Seed size and presence of thorns in Caryocar brasiliense on seedling emergence

Commercial propagation of pequizeiro, which stands out among the main native fruits of the Cerrado region for its high economic potential, has been done by seeds, despite their erratic germination. The objective of this study was to evaluate the effect of seed size and presence of thorns on the endocarp on seedling emergence of pequizeiro in the field. Seeds were collected in a pequizeiro commercial area in Canarana-MT, Brazil. Due to availability, 2,353 thorny seeds (3 sizes) and 106 seeds without thorns (medium sized) were tested. Thorny seeds were classified as large ­ longer than 50 mm; medium ­ between 40 and 50 mm; small ­ less than 40 mm. Seedling emergence started after 50 days in all seed categories, extending up to 100 days in the large seeds and to about 1 year after sowing in the small and medium sized ones. Small seeds showed a lower rate and speed of emergence compared to the others. Large seeds showed higher emergence speed compared to the medium ones. The presence of thorns did not affect seedling emergence. These results indicate the advantages of pequizeiro seed classification for sowing purposes.

Effective temperature for overcoming dormancy of 'Fuyu' persimmon tree buds

The objective of this study was to evaluate the effective temperature for overcoming the dormancy of 'Fuyu' persimmon tree buds. Stem samples were collected three times between 2013 and 2014. Stems were maintained in a climate incubator chamber at 3, 6, 9, and 12 °C. For each temperature, five numbers of additional chilling hours (CH) (0, 240, 384, 528, and 672 CH) were studied. The experimental design was completely randomized in a 5 × 4 factorial design (chilling hours × temperatures) with four replications with 10 cuttings. The maintenance of branches at cold temperatures from 3 to 12 °C intensified endodormancy of the buds when the plants were at the beginning of endodormancy. The most effective temperatures for overcome dormancy when the buds were in transition from paradormancy to endodormancy were from 3 to 6 °C. When the buds were already in endodormancy, temperatures of 3, 6, 9, and 12 °C were effective for the accumulation of cold and overcoming dormancy. The increase in the number of chilling hours from 3 to 12 °C induced budburst and the temperature of 12 °C was able to slowly induce and overcome bud dormancy.

Light quality and dormancy overcoming in seed germination of Echium plantagineum L. (Boraginaceae) / Qualidade da luz e superação de dormência na germinação de sementes de Echium plantagineum L. (Boraginaceae)

Abstract Light is considered a factor that influences the seed germination of many weed species, and it can signal whether the environmental conditions are favorable or are not favorable for germination. We aimed to study if there is an influence of light quality and dormancy overcoming in seed germination of Echium plantagineum L. We carried out a 2 x 6 factorial experiment, with and without dormancy overcoming with potassium nitrate followed by immersion in gibberellic acid; six light qualities, obtained through the light filters: blue, green, red, far-red, white light and absence of light. The evaluations performed were germination speed index (GSI), average germination time (AGT), germination at the four and 14 days after seeding (DAS), accumulated germination and relative frequency of germination. We observed significant interaction among the light qualities and seed dormancy overcoming or not for the studied variables. There was no significant effect of light qualities, in the evaluated variables, when performing dormancy overcoming, presenting germination above 90% in all the light qualities. However, without dormancy overcoming, we observed greater GSI, germination at four and 14 DAS for the red light filter with 5, 4, 29 and 45%, respectively. When the seeds were submitted to the absence of light, and without dormancy overcoming, there was only 7% of germination at 14 DAS. The seeds of E. plantagineum presented greater germination under incidence of red light, without dormancy overcoming, being classified as preferably positively photoblastics, provided that the dormancy is not overcome.

