Non-scarified Seeds Research Articles

Mechanical scarification increases seed germination of Neltuma alba (Fabaceae), a threatened tree from the Atacama Desert

Neltuma alba is a tree whose seeds were probably dispersed by now-extinct animals. Currently, its fruits are consumed by foxes, guanacos, donkeys, and goats, which may scarify the seeds during ingestion, thereby enhancing germination. However, these animals might damage the cotyledons when chewing the fruits, potentially reducing the survival and growth of the plants, although this occurs infrequently. We hypothesize that mechanical scarification of seeds increases their germination but does not affect the survival and growth of the plants. Our objective was to evaluate the effects of mechanical scarification on seed germination and subsequent plant survival. We scarified the seeds by sanding them before sowing them in a nursery with daily watering for six months. Subsequently, the plants were transplanted to the field, where they received daily watering for six months, biweekly watering for the next twelve months, and no watering for the following two years. Seed scarification significantly increased germination by 1.5 times: 58 and 39% germination in scarified and non-scarified seeds, respectively. Scarification did not significantly affect plant survival. Survival rates were 93, 67, 67, and 26% at the end of the first, second, third, and fourth years, respectively. Similarly, scarification did not significantly affect plant height, with plants reaching heights of 28, 59, 74, and 118 cm in the first, second, third, and fourth years, respectively. Understanding the limiting factors for the reproduction of endangered plants in the Atacama Desert is crucial for proposing effective conservation actions.

Biometric aspects of fruits and seeds and determination of the absorption curve of Hymenaea martiana Hayne seeds.

The biometric differences between fruits and seeds are useful characteristics that can provide important data for the investigation and preservation of the species and may be linked to environmental and genetic influences. In this sense, considering the importance of this species and the need for conservation, the objective was to carry out physical characterization of the fruits and seeds of Hymenaea martiana as well as to determine the seed imbibition curve. The experiment was conducted at the Seed Analysis Laboratory at the Agricultural Sciences Center at the Federal University of Paraíba in Areia, PB. The evaluations carried out were as follows: biometry of fruits and seeds, number of seeds per fruit, colorimetry of fruits and seeds, percentage of damaged seeds, weight of a thousand seeds, seed water content, mass and imbibition curve. The biometric data were subjected to descriptive analysis to determine the minimum, maximum, average value, standard deviation, asymmetry, and kurtosis of the fruits and seeds. In terms of the biometric characteristics of the fruits and seeds of H. martiana, there was a marked variation, with average fruit lengths of 90.28 mm, widths of 46.83 mm, thicknesses of 34.69 mm, weights of 65.86 g and four seeds per fruit. The average length, width, thickness and weight of the seeds were 23.75 mm, 18.34 mm, 12.71 g and 4.13 g, respectively. The fruits were darker than the seeds, and both the fruits and seeds had red tones. Compared with nonscarified seeds, scarified seeds absorb a greater amount of water.

Dormancy and Light Requirement for Germination of Sprawling Bauhinia (Tylosemafassoglense) Seeds

<em>Tylosemafassoglense</em> (Fabaceae) is a tuber producing vine, endemic to sub-Saharan Africa, where it's used as food, fodder and medicine. However, its domestication may be hampered by limited information on its seed dormancy and germination ecology. This study evaluated seed-coat dormancy on three seed lots, collected from Busia, Migori and Siaya counties in Kenya, and the role of light on germination. Seed-coat dormancy was studied by water imbibition and germination percentage at 25℃ on scarified and non-scarified seeds from each seed lot.

In Vitro Studies on Seed Germination of the Mediterranean Species Anthyllis barba-jovis to Facilitate Its Introduction into the Floriculture Industry

Anthyllis barba-jovis is a salt and drought tolerant evergreen shrub, native of the western-central Mediterranean coasts, with ornamental characteristics that make it worthy to be exploited for commercial use as an ornamental and landscape plant. Therefore, the present study aimed to determine germination as affected by seed-coat, temperature, photoperiod, and seed storage period, as a first approach to introduce the species into the floriculture industry. Seeds scarified or non-scarified, recently harvested or after storage at room temperature in the dark for 12, 24, or 36 months were placed for germination in vitro on Murashige and Skoog (MS) medium, under 16 h photoperiod (LD) or continuous darkness, at 5–35 °C, at 5 °C intervals. Seed pre-treatment by mechanical scarification with sandpaper highly promoted their germinability. Seeds germinated in all treatments at varying percentages. Photoperiod had no significant effect on germination. Cardinal temperatures for germination were defined at 35 °C and 5 °C (possibly even lower, particularly for up to 1-year-old seeds, which germinated at 30–58% at 5 °C when scarified). Temperatures from 15 to 25 °C were optimal for germination of recently harvested or 1-year-old seeds (82–98% when scarified), whereas older seeds germinated at higher percentages at 20 °C (65–97% when scarified), thus long storage affected both the range of optimal temperatures for germination and the germination percentage. Storage reduced germination mostly of non-scarified seeds. Three years after harvesting A. barba-jovis seeds germinated at high percentages (77%) at 20 °C and LD when scarified, while without scarification germination was less than 10% in all treatments.

