Presence Of Dormancy Research Articles

Effect of dormancy on the emergence of Tabernaemontana heterophylla seedlings in different substrates

The composition and dynamics of plant communities are determined by the survival, dispersal and persistence of seeds in the soil, some of the fundamental aspects for understanding plant biology, among which seed dormancy is of particular importance. The aim of this work was to find out whether seed dormancy is affected by certain substrates in order to improve the production of Tabernaemontana heterophylla seedlings. Treatments were carried out with different substrates (T1. Sand, T2. Vegetable clay, T3. Vegetable clay + sand (1:1 ratio), T4. Vermiculite, T5. Cattle manure, T6. Sawdust and T7. Organic compost) in 7 x 4 factorial schemes, the results of which were subjected to an analysis of variance and a comparison of means with the Tukey test at a probability of 5%. The seeds with visible germination structure (hypocotyl) showed an apical meristem in a dormant stage. The number of normal seedlings did not exceed 25% of the germinated seeds in all treatments, with a high proportion of non-viable seeds observed. In the absence of technical information on overcome dormancy, it is important to use strategies that stimulate germination and subsequent seedling growth. The slow germination combined with the presence of dormancy in the hypocotyledon were factors that negatively affected the propagation of the species studied.

Dormancy in seeds of brazilian cerrado and dense Ombrophilous forest

The Cerrado and the Dense Ombrophilous Forest are important brazilian biomes that together cover more than half of the country's territory. They have a vast and rich plant diversity which often has a block in the germination process called dormancy. Dormancy can be defined as an obstruction in the germination of viable and intact seeds, even when all the favorable conditions are present. This work aimed to verify, through a literature survey, the occurrence of dormancy in seeds of plant species of the Brazilian Cerrado and Dense Ombrophilous Forest, comparing its occurrence between ecological groups of species, biomes and types of dormancy. The results showed that in Cerrado dormancy was observed in 56% of the species, whereas in Dense Ombrophilous Forest this number reduces to 42%. These data revealed an association between the presence of dormancy and the Cerrado. Also, in this biome, it was possible to verify a higher occurrence of physical dormancy in the seeds, with up to 63% of its dormant species presenting this type of dormancy. Pioneer species of Cerrado exhibited a greater dormancy percentage when comparing to climax, while this fact was not noticed in the forest, which resulted in an association between the ecological group of pioneer species from Cerrado and the dormancy process. These results show that dormancy may be related to more arid biomes and physical dormancy appears to be the most common type in these environments. Moreover, dormancy seems to be correlated with pioneer species of Cerrado, but not Forest

Dormancy in seeds of brazilian cerrado and dense Ombrophilous forest

The Cerrado and the Dense Ombrophilous Forest are important brazilian biomes that together cover more than half of the country's territory. They have a vast and rich plant diversity which often has a block in the germination process called dormancy. Dormancy can be defined as an obstruction in the germination of viable and intact seeds, even when all the favorable conditions are present. This work aimed to verify, through a literature survey, the occurrence of dormancy in seeds of plant species of the Brazilian Cerrado and Dense Ombrophilous Forest, comparing its occurrence between ecological groups of species, biomes and types of dormancy. The results showed that in Cerrado dormancy was observed in 56% of the species, whereas in Dense Ombrophilous Forest this number reduces to 42%. These data revealed an association between the presence of dormancy and the Cerrado. Also, in this biome, it was possible to verify a higher occurrence of physical dormancy in the seeds, with up to 63% of its dormant species presenting this type of dormancy. Pioneer species of Cerrado exhibited a greater dormancy percentage when comparing to climax, while this fact was not noticed in the forest, which resulted in an association between the ecological group of pioneer species from Cerrado and the dormancy process. These results show that dormancy may be related to more arid biomes and physical dormancy appears to be the most common type in these environments. Moreover, dormancy seems to be correlated with pioneer species of Cerrado, but not Forest

IMPORTANCE OF SEED QUALITY FOR THE FORESTRY SECTOR

Plant production is essential for the maintenance of human activity on Earth, and as seeds are the main tool for plant propagation, obtaining high-quality seeds is essential for successful planting. Forest species are applied in diff erent areas, such as timber, the pharmaceutical industry, landscaping projects, and degraded area recovery. The search for seedlings of forest species has increased due to the intense exploitation of ecosystems and the need to recover degraded areas. Therefore, it is necessary to use high-quality seeds that are composed of a complex set of attributes, including genetic, physical, physiological, and sanitary factors that directly infl uence the performance of seeds in the fi eld and their longevity in storage. Forest seeds have peculiarities, such as variable size and shape, nonuniform water content and germination speed, as well as diff erent drying and storage capacities. In addition, they have high genetic variability, which implies diffi culties in their management, such as the presence of dormancy, which can aff ect seed quality and seedling production. Seed germination and vigor are critical factors for the quality of forest seeds, but many species have not yet identifi ed their germination requirements. The lack of information about the peculiarities of each forest species and the high genetic variability among them makes it diffi cult to standardize methods for analyzing the physiological quality of seeds, in addition to becoming an obstacle to their use in reforestation projects, since the lack of diversity in the use of native species is a concern, as it reduces variety and endangers biodiversity