Resumo A luz é considerada um fator que influencia a germinação das sementes de muitas espécies de plantas daninhas, podendo sinalizar se as condições ambientais são favoráveis ou não para a germinação. Objetivou-se estudar se há influência da qualidade da luz e superação de dormência na germinação de sementes de Echium plantagineum L. Realizou-se um experimento fatorial 2 x 6, com e sem superação de dormência com nitrato de potássio seguido pela imersão em ácido giberélico; seis qualidades de luz, obtidas através de filtros de luz: azul, verde, vermelho, vermelho-distante, luz branca e ausência de luz. As avaliações realizadas foram índice de velocidade de germinação (IVG), tempo médio de germinação (TMG), germinação aos quatro e 14 dias após a semeadura (DAS), germinação acumulada e frequência relativa de germinação. Observou-se interação significativa entre as qualidades de luz e a superação ou não de dormência das sementes para as variáveis estudadas. Não houve efeito significativo das qualidades de luz, nas variáveis avaliadas, ao realizar superação de dormência, apresentando germinação acima de 90% em todas as qualidades de luz. Todavia, sem superação de dormência, observou-se maior IVG, germinação aos quatro e 14 DAS para o filtro de luz vermelha com 5,4, 29 e 45%, respectivamente. Quando as sementes foram submetidas à ausência de luz, e sem superação de dormência, houve apenas 7% de germinação aos 14 DAS. As sementes de E. plantagineum apresentam maior germinação sob incidência de luz vermelha, sem superação de dormência, sendo classificadas como fotoblásticas positivas preferenciais, desde que não seja superada a dormência.

Dormancy of Floral Buds of Rabbiteye Blueberry in a Mild Winter Climate

Abstract Blueberry is an important fruit crop, with many health benefits. Despite its importance, much remains to be studied concerning the dormancy dynamics in rabbiteye cultivars growing in a mild winter climate. In this research, the dormancy in blueberry, rabbiteye cultivars 'Bluegem', 'Climax', 'Delite', and 'Powderblue', was studied in a mild winter region. The single-node cuttings biological test and the evaluation of the hydric status were performed in dormant winter reproductive buds. These experiments were performed during fall and winter in one year (2016). Moreover, chilling hours under or equal to 7.2 ºC were measured, and chill units were calculated according to Utah Model [1], Modified Utah Model [2], and Blueberry Model [3]. In conclusion, the four cultivars showed a similar pattern, revealing a dormant state in the initial sampling dates and a released dormancy in the final treatments, showing the decrease of dormancy in June and July. However, Delite was earlier than the other cultivars. Bluegem and Delite required 134.0 chilling hours, 127.0 chill units (Utah Model), 198.5 chill units (Modified Utah Model), and 971.5 chill units (Blueberry Model) for 50% of their green tip buds reach the opened bud stage. Climax required 44.0, -11.0, 56.5, and 440.5, respectively. And Powderblue required 44.0, 5.5, 77.0, and 725.0 respectively. This study can bring some insights into crop management and production of this important fruit crop, especially in a global climate-changing scenario, related to flowering and dormancy control, as well as helping to select suitable cultivars to a region, concerning chilling requirements.

Transcriptome analysis of seed embryo in dormancy and dormancy release state of Thesium chinense / 中国中药杂志

We used exogenous GA_3 to break the seed dormancy of Thesium chinense. We used high-throughput sequencing technology was used to sequence the transcriptome of dormant seed embryos and dormancy breaking seed embryos of Th. chinense, and the data was analyzed bioinformatically and systematically. The results showed that exogenous GA_3 could effectively break the seed dormancy of Th. chinense; 73 794 up-regulated genes and 42 776 down regulated genes were obtained by transcriptome sequencing; 116 570 diffe-rential genes were annotated by GO function to GO items such as metabolism process, cell process, cell, cell component, binding and catalytic activity. A total of 133 metabolic pathways were found by Pathway analysis of 26 508 differentially expressed genes. In the process of dormancy release, DEGs were mainly enriched in translation, carbohydrate metabolism, folding, classification, degradation and amino acid metabolism. Based on the annotation results in KEGG database, 20 metabolic pathways related to dormancy release were found. Dormancy release of Th. chinense seeds is a complex biological process, including cell morphology construction, secondary metabolite synthesis, sugar metabolism and plant signal transduction, among which plant hormone signal transduction is one of the key factors to regulate dormancy release. The results of qRT-PCR showed that the sequencing results were consistent with the actual results.

