Scarified Seeds Research Articles

Absorption Curve and Germination of Jucá Seeds under Different Salts

<p>The plants are subjected to conditions of multiple stresses that limit their growth and development, which affects their chances of survival wherever they grow. To evaluate the plant tolerance to these conditions, one of the most used methods is the observation of seed germination under salt stress. The action of salts on the seeds varies widely among species and can exert toxic effects, causing damage before and/or after the onset of germination. Therefore, the objective of this work was to evaluate the influence of different salts in water absorption and germination in jucá seeds (<em>Libidibia ferrea</em>). For absorption and germination curve, were used non-scarified and scarified seeds, and subjected to the treatments in distilled water (control) and NaCl solutions, KCl, CaCl<sub>2</sub> and K<sub>2</sub>HPO<sub>4</sub>, in an electric conductivity of 5 dS m<sup>-1</sup>. The saline solution composed by K<sub>2</sub>HPO<sub>4</sub> influence on water absorption of <em>L. ferrea</em> in intact seeds. The scarified and non-scarified seeds of <em>L. ferrea</em> have different times for the physiological phases of water absorption. The action of salts in the germination and vigor in non-scarified and scarified seeds, does not significantly reduce these values due to electrical conductivity of 5 dS m<sup>-1</sup> not be enough to affect the seed germination of <em>L. ferrea</em>.</p>

Scarification and stratification protocols for raspberry (Rubus idaeusL.) seed germination

Breeders need to know the seed germination requirements for the species under study, because sexual propagation is used to increase specific progeny. In the genus Rubus, low germination percentages are frequently obtained and can effect seed propagation protocols. Seeds have a hard testa, and their embryo can require a period of cold storage to overcome dormancy. These seeds are called “double dormant” and require pre-germination treatments. The requirements for scarification and stratification of Rubus seeds can be better defined. The objective of this study was to test different pre-germination treatments on seeds derived from inter-cultivar crosses of Rubus idaeus. The seeds were subjected to specific concentrations of sulfuric acid (0, 5, 50, and 95%) for 30 min, before starting the process of cold storage. To estimate the optimum period of stratification, different treatment times of 60, 90, and 120 days were tested. The results indicated that the best treatment to scarify seeds of our R. idaeus crosses was with 95% sulfuric acid. The best treatment for stratification was three months.

Chloroleucon chacoense (Leguminosae): A Study on Morphometry of Fruits and Seeds, Germinability and Development of Seedlings

The dehiscent legumes of Chloroleucon chacoense (Leguminosae, Mimosoideae) are highly predated. The seeds of an intermediate type (neither orthodox, nor recalcitrant) remain in latency until the rainy station start can germinate efficiently when are imbibed 36 h in water before the sown, reaching similar % than those treated with sand paper or sulphuric acid. The seeds lose their germinability when are treated with warm water, perhaps because it kills the embryo. The seedlings are developed in a high percentage (92%) although they do not receive scarification treatments. The scarified seeds increase their weight more than the no scarified, as the Baskin Index denotes. The ANOVA and MTG show that the mechanical and chemical treatments allow the seeds to germinate till 24 h since the sown. The “t” test highlights that the no scarified seeds exhibit high difference of weight only at 24 h since the sown; perhaps the seeds need that lapse of time to imbibe to start the germination. Between the unhealthy seeds, those with arrested development constitute a high percentage, and perhaps some problems in the reproductive system exist. The germination is epigeal, phanerocotyledonar, with photosynthesizing cotyledons, and the seedlings have two sub-opposite protophylls (one pinnate, the other bipinnate) and two or more alternate, bipinnate eophylls. This fact implies that the classification commonly used does not cover the variability existent in the Leguminosae. Studies are needed to elucidate the origin of the low density of individuals because the species is included in the RED BOOK.