Kinetics of Imbibition and Light Quality in Echinocactus Platyacanthus LK &amp; O Germination

Given that germination is a crucial stage in the development of plants, it is essential to carry out studies on the factors that affect this phase. The optimal conditions for each species should also be defined, especially those that, by their nature, present such problems in their propagation and conservation that render them vulnerable. Many species of the cacti family belong to this group, so this research aims to contribute to the knowledge of some factors that impact the germination of Echinocactus platyacanthus. The first purpose of this work was to describe the kinetics of scarified seeds imbibition at 25, 30, and 35°C and their impact on the germination response. The evaluation of the effects of red light on the germinative response was established as a second purpose. The results showed that the imbibition process in scarified seeds fits a curve of the Weibull model, with 15.03, 15.62, and 18.84 hours α coefficients, and 0.08, 0.09, and 0.45 β coefficients for temperatures of 25, 30, and 35°C, respectively. In non-scarified seeds, the coefficients were 10.85, 13.11, and 13.06 hours α, and 0.12, 0.10, and 0.08 β for temperatures of 25, 30, and 35°C, respectively. Scarification and temperature favor rapid water uptake. The imbibition behavior is similar under both conditions, unlike the final germination percentage. Temperature influences the imbibition percentage and favors germination since the temperature of 35°C registered over 90%. The seeds irradiated with red light recorded 96% germination at 144 and 168 hours, confirming that light quality influences this response. A possible physical latency and mechanical dormancy are ruled out, demonstrating positive photodormancy. Key words: photodormancy, cactus, red light, scarification, germination

Seeds of the threatened dry rainforest tree Cadellia pentastylis (Surianaceae) are non-dormant

AbstractCadellia pentastylis (Surianaceae) is an Australian endemic threatened rainforest tree. Irregular flowering and fruiting events coupled with high rates of infertility and insect predation has meant that seed testing has not been possible for this species. Seeds were opportunistically collected from a wild population in early 2021, which allowed for the first germination tests to be conducted. In this study, the presence of physical dormancy was examined by performing an imbibition test using scarified and non-scarified seeds. We also investigated whether a 5-min heat shock treatment at temperatures ranging from 60 to 120°C improved germination success. The presence of physiological dormancy was also examined by recording germination success following a gibberellic acid or smoke-water pre-treatment. Both scarified and non-scarified seeds readily imbibed water over a 72-h period, and several seeds had germinated in both treatments after 48 h. Final germination proportion and t50 following a heat shock, gibberellic acid or smoke-water pre-treatment did not significantly differ from the controls. We conclude that C. pentastylis seeds are non-dormant. Although a palisade cell layer has been reported in the endocarp, our results suggest that this layer may not be sufficiently formed to restrict germination. We recommend that seeds are collected from populations following dispersal and propagated shortly after or stored as conservation collections in ex situ Seedbanks.

Seed Germination Ecophysiology of Acacia dealbata Link and Acacia mearnsii De Wild.: Two Invasive Species in the Mediterranean Basin

Acacia dealbata and A. mearnsii are two invasive species found in coastal, mountain, and riparian Mediterranean habitats. Seed biology and germination traits are important drivers of the competitive performance of plants and may significantly contribute to biological invasions. The seeds of Acacia s.l. have physical dormancy due to an impermeable epidermal layer. The aim of this study was to assess the germination capacity of scarified and non-scarified seeds of A. dealbata and A. mearnsii from different areas of the Mediterranean Basin. To test the seed imbibition capacity, the increase in mass was evaluated. Non-scarified seeds were tested at 15, 20, and 25 °C in light conditions. Scarified seeds were tested at 5, 10, 15, 20, and 25 °C and 25/10 °C in light and dark conditions. Scarified seeds increased in mass more than non-scarified seeds. Both species showed a higher germination capacity at 25 °C in non-scarified seeds; A. dealbata reached a germination maximum of 55%, while A. mearnsii reached 40%, showing a difference among these populations. Scarified seeds of both species reached germination percentages &gt;95% at all temperatures except at 5 °C in dark conditions. Scarification was necessary to break dormancy and promote germination. The present study provides new knowledge about the seed ecology and germinative behaviour of the two Acacia species under different pre-treatment, temperature, and photoperiod regimes, contributing to the understanding of their invasive behaviour.