Identification and differential expression of miRNA related to seed dormancy of Paris polyphylla var. chinensis / 中国中药杂志

The purpose of this study was to explore the expression pattern of miRNA in the process of embryo dormancy and provide a reference for the mechanism of regulating seed dormancy and germination by miRNA. We used high-throughput sequencing technology, bioinformatics analysis and real-time fluorescent quantitative PCR(qPCR) technology to sequence, screen and identify miRNAs of dormant and dormant embryos. The results showed that there were 23 811 977, 24 276 695, 20 611 876 and 20 601 811 unique sequences in the four sample libraries during the period of dormancy and dormancy release. MiRNAs are mainly distributed between 21 and 24 nt, among which the length of 24 nt occurred most frequently. A total of 31 known miRNAs were identified, belonging to 13 different families. 93 new miRNAs were predicted by bioinformatics software. Ten miRNAs(mir156 a-5 p, mir160 a-5 p, mir160 h-1, mir169 a-5 p, mir157 d, mir159 a-1, mir395-3, mir156 f-5 p, mir156-2 and mir171 a-3 p) were screened out. In this study, 10 miRNAs related to seed dormancy release were identified. The target genes mainly involved carbohydrate metabolism, plant hormone signal transduction, cell division and growth. The results of qRT-PCR showed that the sequencing results were consistent with the actual results.

Germination and seed conservation of a pioneer species, Tecoma stans (Bignoniaceae), from tropical dry forest of Colombia / Germinación y conservación de semillas de la especie pionera, Tecoma stans (Bignoniaceae), del bosque seco tropical de Colombia

Abstract Seed germination and seed longevity under different environmental conditions are fundamental to understand the ecological dynamics of a species, since they are decisive for its success within the ecosystem. Taking this into account, seed germination and seed storage behavior of a pioneer species of tropical dry forest (Tecoma stans) were studied in the laboratory, to establish the effect of different environmental conditions on a local tree population. Two seed lots collected in July 2011, from Cali (Colombia), were evaluated under three alternating temperatures (20/30, 20/25, 25/30 ºC; 16/8 h) and four light qualities (12-hour white light photoperiod, darkness, and 15 minutes of red light -R and far red light -FR). Final germination was recorded for all treatments; for white light treatment the daily germination was recorded to calculate mean germination rate, mean germination time, and two synchronization indices. To assess the effect of light quality on physiological variables, a destructive germination test was carried out. For this test, another seed lot was evaluated under the same light conditions using an alternating temperature of 20/30 °C - 16/8 h, recording germination during six days for every treatment. In addition, seeds were stored at two different moisture contents (7.7, 4.1 %) and three storage temperatures (20, 5, -20 ºC), during two time periods (one and three months); a seed germination test was conducted for each treatment. Four replicates of 35 seeds per treatment were used for all experiments. Germination was high (GP > 90 %) with all alternating temperatures under white light, whereas under R, FR, and darkness germination was evenly successful at low temperatures, but at higher temperature, half of the seeds entered into secondary dormancy (GP= 45-65 %). However, mean germination rate and synchronization under R and FR decreased significantly in comparison to white light treatment and, consequently, mean germination time increased. Seed storage behavior of this species is orthodox due to the high germination (GP > 90 %) obtained under all treatments. In conclusion, T. stans seeds have a negative germination response at high incubation temperatures in the absence of white light, entering into a secondary dormancy. In contrast, an environment with a lower temperature and without white light delays the germination, but at the end seeds are able to reach the same germination values. This seed dependence on incident light in limiting conditions suggests a physiological mechanism on the seed tissues of this species, probably mediated by phytochromes. Finally, the orthodox seed storage behavior of T. stans is a reason to include this species in ex situ seed conservation programs for restoration and recovery of the tropical dry forest; however, long-term studies should be conducted in order to evaluate the maintenance of this characteristic throughout longer periods of time. Rev. Biol. Trop. 66(2): 918936. Epub 2018 June 01.