English

The aim of the present investigation was to evaluate various methods for breaking dormancy of Crotalaria senegalensis seeds. The seeds were subjected to the following treatments for physical and physiological dormancy breaks: (1) physical scarification which carried out by soaking intact seeds in distilled water for 24 h at ambient temperature (25°C) , soaking in hot distilled water (80°C) for 15 and 30 min, immersion in H2SO4 (98%) for 5, 15 and 30 min and mechanical scarification by sand paper. The physiological dormancy break treatments include: (1) soaking scarified seeds in distilled water for 24 h at ambient temperature (25°C), (2) immersion in 1%, 2% and 4% KNO3 and (3) soaking in golden leaf purslane extract for 8, 16 and 24 h. All scarification treatments improved the germination capacity of C. senegalensis seeds, the highest being after soaking in golden leaf extract followed by soaking scarified seeds in water for 24 h and immersion in 1% KNO3. The results showed that using mechanical scarification with sand paper and immersion seeds in H2SO4 (98%) for 30 min to break seed physical dormancy of C. senegalensis was the most effective treatments but inefficient because mechanical scarification break small seeds of the crotalaria especially for large quantities lots and it was proven to be a labor intensive process. On the other hand the acid H2SO4 treatment is costly and dangerous in handling. To break physiological dormancy of C. senegalensis seeds, soaking in golden leaf purslane extract for 16 h represent the most recommended treatment.

Germinación, dispersión y establecimiento de plántulas de <i>Mimosa tenuiflora</i> (Leguminosae) en México

Mimosa tenuiflora (Willd.) Poir. is an important natural resource in Mexico, due to its diverse uses. However, seed germination, dissemination and seedling establishment of this species had not been studied up to date. Fruits and seeds were collected in the State of Chiapas, Mexico (S. L. Camargo el al. 118, U AMIZ). Germinatíon experiments were carried out afier four years of seed storage; I 935 seeds were sown in Petri dishes containing moistened Wathman filter papero Optimum temperatures were determined in a gradíent 5-40 ° C, with continuous light for mechanically scarified and non scarified seeds. Three photoperiod experiments were made: a) continuous light, b) constant darkness and e) 12 hr lightJ12 hr darkness. Three germinate pretreatments were applied: al meehanical scarification, b) sulfuric acid scarification, el fire scarification and d) control. Three replicates of 15 seeds each were made for each variable and pretreatment. Standard deviations (S) were determined, a one-way analysis of variance ( ANOVAl and media comparison (Scheffé's test) were applied (p<0.05). Analysis of fruit and seed dissemination and seedling establishment was made qualitatively on the basis of field and laboratory observations; radius of dissemination of the fruits from the mother plant was measured; development of laboratory grown seedlings was followed during three months. Seeds germinated al 10- 3(J°C; however, the highest percentages of geCllÚnation were obtained at 200e (84.44%) and 25°C (95.55%); seeds are indistinctIy photoblastic and percentages of germination, afier the three germinate pretreatments, were: control (24.44- 35.55%), mechanical scarification (84.44-88.88%), sulfuric acid searificatÍon (73.33-91.11%) and fire scarification (0% l. Fruits and seeds are disseminated by the wind in a radius of 5-8 m fram the mother plant; rain carrÍes them from slopes to lower plains and human activities contri bu te to their dissemination. Growth of seedlings is fast; they develop a paripinnate protophyll and ten biparipinnate pronomophylls; the first nomophyll develops during the weeks 12 to 14. lt is concluded that optimum temperatures for seed germination of M. tenuiflora are 20 ° C and 2S o C; seeds are indistinctly photoblastic; percentage and rate of germination are highly increased by coat scarification. This species has certain advantages for its establishment in open areas, given by the abundant production of seeds, thelr small size, the rate of germination and Ihe fast growlh, as well as by its seedling characters: the tap root system, the hypocotyl-epicotyl axis woody at the base and, the eompound leaves with Iinear-oblong leaflets having changes in orientation in response to light. Our results confirm the invasive and typically secondary character of this species.

