposed yerba mate industrial residue can be used to produce yerba mate seedlings, but it depends on the ratio of the substrate components. Substrates with higher total porosity and microporosity provided seedlings with biometric characteristics similar to those produced in commercial substrates. The carbonized yerba mate residue reduced seedling growth when used in a percentage equal to or higher than 50% in the substrate.

Cold Stratification, Gibberellic Acid, and Priming Treatments to Promote Germination of <i>Lychnis wilfordii</i> (Regel) Maxim. Seeds

This study was carried out to indentify effective germination pretreatments for the mass propagation of Lychnis wilfordii. Seeds were treated with cold stratification (0, 4, 8, 12, and 16 weeks at 5°C), GA3 (0, 500, and 1000 mg･L-1), a nd priming t reatment (0.1 M and 0.2 M w ith NH4NO3, K2HPO4, KCl, and KNO3). All seeds were germinated at 2 5°C and 12 h photoperiod ( 40 μmol･m-2 ･s-1). GA3 treatment was also carried out in greenhouse. The highest final germination percentage (FGP) was 20.4% in 8-week-cold stratified seeds, whereas cold stratification for over 12 weeks decreased FGP of L. wilfordii. Seeds treated with 0, 500, and 1000 mg･L-1 GA3 showed germination percentages of 3.3, 4 4.0, a nd 6 2 .0% at 2 5°C in a g rowth chamber, a nd 5.3, 16.7, and 42% under greenhouse conditions, respectively. As the GA3 concentration increased, FGP increased. Furthermore, L. wilfordii seeds showed the highest FGP (54.7%) when primed with 0.2 M KNO3, but, MGT did not show any significant difference among treatments. Therefore we recommend soaking the seeds in 1000 mg･L-1 GA3 or 0.2 M-KNO3 p riming f or 2 4 h as a p roper treatment for effective seed germination in L. wilfordii.

Germination Traits in the Threatened Southeastern Grassland Endemic, Marshallia mohrii (Asteraceae)

Marshallia mohrii (Asteraceae) is a perennial forb endemic to grasslands in the southeastern United States. Despite having been listed as federally threatened for three decades, little is known about its biology and life history. In this study, we examined the role of light, temperature, seed age, and cold stratification on seed dormancy break and germination in M. mohrii. We also quantified soil temperatures in a Ketona glade population of M. mohrii to infer dormancy breaking and germination phenologies under natural conditions. Relatively high proportions (>65%) of cold stratified seeds germinated across a range of temperature regimes in both light and darkness, whereas nonstratified seeds only germinated to high proportions in light at high temperatures. Germination proportions of laboratory stored seeds were slightly greater than freshly matured seeds, but remained much lower than those of cold stratified seeds. According to laboratory experiments, both autumn and spring germination phenologies are possible depending on the temperature and light conditions seeds experience after dispersal. Seeds of M. mohrii exhibited type 3 non-deep conditional physiological dormancy, which has been found in other members of Asteraceae from temperate grasslands. Overall, the germination niche of M. mohrii is defined by conditional seed dormancy, reduced dormancy levels following cold stratification, dark germination after dormancy loss, seasonal germination cueing, and seed traits consistent with short-term persistence in soil. Results from our study are useful for future conservation and recovery actions with M. mohrii and represent the first known published report of germination traits in this genus, which contains several other rare and range-restricted species.

Effect of plant-derived smoke water and potassium nitrate on germination of understory boreal forest plants

This experiment assessed the effects of plant-derived smoke water, potassium nitrate (KNO3), and their combined effect on germination of cold-stratified and non-stratified seed from 18 native boreal forest plant species. Seeds were treated with smoke water diluted to 1:20, 0.1% KNO3, and smoke water + KNO3. Nine species responded positively to smoke water; these responses were dependent on the type of stratification, and three of these species only had a positive response to smoke water + KNO3 solution. Five species responded positively to KNO3 and four of those were associated with smoke water + KNO3 solution. Smoke water induced germination of several species, but only for seeds that had been previously cold-stratified. Vaccinium myrtilloides Michx. had the largest increase in germination using smoke water and the most reduced germination using KNO3. The interactions between smoke water, KNO3, and stratified seeds are not well understood. The effects and applications of smoke water and KNO3 (or other nitrogen sources) should be further researched to determine alternative approaches to restoration of disturbed boreal forest ecosystems.