Resumen La germinación y la longevidad de las semillas de una especie bajo diferentes condiciones ambientales son fundamentales para las dinámicas ecológicas de una especie, debido a que son decisivas en el éxito de la misma en un ecosistema. Teniendo en cuenta esto, se estudió la germinación y el comportamiento en el almacenamiento de las semillas de una especie pionera de bosque seco tropical (Tecoma stans) a nivel de laboratorio, para establecer el efecto de diferentes condiciones ambientales en una población local de árboles. Dos lotes de semillas recolectados en julio 2011, de Cali (Colombia), se evaluaron a tres temperaturas alternadas (20 / 30, 20 / 25, 25 / 30 °C; 16 / 8 h) y cuatro calidades de luz (fotoperiodo de 12 horas de luz blanca, oscuridad, y 15 minutos de luz roja -R y roja lejana -RL). Se registró la germinación final para todos los tratamientos; para el tratamiento de luz blanca se registró la germinación diaria para calcular la tasa media de germinación, el tiempo medio de germinación y dos índices de sincronización. Para evaluar el efecto de la calidad de luz sobre las variables fisiológicas, se realizó una prueba de germinación destructiva. Para esta prueba, otro lote de semillas fue puesto a las mismas condiciones de luz usando una temperatura alternada de 20 / 30 °C - 16 / 8 h, registrando la germinación durante seis días para cada tratamiento. Además, se almacenaron semillas a dos contenidos de humedad (7.7, 4.1 %) y a tres temperaturas de almacenamiento (20, 5, -20 °C), durante dos periodos de tiempo (uno y tres meses); se realizó una prueba de germinación a cada tratamiento. Cuatro repeticiones de 35 semillas por cada tratamiento se usaron en cada experimento. La germinación fue alta (PG > 90 %) en todas las temperaturas alternadas con luz blanca, mientras que en los tratamientos de luz R, RL y en oscuridad, la germinación fue igualmente exitosa a bajas temperaturas, pero a temperaturas más altas la mitad de las semillas entraron en latencia secundaria (PG= 45-65 %). Sin embargo, la tasa media de germinación y la sincronización en R y RL disminuyeron significativamente en comparación con el tratamiento de luz blanca y consecuentemente el tiempo medio de germinación aumentó. El comportamiento de las semillas de T. stans en el almacenamiento es ortodoxo debido a la alta germinación obtenida (PG > 90 %) en todos los tratamientos. En conclusión, las semillas de T. stans tienen una respuesta germinativa negativa a temperaturas de incubación alta en ausencia de luz blanca, donde entran a latencia secundaria. En contraste, un ambiente con baja temperatura y sin luz blanca retrasa la germinación, pero al final las semillas son capaces de alcanzar los mismos valores de germinación. Esta dependencia de las semillas a la luz incidente en condiciones limitantes sugiere la presencia de un mecanismo fisiológico en los tejidos de esta especie, probablemente mediado por fitocromos. Finalmente, el comportamiento ortodoxo de las semillas de T. stans en el almacenamiento abre la posibilidad de incluirla en programas de conservación ex situ para la restauración y recuperación del bosque seco tropical; no obstante, se deben llevarse a cabo pruebas más largas para evaluar el mantenimiento de esta característica por periodos de tiempo más largos.

Water absorption and method improvement concerning electrical conductivity testing of Acacia mangium (Fabaceae) seeds / Absorción de agua y optimización de métodos para medir la conductividad eléctrica en semillas de Acacia mangium (Fabaceae)

Abstract:Acacia is an important forest species of rapid growth whose seeds have tegument dormancy. In this work it was intended to characterize water absorption pattern after seed dormancy break, and to determine the amount of water, container size and the need of breaking the tegument dormancy, as to perform electrical conductivity test in small and large seeds of Acacia mangium (Fabaceae). The seeds were collected from 10, 8 and 6 years old trees established in poor yielding-capacity soils on savannah areas of Roraima, Brazil; seeds were classified in six lots concerning to seed size and tree age. Germination tests (50 seeds and four replications per lot) were carried out on germitest® paper maintained on gerbox at 25 °C. Imbibition was verified by seed weighing at different times (0, 2, 5, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96 and 120 hours). The electrical conductivity test consisted of three experiments, distinguished by the amount of water used and by the container size in which seeds were immersed. Seeds of A. mangium coming from 10 years old trees presented increased germination percent and germination speed than seeds of six-year old trees. Small seeds presented increased in electrical conductivity and water absorption until 120 hours when compared to large seeds. The immersion of seeds of A. mangium in 40 mL of distilled water into 180 mL plastic containers, after dormancy break, it is indicated for the determination of electrical conductivity test. The ratio of electrolytes by seed mass, after 24 hours of immersion in water, turns electrical conductivity test more accurate concerning A. mangium seeds. Rev. Biol. Trop. 64 (4): 1651-1660. Epub 2016 December 01.