Germination of Eryngium regnellii: a major species for ecological restoration of plant-pollinator interactions in the Southern Pampas (Buenos Aires, Argentina)

<i>Eryngium regnellii</i> Malme belongs to the largest genera in the Apiaceae family, with 250 species worldwide and 65 represented in South America. It is a herbaceous species typical of hill plant communities, which, along with remnant grassland patches, are the most relevant natural habitats for the maintenance of diversity in the Southern Pampas. <i>Eryngium regnellii</i> is key to the maintenance of pollination mutualisms, being a generalist (displaying a diverse assemblage of pollinators) and ubiquitous species (present in all studied sierras). However, fragmentation of the Pampean landscape due to agricultural intensification has led to the loss of natural environments. Therefore, the reintroduction of <i>E. regnellii</i> in strategic places would facilitate the occurrence of wild pollinators, while favoring pollination services in the agroecosystem. The germination requirements of <i>E. regnellii</i> were studied because a better knowledge of the reproductive biology of this species would provide information relevant to its reproduction and reintroduction into degraded areas. Germination percentages and mean time to germination were evaluated, using one control and two pre-germination treatments: chemical scarification with sulfuric acid, and mechanical scarification with sand paper. Chemical scarified seeds did not germinate. Mechanically scarified and control seed groups showed no significant differences either in germination percentages (49% and 59% respectively) or in mean germination time (13 and 14 days, respectively). Results indicate that <i>E. regnellii</i> shows no physical dormancy, and does not require specific pre-germination treatments for germination under the studied laboratory conditions. The high germination capacity of <i>E. regnellii</i>, along with its ecological attributes, make it a potential species for restoring plant-pollinator interactions in the fragmented landscapes of the Southern Pampas.

Composting Invasive Plants in the Rio Grande River

AbstractThe purpose of this study was to determine the effect of whole-plant composting on the viability of seeds and other propagules of the invasive plant species waterhyacinth, waterlettuce, hydrilla, and giant reed while producing a valuable compost product. Invasive species were subjected to preliminary germination and growth tests and oven mortality tests to evaluate whether species distribution was via seeds, vegetative propagules, or both, as well as whether the composting process had the potential, through the high temperatures obtained, to kill seeds and other propagules. Germination and growth tests determined the means by which invasive species spread. Oven tests determined the temperatures at which unscarified and scarified seeds and propagules were rendered inviable. Achieving temperatures of at least 57.2 C was necessary within constructed compost piles to effectively kill the plants without the danger of redistribution. In the field, the study successfully developed a large-scale composting operation using invasive plant species as the primary feedstock. Analysis of field-scale composting showed final materials were within satisfactory to ideal levels for samples analyzed by the U.S. Compost Council's Seal of Testing Assurance Program and were, therefore, a valuable compost product.

Desempenho fisiológico e superação de dormência em sementes de Brachiaria brizantha submetidas a tratamento químico e envelhecimento artificial

The use of seeds of B. brizantha has increased, however, the physiological quality of seeds available to the producer is still a limiting factor for a good performance culture. The objective of this study was to evaluate the effects caused by chemical scarification, different periods of aging and priming on physiological quality and overcoming seed dormancy B. brizantha cv. MG-5 Victory. The seeds were subjected to chemical scarification – H2SO4 (presence and absence), artificial aging periods (zero, 24, 48, 72, 96, 120, 144 and 168 hours) at 41 ° C and priming using the 0,2 KNO3 % (presence and absence) for two hours at 25 o C, creating a completely randomized design in factorial 2x8x2, with four repetitions. The seeds were evaluated by testing germination and vigor. Chemical scarification is an effective method for breaking dormancy, but decreases the physiological seed. Overcoming seed dormancy B. brizantha occurs with the use of artificial aging for non-scarified and scarified seeds. Priming generally has no effect on the physiological quality and overcoming seed dormancy B. brizantha , however, it provides less loss of cellular constituents.