Seed dormancy and germination of native and invasive alien woody species of an endangered temperate forest in the Argentine Pampas

Forest restoration plans can benefit from knowledge of seed ecophysiology. Naturally, seeds respond to environmental clues to trigger germination or persist in the seed bank. Controlling dormancy and germination moment in native species will allow more efficient seed management, both for direct seeding (in situ restoration) and for native plant cultivation in nurseries (ex situ restoration). In addition, the differences in germination conditions of native and alien invasive trees can be used as control windows of the alien species in the seed bank. The aim of this study was to identify the environmental factors regulating seed dormancy and germination of native and alien trees of the Talares, an endangered temperate forest of the Argentine Pampas region. Seeds of the native trees Schinus longifolius, Jodina rhombifolia, Celtis tala and the alien trees, Ligustrum lucidum, Ligustrum sinense and Gleditsia triacanthos were collected and the presence of dormancy was determined exposing the seeds to standard germination protocols. In case of dormancy presence, a post-maturation experiment was carried out in two conditions: i) cold and wet (stratification) and ii) dry and warm (after-ripening). The native species J. rhombifolia and C. tala showed seed dormancy but S. longifolius did not. For C. tala germination it was necessary a previous post-maturing process; however, environmental conditions for J. rhombifolia germination were not attained. Alien species showed a high germination, reaching up to 100% in at least one of the evaluated conditions, and displayed different emergence windows compare to natives. Since alien species germinated at lower temperatures than natives, a temporal window for chemical or mechanical control is proposed. Ecophysiology of seed dormancy and germination facilitates strategies for decision makers, as it can make native seeds use and aliens control more efficient to meet global restoration goals.

Reference values for germination and emergence measurements

Why should we care about reference values for germination and emergence measurements? Because they can help in the conservation of species and thus the recovery or restoration of altered areas. Therefore, for the first time, we evaluated the germination and emergence processes of diaspores of five Cerrado species to propose reference values for the germination and emergence measurements to enable species comparison, and consequently, facilitate better conservation decisions. The five species have diaspores with high physiological quality and intraspecific variability in relation to most of the germination and emergence measurements, showing that they still retain their reproductive potential. The processes of seed germination and seedling emergence in Anadenanthera colubrina (Vell.) Brenan and Ceiba speciosa (A.St.-Hil.) Ravenna and seedling emergence in Astronium urundeuva Engl. were faster and more synchronised than those of Cedrela fissilis Vell. (emergence) and Lithraea molleoides (Vell.) Engl. (germination and emergence), indicating the presence of dormancy in the diaspores of the last two species. However, considering the reference values determined here, all the species could be considered very slow and very asynchronous. This means that all the species use large environmental windows to establish themselves, where the spreading of seed germination and seedling emergence over time is an important survival advantage.

Germination of Pulsatilla cernua var. koreana Seeds as Influenced by Harvest Dates and Development of Seeds Analyzed by X-ray Imaging

Pulsatilla cernua var. koreana seeds were harvested at six different dates between 16 days after flowering (DAF) (8 Apr.) and 43 DAF (5 May) in 2018 and categorized into six groups based on X-ray images. Germination tests were performed without and with 2 weeks of moist 5 °C treatment [cold stratification (CS)]. Seeds harvested at 38 DAF (30 Apr.) with well-developed vegetative organs (embryo and endosperm) in seeds categorized as A and B (seed A and seed B, respectively) based on the X-ray images were considered fully developed, and 80% of seeds were considered mature. However, the germination rates were less than 26% or 28% when full seeds harvested at 43 DAF received no or 14 days of CS treatment, respectively. Our study suggests that the low germination rate of fully developed seeds as judged by X-ray images showing well-developed embryo and endosperm could result from the presence of dormancy that was not broken effectively by 14 days of CS coupled with the loss of viability caused by 8 months of dry storage at 5 °C.