Dormancy, viability and germination of Magnolia lanuginosa (Wall.) Figlar & Noot. seeds: A threatened tree species of Northeast India

The population of Magnolia lanuginosa a rare tree species of northeastern India has declined drastically owing to habitat destruction, low natural regeneration and over harvesting for its multipurpose uses. The present study was carried out to understand the type of dormancy and analyse the effect of storage on viability and germination behaviour of M. lanuginosa under various physical and chemical treatments. Seeds subjected to physical treatments such as water (cold, hot, and boiling), acid (H2SO4) and manual scarification failed in breaking dormancy. Seeds treated with growth regulators (GA3) had a significant effect on germination. It reduced the germination time and the shortest T50 was observed in seeds treated with 2000 mg/l of GA3 (non-scarified seeds) and 1000 mg/l of GA3 (scarified seeds). The use of KNO3 did not have any significant effect in breaking dormancy. However, the use of KNO3 along with GA3, increased the germination percentage. Seeds cold stratified (CS) for 60 days at 5 °C was effective in breaking dormancy and resulted in 84.26% germination. This indicates the prevalence of Type-1 Non deep physiological dormancy in M. lanuginosa seeds that requires a crucial CS period for proper embryo growth and development. The seeds stored in moist sand at 5 °C remained viable even after 120 days with 48.88% viability. The study would be helpful in devising seed germination protocols for mass production and reintroduction of the species into the wild.

Agrobiological methods of increase in germinating capacity of seeds of perennial legume grasses in the Middle Preduralie

The article presents the results of laboratory research of swelling rate of non-traditional for the region perennial crops: Gelega orientalis, Poterium polygamum in comparison with traditional Medicago varia Mart. Investigation of watering and swelling process was carried out by gravimetric method. Positive effect of scarification on the rate of water consumption of Galega orientalis and Medicago varia Mart is confirmed: swelling rate of Galega orientalis increased from 0.14 1/h up to 1.09 l/h, Medicago varia Mart – from 0.24 l/h up to 1.85 l/h, which is seven times more than the swelling rate of non-scarified seeds. The swelling rate of scarified seeds of Poterium polygamum conversely decreased from 1.69 l/h to 0.74 l/h. Laboratory seed germination of Galega orientalis and Medicago varia Mart with seed scarification and soaking up to 60% of water level increased threefold relative to the control variant without scarification and twofold to the control variant with scarification. Negative effect on biometric parameters of Galega orientalis and Medicago varia Mart seedlings was noted when seeds were soaked up to 100% of water level. Laboratory germination of Poterium polygamum in all experimental variants was equal to 96%. However, parameters of seedlings were different regarding experimental factors, thus biometric parameters of seedlings increased with the raise of water level in non-scarified seeds of Poterium polygamum and decreased in scarified ones.

Response of Flamboyant seeds (Delonix regia) subjected to different dormancy overcoming methods

Flamboyant has great ornamental use, because it has beautiful flowers, having a great use in urban afforestation and park ornamentation. The seeds have a low germination rate because they have dormancy caused by the impermeability of the integument. In this sense, the objective was to determine the most efficient method to overcome dormancy in flamboyant seeds. The experimental design was fully randomized with 4 treatments and 3 replications. The treatments consisted of: 1-Witness (non-scarified seeds); 2- Hot water at 90º C for 5 minutes; 3- Concentrated sulfuric acid 98% for 60 minutes; 4- Mechanical scarification with sandpaper number 80. The characteristics evaluated were: emergency, emergency speed index, seedling height and root length. A significant difference can be observed in the treatments evaluated only for the emergency speed index where the scarification treatment with sandpaper was higher than the others, for the other characteristics evaluated there was no difference

Do scarification and seed soaking periods promote maximum vigor in seedlings of Hymenaea courbaril?