Seed biology and possibility of improvement of seed germination capacity on Virginia mallow (Sida hermaphrodita L. Rusby)

Sida hermephrodita or Virginia mallow is a perspective perennial herb in the Malvaceae family able to yield a biomass crop through the last two decades. Additionally, the plants have a lot of uses and benefits for instance it can use as a fodder crop, honey crop, ornamental plant in public gardens. It has favourable features like fast growing and resistance against the disease and climatic fluctuations, etc. Sida is in the beginning phase of domestication therefore it has a serious disadvantage: the low and slow germination as a big part of wild plants. Due to the expressly low germination percent the need of seed showing of driller is should tenfold, 200 thousand seeds/acre instead of 10–20 thousand what is not available and expensive Therefore practical purposes of our research of seed physiology was to increase the seed germination percent in a available, basically wild Sida population. In the first stage of our experiments we examined two factors relating to seed germination percent and seed germination power during our research: the influence of hot water treatment and the effect of exogenous or endogenous infection of seed. However, in our germination tests, utilizing scarified seeds with hot water (65 oC, 80 oC, 90 oC), from 29,3% to 46% germinated from those samples which were collected from the population of Sida hermaphrodita in Debrecen. The average germination for all season was 5–10% without treatment and rinsed using hot water up to almost 50%. When physically scarified used, the oldest seeds showed the best germination (46%) after the hot water operation in spite of the previous studies. We discovered that apparently there are close relationship between the seed fresh weight or water uptake capability and the percentage of infection. Following these recognition we modified our technique,in such a way that we fractionated the seeds based on their fresh weight/or relative density before we carried out the treatment. When we filtered the floating seeds on the surface of water, the hot water treatment was performed considerably better on the sunk seeds after separation. Therefore, by this special priming process we were able to reach 80% germination capacity of Virgina mallow seeds under laboratory conditions (26 oC without illumination).

Dormancy-breaking and germination requirements for seeds of Acacia papyrocarpa, Acacia oswaldii and Senna artemisioides ssp.×coriacea, three Australian arid-zone Fabaceae species

Physical dormancy is common in seeds of arid-land legumes. Improved understanding of germination requirements of hard-seeded species will further our understanding of arid lands and aid restoration projects. We studied the germination responses of Acacia papyrocarpa (Benth.), A. oswaldii (F.Muell) and Senna artemisioides (Gaudich. ex DC.) Randell ssp. × coriacea (Benth.) Randell from a chenopod shrubland in South Australia. Imbibition testing indicated that all three species had physical dormancy, but the proportion of dormant seeds was lower in A. oswaldii. This corresponded to a thinner testa in this species. Mechanisms tested to scarify seeds included mechanical scarification and different durations of wet or dry heat. Mechanically scarified seeds germinated readily, reaching maximum numbers in 10–15 days, independently of incubation temperatures, with the exception of S. artemisioides seeds, which germinated at a slower rate in cooler temperatures. Overall, wet heat was more effective than dry heat to alleviate physical dormancy, whereas dry heat in some cases resulted in seed mortality. On the basis of these results, it is recommended that seeds of A. papyrocarpa and S. artemisoides be pretreated with wet heat in future restoration programs. No pre-treatment is required for dormancy loss in A. oswaldii seeds. The different responses of seeds of these species suggest that their populations have varying strategies for persistence in this unpredictable environment.

English

The study conducted to standardize the seed dormancy breaking treatment in senna (Cassia auriculata) revealed that soaking the seeds in hot water (boiled to 100&deg;C and removed from the flame) for 15 min and soaking with 100 ppm GA3 for 3 h had effectively improved the germination (98%), root length (7.2 cm), shoot length (9.5 cm), dry matter production (0.258 g per ten seedlings) and vigour index (1637) compared to hot water treatment for 15 min alone (89% germination) and non-scarified seeds (20% germination). The seeds scarified with concentrated sulphuric acid also showed better germination than the non scarified seeds but less than the hot water scarified seeds. Key words: Senna, Cassia auriculata, seed dormancy breaking, hot water treatment.

Lecythis pisonis Cambess (sapucaia): seed morphometric traits and germinative response

This study aimed to test a possible correlation between germination and the variables weight and density of seeds of Lecythis pisonis (sapucaia), as well as raise issues which may contribute to know germination in this species. For this, we followed up the soaking and germination process of intact and scarified seeds of L. pisonis under controlled conditions (26°C, with average irradiance of 34.6 mmol.m-2.s-1 and in the dark). In another trial, seeds of sapucaia were individually characterized with regard to weight and density, and, then, sown in plastic boxes filled with soil and kept in a natural environment (average irradiance ±12.5 mmol.m-2.s-1 at 12:00 p.m.), with temperatures ranging from 15 to 32°C. The germination (shoot emergence) of each seed was followed up within the period from September 2009 to January 2010. The results suggest that the coat does not represent a restrictive factor for soaking and germination of sapucaia. Germination increased proportionally to the increase in seed density. Based on these results, we recommend the use of seeds with densities > 0.9 g.mL-1, in order to ensure a high percentage of seedlings.

