Mechanical Scarification Treatments Research Articles

Effect of Pre-Germinative Treatments on Eight Priority Native Species for Reforestation in the Tropical Deciduous Forest

Increasing the germination percentages from chemical and/or mechanical processes in native species is vital for the conservation of the species. The objective was to evaluate the effect of different treatments on the germination process of species belonging to the tropical deciduous forest (TDF) in a forest nursery. Eight species of trees and shrubs reported to be native to the TDF were selected; the seeds were collected from various sites of the state of Queretaro, Mexico. A randomized design of four replicates with 25 seeds was used, for which three pre-germinative scarification treatments were evaluated for each species: (1) thermal scarification (TS), (2) mechanical scarification (MS), and (3) chemical scarification (CS). Germination was considered as the protrusion of cotyledons onto the substrate and was recorded every 48 h for 60 days. A significant difference was observed between treatments (p ≤ 0.05). The mechanical treatment (MS) obtained the highest germination percentage and the least variation, in contrast to the thermal, chemical, and control treatments, which presented the lowest amount of germinated seeds. The MS treatment was the most effective for all the species studied because it allowed for 100% of the germination to be achieved.

INITIAL SEED WEIGHT AND SCARIFICATION AFFECT in vitro GERMINATION OF Echinocactus parryi (Engelm.)

The endemic and threatened species Echinocactus parryi, native to the municipality of Juarez, Chihuahua, Mexico, presents important limitations for its reproduction and natural propagation. It is hypothesized that initial seed weight and scarification would affect the percentage of seed germination of this species. The objective was to compare the effect of initial seed weight (two levels) and scarification treatments (four levels) on in vitro germination of E. parryi. The morphology of seedlings grown for 12 months was also described. Four hundred seeds were divided into two groups of 200 seeds each: first group, seeds of 35 to 45 mg; and second group, seeds of 46 to 55 mg. The scarification treatments were a control (intact seeds), mechanical scarification, application of 25 % sulfuric acid and Murashige and Skoog growing medium added with 2 mg L-1 of gibberellic acid. Fifty seeds per treatment were placed for each weight group. Treatments were distributed in a completely randomized experiment with factorial arrangement. Data were subjected to analysis of variance and means were compared by Tukey’s test (p ≥ 0.05). Results showed significance in the interaction of seed weight and mechanical scarification treatment by obtaining 93.2±3.6 % germination in seeds of 35 to 45 mg and 96.0±3.3 % in seeds of 46 to 55 mg at 30 d of in vitro culture. The morphological description of the seedlings provided information on the development of E. parryi in juvenile stages, which differs from the adult stage. Results on germination and the morphological description of the seedlings represent an important advance for propagation and conservation purposes. To our knowledge, this is the first report on scarification treatment in seeds of different weights and the influence on germination, that also recorded the seedling morphology of E. parryi.

Germination of Larrea divaricata Cav, an important shrub species to restore desertified arid ecosystems

Knowledge of pre-germination seed treatments is critical for ecological restoration practices such as outplantings or direct seeding. However, in drylands, there is a lack of this kind of information about some species with high potential value for ecological restoration. This is the case of Larrea divaricata Cav., a native species that is dominant and can grow in degraded environments to the Monte region and arid ecosystems in Argentina. We evaluated the effects of the following treatments to break seed dormancy in this species: 1) alternation of soaking and drying periods; (2) periods of soaking and rinsing with running water; (3) mechanical scarification, and (4) control. Seed scarification was done using a novel mechanical method using two pieces of sandpaper: one fixed and the other spun using a 710 W hand drill. The variables evaluated were: (a) germination percentage (over time since imbibition and the final percentage), (b) mean time to germination, and (c) number of days before the start of germination. The mechanical scarification treatment improved all germination variables compared to the other treatments. In the mechanical scarification treatment, germination percentage was 60.7%; mean time to germination was 6.32 days, and the number of days before the start of germination was 2 days. Our results indicate that mechanical scarification is an appropriate technique for propagation of L. divaricata Cav. for large scale restoration, since many seeds can be treated quickly and this technique is easily replicable.