Techniques for breaking seed dormancy of rainforest species from genus Acronychia

We tested for dormancy in three species of Acronychia (Rutaceae) occurring in the rainforest in eastern Australia, A. imperforata, A. laevis and A. oblongifolia, by incubating fresh intact seeds on 0.8% water agar for one month at 25/10°C. Four different techniques were then tested for their effect on dormancy: (i) incubation of intact seeds on agar incorporating gibberellic acid (GA3); (ii) seed coat removal (decoating); (iii) scarification near the radicle emergence point (scarification-emergence point); and (iv) scarification opposite the radicle emergence point (scarification-back). Imbibition tests were performed to determine whether dormancy was due to an impermeable seed coat. Germination differed among treatments, but all three species showed a similar pattern. Intact seeds showed < 6% germination after one month indicating the presence of dormancy. Highest germination (> 65%) was observed following scarification-emergence point treatment. Seed coat removal also resulted in increased germination (40-47%), in comparison with intact seeds, but GA3 and scarification-back treatments did not (< 12%). Though the seedcoats of all species were permeable, increased germination responses to decoating and scarification-emergence point treatments suggest scarification is required to clear the radicle emergence point. This may be a useful dormancy-breaking technique for Acronychia spp. and may be suitable for related Rutaceae species.

Dormancy overcoming in seeds of cajá-manga (Spondias dulcis)

The propagation of ‘cajá-manga’ (Spondias dulcis) is usually performed by seeds. The presence of dormancy is an obstacle for seedling production and the commercial use of its main product, the fruit. This research aimed to evaluate the use of phytoregulators associated with the scarification of the distal region of the embryo in dormancy overcoming and in the standardization of germination of ‘cajá-manga’ seedlings. Endocarps extracted from fruits of six matrices were subjected to the following treatments: control (T1), mechanic scarification in the distal region of the embryonic axis (T2); all following treatments involved scarification and imbibition in a solution of: water for 6h (T3); GA3 (750 mgL-1) for 6h (T4); GA3 (350 mg L-1) for 12h (T5); Cytokinin (750 mg L-1) for 6h (T6); Cytokinin (350 mg L-1) for 12h (T7); GA3 and Cytokinin (750 mg L-1) for 6h (T8); and GA3 and Cytokinin sowing 25 endocarps in expanded polystyrene trays using a washed sand substrate. The following variables were evaluated: emergence, first emergence count, emergence speed index, mean emergence time, shoot and root length of seedlings, and relative emergence frequency. The experimental design was in randomized blocks, with 9 treatments and four replications consisting of 25 endocarps each. The data obtained were subjected to the F Test at a 1% level of probability, as well as to the Scott-Knott method. The use of mechanic scarification in the opposite region of the embryonic axis, followed by the imbibition in a solution of gibberellin + cytokinin at the concentration of 350 mgL-1 for 12 hours is promising for dormancy overcoming in seeds of Spondias dulcis.

Germination of Pulsatilla Seeds as Influenced by Seed Morphology, Moist 5 °C and Gibberellin (GA3) Treatment, and Detection of Nickel in Seeds

Seeds of Pulsatilla turczaninovii were categorized to full and empty seeds based on observations under a light microscope and on X-ray images. A germination test for full or empty seeds was evaluated as affected by the duration of gibberellin GA3 and the moist 5 °C cold stratification (CS) treatment. The morphological and elemental components of P. turczaninovii and P. cernua var. koreana seeds were analyzed using low-temperature scanning electron microscopy (LT-SEM) and energy dispersive X-ray diffraction analysis. The results showed that 64% of full and semifull P. turczaninovii seeds 10 weeks after harvesting germinated in 17 to 19 days; however, the germination rate, including empty and semiempty seeds, was lower (52.6%). Full seeds with damaged or dried vegetative organs (embryo or endosperm) and semifull seeds with severely damaged vegetative organs were observed, and this result could be related to low germination rates. Germination patterns of seeds stored dry at 5 °C for 44 weeks that showed a sigmoid pattern were increased by immersing seeds in a GA3 solution for 8 hours and treating seeds with 16 or 32 days of CS. More seeds germinated between 12 and 17 days (as compared with 17 to 29 days), especially when they were treated with GA3 and received 32 days of CS. Comparison of germination rates of visually full seeds upon harvest (52.6%) with those that had been stored dry for 44 weeks (26.3% to 29.7%) suggested that the viability of seeds may have decreased. Dormancy could be a factor that decreased germination and can be removed by low temperature and GA3 treatment. LT-SEM revealed a valley-like, sunken streak in empty seeds of P. cernua var. koreana. The nickel content in the trichome and seedcoat of full and empty seeds of both taxa ranged from 2.98 to 4.62 (weight %), as determined on X-ray images. Our study suggested that the low germination rate was due to either the presence of dormancy, damage to either embryo or endosperm, a loss in viability, or the presence of nickel in the seeds.