Relation between the germination and infection ratio on Sida hermaphrodita L. Rusby seeds under hot water treatment

Sida hermephrodita or virginia mallow is a perspective perennial herb in the Malvaceae family able to yield a biomass crop through between ten and twenty years. Additionally, the plants have a lot of uses and benefits for instance it can use it as a fodder crop, honey crop, ornamental plant in public gardens. It has favorable features like fast growing and resistance against the disease and climatic fluctuations, etc. Sida is in base stage of domestication therefore has a serious disadvantage the low and slow germination as a big part of wild plants. Due to the expressly low germination percent the need of seed showing of driller is should tenfold, 200 thousand seed/acre instead of 10-20 thousand what is not available and expensive Therefore practical purposes of our research of seed physiology was to increase the seed germination percent in a disposable ,basically wild Sida population. We examined two factors relating to seed germination percent and seed germination power during our research: the influence of hot water treatment and the effect of exogenus or endogenus infection of seed. However, in our germination tests, utilizing scarified seeds with hot water (65, 80 and 95 oC), 29,33 to 46% germinated of the seeds collected from the population of S. hermaphrodita in Debrecen. The average germination for all season was 5-10 % wihitout treatment and rised using hot water up to almost 50%. When physically scarified used, the oldest seeds showed the best germination (46 %) after the hot water operation in spite of the previus studys (Spooner 1985; Chudik et al. 2010; Doliński R. 2009.). We discovered that there are a distinguished close relationship between the seeds collecting time and the infection, as well as germination percentage. Thus, 2009 season was the most favourable in case of contamination (control:17,33 and 80 oC treatment:0%) as well as germination percent. It could be concluded that, the best season for our findings was 2009 due to autumn harvest of Sida seeds. In our oppinion, the autumn harvesting should be the best time to overcome the problem of the low germination and high infection percentage.

Breaking physical dormancy of Cassia leptophylla and Senna macranthera (Fabaceae: Caesalpinioideae) seeds: water absorption and alternating temperatures

AbstractThis study analysed the anatomical structure of the seed coats, identified the location of water uptake and evaluated the effects of alternating temperatures and heat treatment on the breaking of physical dormancy of two species of Fabaceae (Caesalpinioideae), Cassia leptophylla and Senna macranthera, from the Atlantic forest of Brazil. The seed coats of both species consisted of a cuticle (extra-hilar region) or remaining funicle region (hilar region), subcuticular layer, palisade layer with lignin, osteosclereids, sclerified parenchyma and white cells. The palisade layer was formed by elongated macrosclereids with a light line of callose. In thermally scarified seeds of C. leptophylla, water entered through the micropylar canal, and in S. macranthera the water entered through the lens. Alternating temperatures that ranged from 15 to 30°C did not break physical dormancy of either species; however, exposure to 50°C broke seed hardcoatedness, allowing the entrance of water in both species.

Effects of seed beetles on the performance of desert legumes depend on host species, plant stage, and beetle density

Seeds of many arid habitat plants have a water-impermeable coat and can germinate only after being scarified. Bruchine seed beetles are important parasites of legume seeds in these environments, but their effect on germination can be unpredictable. Beetles deplete seed resources and can kill the embryo but also scarify seeds. We investigated the effects of a generalist parasite, Stator limbatus, on the germination and growth of two common legumes in the Sonoran desert, catclaw acacia (Acacia greggii) and blue paloverde (Parkinsonia florida). Feeding damage from a single larva greatly increased germination of paloverde but not acacia. This benefit was reduced if seeds were attacked by multiple larvae. Beetle-damaged seeds of both hosts germinated more quickly than did control seeds. Infestation by beetles reduced seedling size, though effects were greater for paloverde than for acacia. Our results demonstrate that the effect of S. limbatus can be highly host-specific. In addition, beetle infestation may enhance or reduce seedling recruitment, depending on the availability of other scarifying agents and the number of larvae per seed. Such contingencies make it difficult to predict the net effect of seed beetles on efforts to control invasive legume hosts or establish native hosts during aridland restoration.