Evaluation of thermal, chemical, and mechanical seed scarification methods for 4 Great Basin lupine species

Seeds of most Great Basin lupine ( Lupinus spp. [Fabaceae]) species are physically dormant and thus, difficult to establish in uniform stands in seed production fields. We designed this study to examine 5 seed scarification techniques, each with 11 levels of application (including a non-scarified control), to reduce the physical seed dormancy of longspur lupine ( L. arbustus Douglas ex Lindl.), silvery lupine ( L. argenteus Pursh), hairy bigleaf lupine ( L. prunophilus M.E. Jones), and silky lupine ( L. sericeus Pursh). These 4 perennial Great Basin lupine species are of interest for both rehabilitation and restoration of degraded rangelands. We evaluated 10 treatments of each of 5 scarification methods, one mechanical, 2 thermal, and 2 chemical (sulfuric acid and sodium hypochlorite) techniques on the above-mentioned species. The sulfuric acid and the mechanical scarification treatments significantly improved germination for both silvery and silky lupine. Additionally, one thermal scarification method (60 s at 95 °C [203 °F]) was effective for silvery lupine. Both sulfuric acid and sodium hypochlorite scarification methods had treatment levels that significantly improved germination of hairy bigleaf lupine. For longspur lupine, all treatments within the 5 scarification methods either decreased or were not a significant improvement of germination as compared with the control, except for the treatment of soaking the seeds for 35 s at 95 °C (203 °F). We found scarification to be an effective tool for reducing physical dormancy in silvery lupine, hairy bigleaf lupine, and silky lupine, thus allowing for a more efficient use of limited seeds.

Cutting and Seed Propagation of Chickasaw Plum (Prunus angustifolia)

Chickasaw plum (Prunus angustifolia Marsh.) has the potential to be planted for windbreaks, wildlife, and for human consumption; however, reliable propagation protocols need to be established. Propagation of plants by seed using mechanical scarification treatment and stratification as well as stem cuttings using selected rooting hormone rates for Chickasaw plum were investigated. Seeds and stem cuttings of previous year’s growth were collected in Payne County, Oklahoma. Seed stratification treatments included 0, 30, or 60 d at 3°C. Mechanical scarification employed tip removal from seeds with a nail clipper. Stem cuttings were treated with five IBA rates (0, 100, 1000, 3000, and 7000 mg·L−1) in factorial combination with three collection times (May, August, and October). Scarifying the seed coat did not affect germination percentage. Non-scarified seeds stratified 60 d at 3°C had the highest germination at 31%. The time of year for cutting selection and amount of IBA rooting hormone applied was critical for rooting success. Rooting success was greatest at the highest IBA concentration when cuttings were harvested in May or August (44% and 49%), respectively.

Effect of Treatment on Seedling Vigour of Cassia Glauca Lam.

Cassia glauca a nitrogen fixing tree species produces hardcoated and light brown colour seeds. Seed has physical dormancy due to hardiness of testa. Suitable pretreatment to break the dormancy was investigated. Germination was enhanced from 10.22 percent (untreated) to 95.66 percent (mechanical scarification). Although mechanical scarification treatment gives early, uniform and highest germination but it is not practicable in large-scale purposes. Therefore, sulphuric acid for 30 minutes soaking is recommended.

Effect of Pre-Sowing Treatment of Enterolobium Contortisiliquum (Vell.) Morong Seed

Enterolobium contortisiliquum a nitrogen fixing tree species produces hardcoated and light brown colour seeds. Seed has physical dormancy due to hardiness of testa. Suitable pretreatment to break the dormancy was investigated. Germination was enhanced from 5.87% (untreated) to 93.17% (mechanical scarification). Although mechanical scarification treatment gives early, uniform and highest germination but it is not practicable in large-scale purposes. Therefore, sulphuric acid for 30 minutes soaking is recommended.

Effect of stratification and scarification treatments on the germination of oriental hornbeam (Carpinus orientalis) seeds

Summary Carpinus orientalis is a common species in the semi-mountainous regions of Greece and elsewhere, with significant value for goat nutrition and as a natural flame retardant. Little is known about the germination behaviour of the species. This study describes the effects of various germination treatments on the germination of fresh C. orientalis seeds which were found to have a non-deep physiological dormancy imposed both by the endosperm and the embryo. Different levels of cold and warm stratification were applied, alone and in combination with chemical and mechanical scarification treatments. In addition, an excised embryo test was conducted. Cold stratification for three months at 5°C was found to be adequate to release dormancy and allow germination of almost all viable seeds. Acid scarification reduced germination without damaging the embryo, while mechanical scarification was lethal. Experimental and discussion