Effects of temperature on germination in eight Western Australian herbaceous species

Germination is a high-risk phase in a plant’s life cycle and is directly regulated by temperature. Seeds germinate over a range of temperatures within which there is an optimum temperature, with thresholds above and below which no germination occurs. Rapid changes in temperature associated with global warming may cause a disconnect between temperatures a seed experiences and temperatures over which germination can occur. This paper explores the temperature dimension of the germination niche of eight herbaceous species from South West Western Australia as part of a broader assessment of endemic native species at risk of decline under global warming. The data obtained from germination studies on a temperature gradient plate were used to populate models to predict optimum germination responses (mean time to germination, germination timing and success) under current (1950–2000 averages) and future (2070 high greenhouse gas emission) temperature scenarios. The species exhibited a mix of germination responses, often with high tolerance to high diurnal temperatures. A number of species did not reach their full potential within the experimental period, indicating the presence of dormancy not overcome due to temperature alone. Modelling revealed that for some species the opportunity for germination may decline due to rising temperatures, but for others there would be little change, though a shift in germination timing may be expected. This approach to identifying extinction risk contributes tangibly to efforts to predict plant responses to environmental change and can help prioritize species for management actions, direct limited resources towards further investigations and supplement bioclimatic modelling.

Evaluación de viabilidad de semillas de 17 especies tropicales altoandinas por la prueba de germinación y la prueba de tetrazolio

La viabilidad denota el potencial que tiene una semilla para germinar, la cual está ligada al éxito o fracaso reproductivo de las poblaciones y de esta manera es una de las primeras variables a evaluar cuando se trabaja con semillas. Nuestro objetivo fue determinar el mejor método para evaluar la viabilidad en 17 especies altoandinas; se comparó la viabilidad mediante dos pruebas: Tetrazolio, para la cual se probaron variaciones de concentración, acondicionamiento y tiempo de exposición; y germinación, que se trabajó bajo condiciones controladas a 20/10 °C, fotoperiodo y termoperiodo de 12 horas. Se utilizó la prueba Kruskal- Wallis para evaluar diferencias. Se encontraron diferencias en el valor de viabilidad entre las pruebas. En 11 especies se recomienda la prueba de Tetrazolio, donde la mejor condición de evaluación fue [1-1,5 %] TZ, 40 °C y 24 horas de exposición. En Puya, Hypericum y Gaultheria la prueba de germinación fue mejor para evaluar la viabilidad. La comparación de las pruebas permitió detectar la presencia de dormancia en algunas especies donde se evidenció una alta viabilidad pero baja germinación. Los resultados permitieron determinar el método más confiable para evaluar la viabilidad en las diferentes especies, aportar información sobre sus requerimientos germinativos y potencial para la propagación sexual, así como detectar la posible presencia de dormancia y la necesidad de profundizar en la evaluación de los métodos de ruptura que permitan aumentar los porcentajes de germinación en algunas de las especies.

Alternative treatment to stimulate the germination of recently harvested wheat seeds

Abstract: The germination test for recently harvested wheat seeds requires a period of up to 20 days, because of the presence of dormancy. The possibility of reducing this period provides greater speed to the allocation of seeds, as well as an increased operational capacity of analytical laboratories. This study aimed at evaluating the effectiveness of treatments to stimulate the germination of recently harvested wheat seeds, reducing the five-day pre-cheeling period recommended to run the test. Seeds from various wheat genotypes were used: BRS Guamirim, BRS Tangará, BRS Pardela, CD 108, CD 116, CD 150, IPR Catuara TM, Frontana, IPR Taquari, Safira and Quartzo. They were analyzed immediately after collection and then stored for 30 and 180 days. In each evaluation period (immediately after harvesting, 30 and 180 days of storage), the determination of water content, the germination test (seeds without pre-chilling and pre-chilling between 5 and 10 ° C for three to five days), and also the tetrazolium test to quantify viability and seed dormancy were carried out. Based on these results, it is concluded that there is effectiveness in overcoming wheat seed dormancy, adopting the pre-cheeling procedure between 5 and 10 ° C for three days.