Recovery and Germination of Dichrostachys cinerea Seeds Fed to Goats (Capra hircus)

Abstract Goats can act as dispersal agents by consuming seed pods of woody plants and dispersing the seeds in feces. Concerns that goats might thereby promote encroachment by woody plant species such as Dichrostachys cinerea (sickle bush) have not been addressed. The objective of this study was to determine the recovery rate and germination of D. cinerea seeds that pass through the digestive tract of goats. We hypothesized that 1) D. cinerea seeds will remain intact and viable after passage through the digestive tract of goats and that 2) D. cinerea seeds will be scarified by such passage, resulting in improved germination percentages. The first trial measured the recovery rate of 1 500 D. cinerea seeds that were consumed by indigenous goats, either voluntarily after mixing them with feed pellets (mixed) or by force-feeding (gavaged). Seed recovery for the gavaged treatment (32.7%) was significantly higher than for the mixed treatment (9.9%; P s 0.001). The second trial determined germination percentages of D. cinerea seeds recovered from the feces of animals in the two treatments of the first trial as well as scarified and control (untreated) seeds. The germination percentage of mechanically scarified seeds (53.0%) was significantly higher than that of seeds that passed through the digestive system in the mixed (35.5%) or gavaged (31.2%) treatments or were untreated (19.0%; P s 0.001). Seeds that passed through the digestive tract (mixed and gavaged treatments) had a significantly higher germination percentage than untreated seeds ( P s 0.001). A nonnegligible proportion of D. cinerea seeds remained intact after ingestive chewing and passage through the digestive system, and their germination percentage was even elevated. This suggests that goats have a potential to facilitate woody plant encroachment through dispersal of viable and scarified seeds.

English

Low and erratic germination in wild banana seed is caused by dormancy due to physical, anatomical or physiological reasons. Imbibition activates germination process and the rate of water uptake during imbibition is influenced by seed molecular composition and internal and external morphological structures. The present study aimed at examining the effect of seed anatomy and seed moisture content on water uptake by wild banana seeds. Matured fresh and dry, intact or scarified seeds of three wild banana ecotypes (Musa acuminata&nbsp;Colla) viz. Krau White, Serdang Red and Serdang Yellow were imbibed for up to 96 h. Percentage increase in seed mass was recorded at different intervals. Internal morphological structures of fresh and dry seeds were viewed using scanning electron microscopy (SEM). Seed mass increased rapidly within first hour and the rate of increase was always higher in dry seed than the fresh seed in all the ecotypes. The SEM observation revealed that the rapid increase of seed mass is likely due to the shrinking of the operculum and the surrounding tissues in the hilum area which resulted in the formation and widening of a water channel in dry seed. This study indicates that operculum does not impede water uptake in mature banana seed during imbibition, suggesting that seed dormancy in these three ecotypes is not due to physical dormancy but may be physiological in nature. &nbsp; Key words:&nbsp;Musa&nbsp;acuminata,&nbsp;imbibition, seed coat, scarification, physical dormancy.

PELICULIZAÇÃO DE SEMENTES INTACTAS E ESCARIFICADAS DE Brachiaria brizantha (Hochst. ex A. Rich.) Stapf