Seed biology and pre-sowing treatment of Peltophorum pterocarpum (DC.) Backer ex K. Heyne

Peltophorum pterocarpum a multipurpose tree species produces hardcoated and light brown colour seeds. Seed has physical dormancy due to hardiness of testa. Suitable pretreatment to break the dormancy was investigated. Germination was enhanced from 19.50 % (untreated) to 92.30 % (mechanical scarification). Although mechanical scarification treatment gives early, uniform and highest germination but it is not practicable in large-scale purposes. Therefore, hot water soaking for 24 hours or sulphuric acid for 30 minutes soaking is recommended.

Métodos de superação da dormência e temperatura na germinação de sementes de dioclea violácea

The aim of this experiment was to overcome the dormancy and the effect of different temperatures in Dioclea violacea seeds’ germination. Two experiments were developed. In the first, it was studied the use of chemical and mechanical scarification in the overcome dormancy seeds. Therefore, were accomplished seven treatments with four replications of 15 seeds each. The experiment constituted of one testify treatment, five chemical scarification treatments (1, 2, 3, 4 and 5 hours of immersion in concentrated sulfuric acid – H 2 SO 4 ) and one mechanical scarification treatment. In the second experiment, was studied the temperature effects on germination seeds; it was constituted on six treatments with four replications with 12 seeds each. The treatments constituted of constant temperatures 15°C, 20°C, 25°C, 30°C and 35°C and the alternate temperature 20-30°C (16 and 8 hours, respectively). Germination, died seeds, hard seeds percentages, medium time germination and germination speed index were determined. The data were submitted to the variance analysis, and the averages compared by the Tukey test to 5% of probability and regression analysis. It was observed that the dormancy overcome of Dioclea violacea seeds can be done with chemical scarification, 3 to 5 hours in H 2 SO 4 , as much as with mechanical scarification. Also, it was possible to conclude that Dioclea violacea seeds germinate in a wide temperature strip, with constant temperatures of 20°C, 25°C and 35°C benefit the germination process.

Superação de dormência em sementes de três espécies de Parkia spp.

O conhecimento dos processos germinativos de sementes com tegumentos resistentes, como ocorre em algumas espécies pertencentes à família Fabaceae, pode fornecer subsídios para a produção de mudas e recomposição de áreas degradadas. As sementes de Parkia apresentam germinação natural lenta e irregular, o que pode ser atribuído à impermeabilidade do tegumento. O trabalho foi desenvolvido com o objetivo de avaliar diferentes métodos de superação de dormência física das sementes de Parkia multijuga, P. velutina e P. panurensis. Foram utilizadas sementes coletadas na Base de Operações Geólogo Pedro de Moura (BOGPM), em Coari/AM, submetidas aos seguintes tratamentos: testemunha (T0), desponte (T1), desponte seguido da imersão em água por 8 horas (T2), escarificação mecânica do tegumento em esmeril elétrico (T3), escarificação mecânica do tegumento em esmeril elétrico seguido pela imersão em água por 8 horas (T4), punção com agulha quente (T5), punção com agulha quente seguido pela imersão em água por 8 horas (T6), imersão em ácido sulfúrico (H2SO4) por 30 minutos (T7), imersão em ácido sulfúrico (H2SO4) por 20 minutos (T8), imersão em ácido sulfúrico (H2SO4) por 15 minutos (T9). As sementes de cada tratamento foram submetidas ao teste de germinação, avaliando-se a porcentagem de germinação, tempo médio de emergência de plântulas, índice de velocidade de emergência de plântulas e índice de sincronização. Em geral, todos os tratamentos pré-germinativos aplicados às sementes das três espécies, foram eficientes para aumentar a porcentagem de germinação em relação à testemunha. Os tratamentos de escarificação mecânica com esmeril elétrico na lateral da semente foram mais eficientes na superação da dormência de sementes de P. panurensis e P. multijuga, enquanto a escarificação química com ácido sulfúrico em maior tempo de imersão foi mais eficiente para as sementes de P. panurensis e P. velutina tanto para emergência de plântulas quanto para a formação de plântulas normais.