Metagenomic analysis of buffalo rumen microbiome: Effect of roughage diet on Dormancy and Sporulation genes

Buffalo rumen microbiome experiences a variety of diet stress and represents reservoir of Dormancy and Sporulation genes. However, the information on genomic responses to such conditions is very limited. The Ion Torrent PGM next generation sequencing technology was used to characterize general microbial diversity and the repertoire of microbial genes present, including genes associated with Dormancy and Sporulation in Mehsani buffalo rumen metagenome. The research findings revealed the abundance of bacteria at the domain level and presence of Dormancy and Sporulation genes which were predominantly associated with the Clostridia and Bacilli taxa belonging to the phyla Firmicutes. Genes associated with Sporulation cluster and Sporulation orphans were increased from 50% to 100% roughage treatment, thereby promoting sporulation all along the treatments. The spore germination is observed to be the highest in the 75% roughage treatment both in the liquid and solid rumen fraction samples with respect to the decrease in the values of the genes associated with spore core dehydration, thereby facilitating spore core hydration which is necessary for spore germination.

Comportamento germinativo de <I>Sophora tomentosa</I> L. (Fabaceae: Faboideae) de três populações DOI:10.5007/2178-4574.2011n40p82

abaceae is an important botanical family with a large number of species with dormant seeds. The aim of this study was to determine the presence or absence of dormancy in seeds of Sophora tomentosa. Seeds were collected in Florianópolis, SC, on the beachs of Daniela, Campeche and Ingleses, and germinated in boxes transparent, with 200ml of washed and autoclaved sand, in germination chambers at temperatures of 20°C, 30°C and alternating of 30/20°C (photoperiod of 12 hours). The alternating temperature not improve germination (13%) compared to constant temperatures of 20ºC (9%) and 30ºC (13%). Seeds from Ingleses and Campeche showed a high germination, above 70% for alternating temperatures and constant temperatures of 30°C and 20°C (79%). For seeds from Ingleses it was found significant difference between germination at 30°C and alternating temperature related to germination at 20°C. It was concluded that there was dormancy only for seeds from Daniela. The presence of dormancy in seeds form Daniela can be related to the time of seeds were picked up, in the winter in the case of seeds from Daniela, and in the summer in the case of seeds from Campeche and Ingleses. The storage of for 6 months for seeds from Daniela could also provoke dormancy.

Morphogenetic analysis of the phenotypic variability of the architectural unit of Hydrangea macrophylla

• Hydrangea macrophylla is a ligneous plant that has attracted the attention of many plant breeders and agronomists for the purpose of enhancing its phenotypic plasticity. However, this plasticity was always exploited empirically.• Can this plasticity be assessed by a more scientific approach? In this work, the phenotypic variation is analysed via a description of the different development sequences of the plant and by exposing the plant to different contrasted environments.• The architectural unit consists of two morphogenetic units: the Vegetative Unit (VU) and the Vegetative and Floral Unit (VFU). They result in four successive development sequences: an organogenetic phase accompanied by continuous growth (sequence A), floral transformation (sequence B), dormancy (sequence C) and flower bloom (sequence D). Under the effect of environmental factors, the formation of the mixed terminal bud (sequence B) provides a considerable source of spatial variability, whereas the absence or presence of dormancy (sequence C) is responsible for a source of temporal variation.• The in-depth description of the architectural unit with its morphological components and the characterisation of the four development sequences provide a necessary scientific basis to identify environmental effects on plant development and for the integrated use of its plasticity.

The identification and exploitation of dormancy in genetic programming

In genetic programming, introns--fragments of code which do not contribute to the fitness of individuals--are usually viewed negatively, and much research has been undertaken into ways of minimising their occurrence or effects. However, identification and removal of introns is often computationally expensive and sometimes intractable. We have therefore focused our attention on one particular class of intron, which we refer to as dormant nodes. Mechanisms for locating such nodes are cheap to implement, and reveal that the presence of dormancy can be extensive. Once identified, dormancy can be exploited in at least three ways: improving execution efficiency, improving solution-finding performance, and simplifying program code. Experimentation shows that the gains to be had in all three cases can be significant.

A study of the germination responses of a Sardinian population of sea fennel (Crithmum maritimum)

Germination tests have been carried out on seeds of a Mediterranean population of sea fennel (Crithmum maritimum L.) collected from plants in Santa Margherita di Pula, in the southwest of Sardinia, Italy. Germination was evaluated in the dark at different temperatures and at various salt concentrations. The optimal conditions for germination were a constant 20 °C in deionized water or at a very low salt concentration. These conditions are strikingly different from those necessary for the germination of seeds from the Atlantic coast (Meadfoot Bay, England). The presence of dormancy in the seeds is analyzed and discussed in terms of ecophysiological control and mechanisms which prevent germination under adverse environmental conditions.