Brazil is the largest producer, consumer, and exporter of forage seeds, requiring new technologies and treatments to maintain and expand this market. The aim of this study was to evaluate the film coating (polymer, fungicide, and dye) effect, preceded or not by acid scarification, on commercial Brachiaria brizantha seeds germination, under water stress conditions, simulated in laboratory. Seeds, intact or scarified with sulfuric acid, with or without film coating, all from the same batch, were evaluated by using a germination test, immediately (0 MPa, -0.3 MPa, -0.6 MPa, -0.9 MPa, and -1.2 MPa) and six months (0 MPa, -0.1 MPa, -0.2 MPa, and -0.4 MPa) after the treatment, in hydric potentials induced by mannitol, simulating water deficiency. Seeds were stored at 20oC and 60% RH, in an acclimatized room, and counting was carried out at 7, 14, and 21 days, with data delineated in germination percentage and seeds infected by fungus. The imbibition curve was obtained at the first period, over paper, without hydric restriction, at 25oC, for 96 hours. It was concluded that film coating and scarification treatments can restrict seeds imbibition after 96 hours; scarification with sulfuric acid promotes seeds germination; film coating is effective to control fungi, especially under water deficit; and that film coating can be used to limit scarified seeds germination under water deficit.

Interchangeable effects of gibberellic acid and temperature on embryo growth, seed germination and epicotyl emergence in Ribes multiflorum ssp. sandalioticum (Grossulariaceae)

Morphophysiological dormancy was investigated in seeds of Ribes multiflorum Kit ex Roem et Schult. ssp. sandalioticum Arrigoni, a rare mountain species endemic to Sardinia (Italy). There were no differences in imbibition rates between intact and scarified seeds, suggesting a lack of physical dormancy, while methylene blue solution (0.5%) highlighted a preferential pathway for solution entrance through the raphe. Embryos were small at seed dispersal, with an initial embryo:seed ratio (E:S) of ca. 0.2 (embryo length, ca. 0.5 mm), whereas the critical E:S ratio for germination was three times longer (ca. 0.6). Gibberellic acid (GA(3), 250 mg · l(-1)) and warm stratification (25 °C for 3 months) followed by low temperature (<15 °C) enhanced embryo growth rate (maximum of ca. 0.04 mm · day(-1) at 10 °C) and subsequent seed germination (radicle emergence; ca. 80% at 10 °C). Low germination occurred at warmer temperatures, and cold stratification (5 °C for 3 months) induced secondary dormancy. After radicle emergence, epicotyl emergence was delayed for ca. 2 months for seeds from three different populations. Mean time of epicotyl emergence was affected by GA(3) . Seeds of this species showed non-deep simple (root) - non-deep simple (epicotyl) morphophysiological dormancy, highlighting a high synchronisation with Mediterranean seasonality in all the investigated populations.

Escarificação química para a superação da dormência de sementes de saguaraji-vermelho (Colubrina glandulosa Perk. - Rhamnaceae)

Este trabalho objetivou avaliar diferentes períodos de imersão de sementes de saguaraji-vermelho (Colubrina glandulosa) em ácido sulfúrico, para a superação da dormência. O experimento foi dividido em duas etapas. Na primeira, sementes de cinco lotes provenientes de diferentes localidades (dois recém-coletados e os demais armazenados por um, dois e três anos) foram escarificadas quimicamente com ácido sulfúrico concentrado por 30, 60, 90, 120 e 150 min. Na segunda etapa, as sementes dos lotes recém-coletados foram imersas em ácido por 20, 30, 40, 50 e 60 min. As sementes escarificadas com ácido e as não escarificadas foram avaliadas diariamente quanto à germinação (rolo de papel, 25 ºC, no escuro e quatro repetições de 25 sementes por tratamento) - com os dados, foram calculadas sua porcentagem e velocidade. Na primeira fase, as médias dos tratamentos foram comparadas pelo teste de Tukey (P&lt;0,05) e na segunda, por equações de regressão. Os resultados indicaram que a porcentagem de dormência variou entre as sementes dos lotes (taxas mais altas das sementes recém-colhidas), e a escarificação com ácido por 30 a 90 min foi favorável à superação da dormência. Houve prejuízo na germinação com a escarificação das sementes por 120 min e 150 min. Na segunda fase, valores máximos de porcentagem e velocidade de germinação foram obtidos após 60 min de imersão. Diante desses resultados, o armazenamento por um ano e a imersão das sementes em ácido sulfúrico por 30 a 90 min podem ser utilizados, com eficiência, para a superação da dormência de sementes de saguaraji-vermelho.