Abstract: The aim of this study was to establish a methodology to determine physiological vigor in small and large seeds of Hymenaea courbaril L. non-scarified seeds and scarified by the electrical conductivity test and period of seed soaking in water aiming at maximum capacity of emergence and seedling vigor. The design was completely randomized, in a 2 x 2 x 5 factorial scheme (two classes of seed mass, non-scarified seeds and scarified and five periods of soaking in water), with 10 replicates of 10 seeds each. The variables evaluated were electrical conductivity (μS cm-1.g-1), emergence speed (index), seedling emergence (%) and mean time of emergence (days), obtained by means of daily counts until stabilization in the values. Maximum vigor of Hymenaea courbaril seedlings is obtained with large seeds subjected to scarification and soaked in water for six hours. Water content of 18.7% in large seeds of Hymenaea courbaril scarified promotes the production of 100% of vigorous seedlings. Small and large seeds of Hymenaea courbaril non-scarified seeds and scarified, soaked for six hours, had shorter mean time for seedling emergence. Water content of 20.6% in small seeds of Hymenaea courbaril scarified promotes 100% seedling emergence. The electrical conductivity test applied to Hymenaea courbaril seeds can be adopted to determine seed vigor, showing speed in the obtaining of results and ease of execution.

Biometric characterization and tetrazolium test in Campomanesia phaea O. Berg. Landrum seeds

ABSTRACT: Campomanesia phaea has commercial interest because its fruits are used in the manufacture of several products, besides its high nutritional potential. Nevertheless, it has low germination potential and there is not much information in the literature. The aim of this study was to perform a biometric characterization and to establish the tetrazolium test for cambuci seeds. Seeds obtained from two collection periods were subjected to biometric evaluations (seed length, thickness, width and mass), water content, determination of the soaking curve and tetrazolium test. The soaking curve was performed with non-scarified seeds and seeds subjected to two scarification methods, mechanical and chemical. The tetrazolium test was performed soaking the seeds in a solution of 2, 3, 5 triphenyl tetrazolium chloride salt at 0.75, 1.00 and 1.50% for 4, 8 and 12 hours. After this period, the seeds were categorized as viable and non-viable. It was concluded that the cambuci seeds presented biometric differences between the two collection periods, because of the different water contents. There was no difference in the soaking curve among the three treatments tested and the solution of 0.75% for four hours in a water bath at 38 oC was considered the best for performing the tetrazolium test.

Seed dormancy of 80 tropical montane forest species in Sri Lanka, the first dormancy profile for a tropical montane forest community.

Community-level seed dormancy studies are important in understanding the dynamics of plant communities and adaptations of species to their habitat. Our aim was to develop a seed dormancy profile for tropical montane forests of Sri Lanka, which are a global biodiversity hotspot, and compare it to the profile made using a world database for this vegetation type. Germination, imbibition and embryo length : seed length ratio of seeds were determined for 80 Sri Lankan montane forest species. Seeds of 31 species were fast-germinating with a median length of germination (MLG) <30days and the remaining 49 were slow-germinating with MLG >30days. Embryos of six fast-germinating species grew prior to radicle emergence, indicating morphological dormancy (MD). The other 25 fast-germinating species had non-dormant (ND) seeds. Manually scarified seeds of two species imbibed significantly more water than non-scarified seeds, revealing physical dormancy (PY). Embryos of 20 slow-germinating species grew prior to radicle emergence, confirming morpho-physiological dormancy (MPD). The remaining slow-germinating species had a fully developed embryo and thus physiological dormancy (PD). The percentage of species with ND seeds and with MD, MDP, PD and PY was 31, 7.5, 25, 34 and 2.5, respectively. Species with dormant seeds (70%) dominate the Sri Lankan montane forest community similar to the world database, with 85% dormant seeds. Seed dormancy may be an adaptation that prevents seeds from germinating during the Sri Lankan dry season from December to March when conditions are unfavourable for seedling growth due to low water availability.

Seed dormancy of Cardiospermum halicacabum (Sapindaceae) from three precipitation zones in Sri Lanka.