Resumen:Acacia es una importante especie forestal de rápido crecimiento cuyas semillas presentan dormancia del tegumento. En este trabajo se caracterizó el patrón de absorción de agua después de la dormancia y se estableció la cantidad de agua, el tamaño del recipiente y la necesidad de ruptura del tegumento para poder medir la conductividad eléctrica en semillas pequeñas y grandes de Acacia mangium (Fabaceae). Las semillas fueron recolectadas de árboles de 6, 8 y 10 años, clasificadas en grandes o pequeñas y agrupadas en seis grupos. Para la prueba de germinación fueron utilizados cuatro repeticiones de 50 semillas de cada grupo, en papel germitest® a 25 °C. La imbibición se verificó con pesajes en los tiempos 0, 2, 5, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96 y 120 horas con semillas colocadas en papel. La prueba de conductividad eléctrica se realizó en tres experimentos diferenciados por la cantidad de agua utilizada y el tamaño del recipiente de inmersión de las semillas. Las semillas de árboles de 10 años de edad tienen un porcentaje de germinación más alto y mayor velocidad de germinación que semillas de árboles de seis años. Las semillas pequeñas tienen una mayor conductividad eléctrica y mayor porcentaje de absorción de agua en comparación con las semillas grandes, hasta 120 horas. La inmersión de semillas en 40 mL de agua destilada en recipientes plásticos de 180 mL, después de la dormancia, esta indicada para la determinación de la conductividad eléctrica. La lectura de electrolitos en semillas, después de 24 horas de inmersión en agua, hace más precisa la prueba de conductividad eléctrica de semillas de A. mangium.

Seed dormancy of Ochradenus baccatus (Resedaceae), a shrubby species from Arabian desert regions / Dormición de semillas de Ochradenus baccatus (Resedaceae), una especie arbustiva de las regiones desérticas arábicas

Abstract:Ochradenus baccatus is a perennial glycophyte growing in Middle East and it is one of the most important food sources for many animal species in desert regions. The aim of our study was to investigate the effects of seed storage, light, temperature and gibberellic acid (GA3) on germination of O. baccatus seeds. We also investigated the germination characteristics of O. baccatus seeds under different saline concentration and their capability to recover germination once they were transferred to distilled water. Seeds were stored at room temperature (20 ± 2 ºC) and at -18 ºC. Germination tests were conducted at alternating temperatures of 15/25, 20/30 and 25/35 ºC in either continuous darkness or photoperiod of 12-h dark/12-h light. To study the effect of GA3 on germination of O. baccatus seeds, freshly-collected seeds and stored seeds were soaked for 24 h in a GA3 water solution (1 g/L) before sowing. To assess the salinity tolerance during germination, seeds were germinated under different salinity levels (100, 200 and 400 mM NaCl). Stored seeds at room temperature and -18 ºC germinate equally well at different temperature regimes and light conditions. However, freshly matured seeds were not able to germinate even when they were treated with GA3. On the contrary, stored seeds at room temperature and -18 ºC treated with GA3 increase the final germination percentages. These results indicated that O. baccatus seeds have physiological dormancy and they need to be stored in order to break their dormancy. In the present study, one year of storage did not show a significant variation in germination between the two storage conditions assayed. Therefore, further research is needed to know about the maximum storage period for O. baccatus seeds under different storage conditions. Very few O. baccatus seeds (less than 5 %) germinated at the tested lowest concentration of NaCl. However, ungerminated seeds were able to germinate when salinity stress was alleviated. In conclusion, O. baccatus seeds have physiological dormancy, and seed storage (at room temperature and at -18 ºC) for one year is effective for breaking this dormancy. In addition, O. baccatus seeds present ability to remain viable in saline conditions and they will be able to germinate once the salinity level decrease. Rev. Biol. Trop. 64 (3): 965-974. Epub 2016 September 01.