Superação da dormência em sementes de visgueiro-do-igapó (Parkia discolor)

O presente trabalho teve como objetivo avaliar os efeitos da aplicação de tratamentos pré-germinativos de escarificação mecânica, bem como pré-tratamentos com calor, sobre a germinação de sementes de visgueiro-do-igapó (Parkia discolor Spruce ex Benth.). No primeiro experimento, sob delineamento inteiramente ao acaso, com quatro repetições, foram avaliados os pré-tratamentos: testemunha (sem pré-tratamento); desponte no lado distal; desponte no lado proximal; desponte nos lados distal e proximal; lixamento no lado distal; lixamento no lado proximal; lixamento nos lados distal e proximal; perfuração do tegumento com ferro-de-solda; e perfuração com pirógrafo. No segundo experimento, foi adotado o delineamento inteiramente casualizado, em esquema fatorial 2 (calor: seco e úmido) x 4 (temperatura: 40ºC, 50ºC, 60ºC e 70ºC) x 5 (período de condicionamento: 6, 16, 24, 30 e 48 horas), com três repetições. O desponte ou lixamento das sementes na porção proximal e porções proximal e distal possibilitaram uma embebição mais rápida (143-163%, aos três dias e meio) e, conseqüentemente, melhores resultados de germinação (98-100%, aos quatro dias), do índice de velocidade de germinação (1,351-1,460) e do tempo médio de germinação (3 dias). Os pré-tratamentos com calor (úmido e seco), sob diferentes temperaturas, e por vários períodos de condicionamento não superaram a dormência de sementes de P. discolor.

Superação de Dormência em Sementes da Liana Abrus precatorius L.

Liana Abrus precatorius L. (Fabaceae) seeds were submitted to the following different treatments in order to break the tegument dormancy: T1) control; T2) mechanical scarification; T3) immersion in water at 80 oC for 5 minutes; T4) immersion in sulfuric acid for 15 minutes and T5) immersion in sulfuric acid for 30 minutes. The mechanical scarification treatment and the immersion in sulfuric acid for 30 minutes were the most efficient treatments to break the dormancy of Abrus precatorius seeds.

Laboratory Methods for Breaking Dormancy in Garlic Mustard (Alliaria petiolata) Seeds

AbstractGarlic mustard seeds are dormant at maturity, and 90 to 105 d of cold-moist stratification at 4 C have been used to induce germination. We studied methods for breaking dormancy and inducing germination without cold stratification, for use in laboratory and greenhouse experiments with garlic mustard. Seeds were collected from large infestations, stored at room temperature, and subjected to chemical and mechanical scarification treatments. For chemical scarification, seeds were immersed in 3% (v/v) H2O2 for 12, 24, or 48 h with constant stirring, or immersed in concentrated (95 to 97%) H2SO4 for 1 or 5 min with stirring. For mechanical scarification, seeds were placed in a sandpaper-lined tumbler for 1 or 3 s. Scarified seeds, along with non-scarified seeds, were placed in petri dishes on germination blotters saturated with gibberellic acid (GA3, 10−3 M) or deionized water, and incubated for 35 d at either 20/10 C or 15/6 C (12 hr/12 hr). None of the non-scarified seeds germinated, regardless of germination solution or temperature. Seeds germinated only following scarification, and only when imbibed in GA3 solutions. Seeds immersed in H2SO4 for 5 min or mechanically scarified for 3 s had the highest level of germination in GA3. Cumulative percent germination after 35 d was greater for seeds stored 30 mo (44 to 83%), than for seeds stored 6 (2 to 60%) or 18 mo (35 to 79%), regardless of scarification treatment. The germination results, along with scanning electron micrographs of seed coats, suggest that the intact garlic mustard seed coat is permeable to water but not GA3; therefore, both scarification and GA3 are needed to break dormancy and induce germination without cold stratification.

Pod and seed characteristics and effect of pretreatment on seed germination of Acacia robusta Burchell.

Acacia robusta, a multipurpose tree species produces hardcoated and dark brown colour seeds. Seed has physical dormancy due to hardiness of testa. Suitable pretreatment to break the dormancy was investigated. Germination was enhanced from 36.80% (untreated) to 92.00% (mechanical scarification). Although mechanical scarification treatment gives early, uniform and highest germination but it is not practicable in large-scale purposes. Therefore, hot water soaking for 24 hours or sulphuric acid for 15 minutes soaking is recommended.