This study investigated seed germination of Cardiospermum halicacabum, a medicinally important invasive species. We compared mass, moisture content (MC), dormancy and dormancy-breaking treatments and imbibition and germination of scarified and non-scarified seeds of C. halicacabum from a low-elevation dry zone (DZ), low-elevation wet zone (WZ1) and mid-elevation wet zone (WZ2) in Sri Lanka to test the hypothesis that the percentage of seeds with water-impermeable seed coats (physical dormancy, PY) decreases with increased precipitation. Seed mass was higher in WZ2 than in DZ and WZ1, while seed MC did not vary among the zones. All scarified DZ, WZ1 and WZ2 and non-scarified DZ and WZ1 seeds imbibed water, but only a few non-scarified WZ2 seeds did so. When DZ and WZ1 seeds were desiccated, MC and percentage imbibition decreased, showing that these seeds have the ability to develop PY. GA3 promoted germination of embryos excised from fresh DZ and WZ1 seeds and of scarified WZ2 seeds. At maturity, seeds from DZ and WZ1 had only physiological dormancy (PD), while those from WZ2 had combinational dormancy (PY+PD). Thus, our hypothesis was not supported. Since a high percentage of excised embryos developed into normal seedlings; this is a low-cost method to produce C. halicacabum plants for medicinal and ornamental purposes.

Dormancy breakage in Cercis chinensis seeds

The seeds of Cercis chinensis Bunge are important for reproduction and propagation, but strong dormancy controls their germination. To elucidate the causes of seed dormancy in C. chinensis, we investigated the permeability of the hard seed coat and the contribution of the endosperm to physical dormancy, and we examined the effect of extracts from the seed coat and endosperm. In addition, the effectiveness of scarification methods to break seed dormancy was compared. Cercis chinensis seeds exhibited physical and physiological dormancy. The hard seed coat played an important role in limiting water uptake, and the endosperm acted as a physical barrier that restricted embryo development in imbibed seeds. Germination percentage of Chinese cabbage [Brassica rapa subsp. chinensis (L.) Hanelt] seeds was reduced from 98% (control) to 28.3% and 56.7% with a seed-coat extract and an endosperm extract, respectively. This demonstrated that both the seed coat and endosperm contained endogenous inhibitors, but the seed-coat extract resulted in stronger inhibition. Mechanical scarification, thermal scarification, and chemical scarification had positive effects on C. chinensis seed germination. Soaking non-scarified seeds in gibberellic acid (GA3) solution did not promote germination; however, treatment with exogenous GA3 following scarification significantly improved germination. The optimal method for promoting C. chinensis seed germination was soaking scarified seeds in 500 mg·L−1 GA3 for 24 h followed by cold stratification at 5 °C for 2 mo.

Effect of different priming treatments on seed germination of sago palm (Cycas revoluta L.)

King sago palm or sago cycas are the other name of Kangi palm ( Cycas revoluta ) sago palm has been used as an indoor and outdoor landscape plant for centuries. The present study was conducted to estimate the effect of different priming treatments on seed germination of sago palm ( Cycas revoluta L.) in the research area of Department of Horticulture PMAS, University of Arid Agriculture Rawalpindi, Pakistan. The Experiment consisted of ten treatments; the seeds without pulp were soaked in solution of 500, 750 and 1000 ppm GA 3 and 2%, 3% and 4% solution of KNO 3 for 24 hr at room temperature. In case of hot water treatment, seeds were primed at 80 o C, 90 o C and 100 o C for 30, 20 and 10 minutes respectively. The effect of different concentrations of gibberellic acid (GA 3 ), potassium nitrate (KNO 3 ) and hot water on various parameters like germination rate, germination percentage, germination value, decayed seed percentage, time of germination, number of leaves and seedling height were studied. Significant results of germination rate (55.56 days), germination value (192.19) were achieved from 500 ppm GA 3 . Maximum germination percentage (73.33%) and number of leaves (2) were observed in KNO 3 at 2% followed by 500 ppm GA 3 . Similarly lowest decayed seed percentage (26.66%) and time of germination (59.41 days) were noted in 2% KNO 3 . The seedling height was optimum (19.33 cm) in 3% KNO 3 followed by 2% KNO 3 . Best germination results were obtained due to permeability of hard seed coat made by low concentrations of priming treatments (KNO 3 @ 3%).