Influence of different forms of iron on the morphobiological indicators of Pinus sylvestris

The wide distribution of iron in the environment of various forms of iron makes it relevant to study the characteristics of their influence on plant growth. In the present paper, the growth features of Pinus sylvestris – Scots pine were studied - during the cultivation of stratified seeds in a medium containing different forms of iron. It was established that the cultivation of pine seeds in a medium containing 0.1 M of iron in any form, inhibits the development of the root system. When cultivated in the environment containing iron nanoparticles at a concentration of 6.25 mmol / l, this led to a decrease in the root length to 3.71 ± 0.06 mm. On the contrary, the presence of iron nanoparticles in the medium for the cultivation of pine caused an increase in the length of the main and adventitious roots, as well as the number of adventitious roots. The content of iron microparticles in the medium for the cultivation of pine caused only a decrease in the length of the main root and adventitious roots. At the same time, at concentrations from 0.39 to 25 mmol / l, an increase in the number of adventitious roots occurred, which indicates compensatory reactions.

CULTIVATION OF MEDICINAL HERB HYPERICUM PERFORATUM IN THE LABORATORY CONDITION

This scientific article presents scientific data on the cultivation of medicinal herb Hypericum perforatum L. in the laboratory condition. In the laboratory condition, the rate of seed germination was much higher (75%-78%) when treated by thermal preparation compare to soaking seeds in water for a day and it was also observed the accelerating seed germination in the stratification with sand. Sowing seeds with treated solution (concentrated sulfuric acid) and stratification of seeds with sand were found to be able to grow faster, increase the number of foliage, relatively spreading of the root system and ready for field planting in the field conditions KEYWORDS: seedlings, seed, substrate, biohumus, stratification laboratory, Hypericum perforatum.

The temperature and length for the release of primary and induction of secondary physiological dormancy in Korean pine (Pinus koraiensis Sieb. et Zucc.) seeds

Primary physiological dormancy and secondary physiological dormancy of Korean pine seeds restrict the regeneration of broad-leaved Korean pine (Pinus koraiensis) mixed forest. Dry and imbibed seeds were stratified at 1 °C and 5 °C for 1, 2, 4 and 6 months. Germination percentage, mean germination time (MGT) and germination rate index (GRI) were measured to determine the optimal low temperature and its duration for the release of primary physiological dormancy. Once primary physiological dormancy was released through cold stratification, seeds were stored in an environment in which the temperature progressively increased from 5 to 25 °C. After one month of storage at each storage temperature, the germination percentage, MGT and GRI were measured to determine the threshold temperature for the induction of secondary physiological dormancy. Both dry and imbibed seeds not only exhibited a high germination percentage (approximately 80%) but also germinated rapidly (MGT and GRI were 17 days and 2.36, respectively) after 6 months of storage at either 1 °C or 5 °C. The germination percentage of cold stratified seeds gradually decreased from 78% (5 °C) to 72% (10 °C), 55% (15 °C), 10% (20 °C) and 8% (25 °C). The results of this study suggest that stratifying seeds at 1 °C or 5 °C for 6 months releases primary physiological dormancy. The induction of secondary physiological dormancy occurs at temperatures above 15 °C.

Alternative Splicing Regulation During Light-Induced Germination of Arabidopsis thaliana Seeds.

Seed dormancy and germination are relevant processes for a successful seedling establishment in the field. Light is one of the most important environmental factors involved in the relief of dormancy to promote seed germination. In Arabidopsis thaliana seeds, phytochrome photoreceptors tightly regulate gene expression at different levels. The contribution of alternative splicing (AS) regulation in the photocontrol of seed germination is still unknown. The aim of this work is to study gene expression modulated by light during germination of A. thaliana seeds, with focus on AS changes. Hence, we evaluated transcriptome-wide changes in stratified seeds irradiated with a pulse of red (Rp) or far-red (FRp) by RNA sequencing (RNA-seq). Our results show that the Rp changes the expression of ∼20% of the transcriptome and modifies the AS pattern of 226 genes associated with mRNA processing, RNA splicing, and mRNA metabolic processes. We further confirmed these effects for some of the affected AS events. Interestingly, the reverse transcriptase–polymerase chain reaction (RT–PCR) analyses show that the Rp modulates the AS of splicing-related factors (At-SR30, At-RS31a, At-RS31, and At-U2AF65A), a light-signaling component (At-PIF6), and a dormancy-related gene (At-DRM1). Furthermore, while the phytochrome B (phyB) is responsible for the AS pattern changes of At-U2AF65A and At-PIF6, the regulation of the other AS events is independent of this photoreceptor. We conclude that (i) Rp triggers AS changes in some splicing factors, light-signaling components, and dormancy/germination regulators; (ii) phyB modulates only some of these AS events; and (iii) AS events are regulated by R and FR light, but this regulation is not directly associated with the intensity of germination response. These data will help in boosting research in the splicing field and our understanding about the role of this mechanism during the photocontrol of seed germination.