Breaking seed dormancy in Opuntia rastrera from the Chihuahuan desert

In this paper, we investigated if germination of after-ripened seeds of Opuntia rastrera Weber could be enhanced using chemical (acid) and mechanical scarification pretreatments. O. rastrera seeds need an after-ripening period to germinate (≈50%) after 1 year and no germination occurs in younger seeds. Germination of 3-year old seeds of O. rastrera was evaluated using sulphuric acid (H 2SO 4) for different lengths of time, and mechanical scarification treatments (dry heating at 80 °C for 12 h and washing, immersion in water for 12 h and washing, and seed coat cutting with pliers). Similar to other wild Opuntia species , germination of O. rastrera seeds was not enhanced by any scarification pretreatment, demonstrating that an after-ripening period is the best—if not the unique—way to overcome physiological dormancy for this species.

Seed dormancy and longevity in Stipa tenacissima L. (Poaceae)

In the present paper we studied the life history traits related to seed germination of Stipa tenacissima, a key species in semiarid environments of western Mediterranean areas. S. tenacissima is a perennial tussock grass, which has traditionally been considered to expand mainly by vegetative propagation with little or no sexual reproduction. We analysed seed longevity as well as the type of seed dormancy and the role of the seed covers from seeds collected from different populations in SE Spain. We also studied the variation in seed germinability among populations, individuals, and years and the ability of seeds of S. tenacissima to form soil seed banks. There was significant variation in seed germination among individuals, populations and years. Lemma and palea were the main factor controlling these differences since their removal promoted higher and faster germination and eliminated the differences in germination parameters among populations. However, the control of dormancy by lemma and palea was independent of their weight, suggesting that their chemical nature plays a more important role than does size in controlling seed germination. Mechanical scarification treatments (via abrasion with sand) did not affect seed germination. The decay in seed germinability two years after seed collection and the low density of viable seeds in soils one year after seed dispersal indicated that S. tenacissima forms transient soil seed banks.

Factors affecting the germination of doum palm ( Hyphaene thebaica Mart.) seeds from the semi-arid zone of Niger, West Africa

Hard-seeded tropical tree species such as doum palm ( Hyphaene thebaica Mart.), a common component of the traditional agroforestry systems practiced in semi-arid West Africa, often present considerable problems to nursery managers because their hard, impermeable seed coats (pericarps) restrict the entry of both water and oxygen and offer high physical resistance to the growth of the embryo. Such seeds often require pretreatments in order to obtain rapid and uniform germination. To develop recommendations for obtaining high rates of seed germination for doum palm, three 100-day long experiments were conducted following application of different pretreatments. For freshly-collected seeds, the effects of 3 ecozones (northern, central and southern), 3 mechanical scarification treatments, and 10 different types and durations of water-soaking treatments were determined. In the second experiment, 13-month-old seeds from the southern ecozone were used to assess the effects of the same mechanical scarification and water-soaking treatments used in the first experiment. In the third experiment, mechanical scarification of 13-month-old seeds from the southern ecozone was combined with chemical treatments using sulfuric acid, gibberellic acid, or ethylene. For all three ecozones together, intact fresh seeds had much lower (0.6% to 2.5%) germination than either seeds with their pericarp removed (78% to 82%) or bare nuts (pericarp and endocarp removed; 73% to 85%). Percentage germination increased significantly from the northern to the southern ecozone, particularly for bare nuts ( P<0.002). Soaked seeds had higher germination than did unsoaked seeds ( P<0.0001) for both the fresh and the older seeds. The average for the treatments yielding the highest germination of the 13-month-old southern ecozone seeds (66%) was 25% lower than it was for the freshly-collected southern ecozone seeds (91%). The highest germination (85%) for freshly-collected seeds (all ecozones) was obtained with mechanically-scarified seeds soaked in water for 3 days. For intact 13-month-old seeds, the sulfuric acid treatment resulted in 28.3% germination and was the only treatment which resulted in any germination of intact seeds. The 13-month-old mechanically scarified seeds treated with either gibberellic acid or ethylene had higher germination (57% for both) than mechanically scarified seeds treated either with sulfuric acid or not chemically treated (40% and 26.5%, respectively). Thus, it appears that the impermeability of the pericarp to water and oxygen, the need to physiologically activate the embryo with a water-soaking treatment and, in older seeds, a lowered physiological capacity of the embryo all constrained germination rates in older doum palm seeds.