Reproductive strategies and dimorphic seeds germination in Trifolium argentinense Speg., an amphicarpic species

Native from Rio Grande do Sul natural pastures, Trifolium argentinense Speg. has sexual reproduction through aerial and subterranean seeds (amphicarpy) and vegetative reproduction by regrowth from storage roots. In this study the seeds produced at the soil-surface flowers, the depth effect and scarification on the aerial and subterranean seeds germination and the storage roots produced by plants derived from the two types of seeds were evaluated. The aerial (0.10 cm) and soil-surface (0.11 cm) seeds were similar in size, but smaller than the subterranean seeds (0.14 cm), with no significant variation in the production of the three types of seeds. Aerial and subterranean seeds scarified at and sowed 2.5 cm deep germinated better than the scarified and non-scarified seeds sowed on the soil-surface and at 7.0 cm, evincing a depth effect on seed germination. Although amphicarpic, T. argentinense first invests in the production of the storage roots making sure the cloning of specific genotypes and allowing the plants to persist vegetatively year after year without the need for regeneration by seeds in unfavorable environments for sexual reproduction, such as in Rio Grande do Sul natural pastures, where hard grazing and trampling can destroy the aerial part of the plants.&#x0D;

Seed Treatment Techniques to Improve Germination of Wild Asparagus (Asparagus acutifolius L.), a Potential New Crop

Pre-sowing seed treatment techniques of stratification and scarification were used in order to find the most appropriate method to overcome dormancy of wild asparagus (Asparagus acutifolius L.) seeds. An indoor and an outdoor experiment were carried out at the Agricultural University of Athens. For the indoor experiment, the pre-sowing treatments of stratification (fresh and stratified seeds) and scarification (non-scarified, mechanical scarification and chemical scarification with sulfuric acid) were used as the main treatments, and three different temperatures (15, 20 and 25 °C) as sub-treatments. For the outdoor experiment, there were only the treatments of stratification and scarification. The stratification of asparagus seeds was found to have a positive effect on germination and vigor indices compared to non-stratified (fresh) seeds. The highest germination percentage, vigor index I and II were recorded with the stratified seeds that had been mechanically scarified in both indoor and outdoor conditions. The results indicate that just the scarification cannot improve germination of fresh collected seeds of wild asparagus. Stratification increased the germination percentage from 2.7-6.6% to 45.1-75.3%. The mechanical and the chemical scarification had a positive effect on the root length compared to the non-scarified seeds that have been stratified. These pre-sowing treatments can increase the germination percentage and produce vigorous seedlings that can be used to establish plantations of this potential new crop.

Implication of some pre-germination treatments on seeds and initial seedling growth of pomegranate (Punica granatum L.)

Pomegranate stands out as healthy fruit due to its phytochemical compounds. Some dormancy studies have stated the need to understand seed physiology, subsequent seedling production, as producers intended to expand the supply of pomegranate, besides facilitating the introduction of such promising crop. Thus, this study aimed to identify possible integumentary dormancy in seeds of pomegranate cultivar Comum and to evaluate the effect of mechanical scarification and water immersion of seeds, as overcoming method. In this study, sarcotesta was removed from scarified and non-scarified seeds, and then immersed in deionised water for up to 0, 12, 24 and 48 hours. Then seeds were embedded in trays of expanded polystyrene with organic substrate at greenhouse. The following evaluations were carried out: initial emergence, speed index, mean time of emergence and emergence percentage, besides biometric variables such as leaf number, stem diameter, length of aerial part and root system, fresh matter and total dry matter. A 2 x 4 factorial arrangement (presence or absence of scarification x four immersion time) in a completely randomized design was used, with 4 replicates of 25 seeds each. The results showed that seeds do not need to be scarified and immersed in water, regarding to both emergence and initial seedling growth variables. Results indicated that it was unnecessary to perform scarification and water immersion for emergence and initial growth variables, leading to conclusion that pomegranate seeds cv. Comum have no integumentary dormancy.

CARACTERIZAÇÃO DA TESTA DE SEMENTES DE &lt;i&gt;Apuleia leiocarpa&lt;/i&gt; (VOGEL) J. F. MACBR) APÓS SUPERAÇÃO DE DORMÊNCIA

A dormência é um fenômeno intrínseco da semente, funcionando como mecanismo de resistência natural aos fatores adversos do meio. A germinação só ocorrerá quando esta for superada e as condições ambientais forem favoráveis ao crescimento das plântulas. O objetivo deste trabalho foi analisar o efeito de tratamentos para superação da dormência na estrutura da testa de sementes de Apuleia leiocarpa pela microscopia eletrônica de varredura. Os métodos pré-germinativos para superação da dormência foram: sementes não escarificadas (testemunha), imersão em ácido sulfúrico 75 e 98% por três e nove minutos e imersão em água aquecida a 80ºC por 30 segundos. As sementes foram submetidas às análises em microscopia e foram avaliadas pelo teste de germinação. Os tratamentos foram eficientes em romper a exotesta das sementes de garapa, sendo que o ácido promoveu elevado incremento na germinação. A água aquecida causou a morte das sementes.