ResumenOchradenus baccatus es un glicófito perenne que crece en oriente Medio y es una de las fuentes de alimentación más importantes para muchas especies animales de regiones desérticas. El objetivo de nuestro estudio fue investigar los efectos del almacenamiento de semillas, luz, temperatura y ácido giberélico (GA3) en la germinación de semillas de O. baccatus. También se ha investigado la germinación de semillas de O. baccatus bajo diferentes concentraciones salinas y su capacidad para recuperar la germinación una vez que fueron transferidas a agua destilada. Las semillas se conservaron a temperatura ambiente (20 ± 2 ºC) y a -18 ºC. Los ensayos de germinación se realizaron a temperaturas alternas de 15/25, 20/30 y 25/35 ºC bajo oscuridad continua o fotoperiodo de 12-h oscuridad/12-h luz. Para estudiar el efecto del GA3 en la germinación de semillas de O. baccatus, semillas recién recolectadas y semillas almacenadas se sumergieron durante 24 h en una solución acuosa de GA3 (1 g/L) antes de la siembra. Para evaluar la tolerancia a la salinidad durante la germinación, la semillas fueron germinadas bajo diferentes niveles de salinidad (100, 200 y 400 mM ClNa). Las semillas conservadas a temperatura ambiente y a -18 ºC germinaron igualmente bien en los diferentes regímenes de temperatura y condiciones de iluminación. Sin embargo, las semillas recién maduradas fueron incapaces de germinar incluso cuando se trataron con GA3. Por el contrario, las semillas almacenadas tratadas con GA3 incrementaron los porcentajes finales de germinación. Estos resultados indican que las semillas de O. baccatus tienen dormición fisiológica y necesitan ser almacenadas para romperla. En este estudio, un año de conservación no supuso una variación significativa en la germinación entre las dos condiciones de conservación ensayadas. Por lo tanto, se precisan investigaciones adicionales para conocer cuáles son los periodos máximos de almacenamiento de semillas de O. baccatus bajo diferentes condiciones de conservación. Muy pocas semillas de O. baccatus (menos del 5 %) germinaron a la concentración más baja de ClNa. Sin embargo, las semillas no germinadas fueron capaces de germinar cuando el estrés salino fue aliviado. En conclusión, las semillas de O. baccatus tienen dormición fisiológica y el almacenamiento de las mismas (a temperatura ambiente y a -18 ºC) durante un año es eficaz para romper dicha dormición. Además, las semillas de O. baccatus presentan capacidad para permanecer viables en condiciones salinas y serán capaces de germinar una vez que el nivel de salinidad disminuya.

Seed colour affects light and temperature requirements during germination in two Lotus species (Fabaceae) of the Arabian subtropical deserts / El color de la semilla afecta los requerimientos de luz y temperatura durante la germinación en dos especies de Lotus (Fabaceae) de los desiertos subtropicales árabes

AbstractHeterogeneity in seeds mostly occurs due to physiological, environmental and genetic factors, and these could affect seed dormancy and germination. Therefore, the aim of our study was to assess the effect of seed colour on germination behavior. For this, both light and temperature requirements were assessed in Lotus glinoides and Lotus halophilus (Fabaceae) from the hyper-arid deserts of the United Arab Emirates. Germination was assessed in terms of both final germination level (percentage) and germination rate, as expressed by Timson’s germination velocity index. Lotus glinoides produces black and yellow-colored seeds, and L. halophilus produces green and yellow seeds. Different seed lots were germinated in both light and darkness at different temperatures. Yellow seeds of the two species attained significantly lower germination, compared to black and green seeds. There was no specific light or temperature requirements for the germination of the two coloured seeds of L. glinoides; the effect of interactions between seed colour and both light and incubation temperature, were not significant on the final germination percentage. in L. halophilus, green seeds germinated significantly more in both light and darkness at lower temperatures (15/25 °C) and in light at higher temperatures (25/35 °C), compared to yellow seeds. Yellow seeds germinated faster, compared to black at 15/25 °C in L. glinoides and compared to green seeds at 15/25 °C and 25/35 °C in L. halophilus. Seed colour variation, at least in L. halophilus, could be a survival strategy that would determine the time of germination throughout the year in the unpredictable desert environment. Rev. Biol. Trop. 64 (2): 483-492. Epub 2016 June 01.

ResumenLa heterogeneidad en las semillas se produce principalmente debido a factores fisiológicos, genéticos y ambientales, y esto podría afectar latencia de las semillas y la germinación. Por lo tanto, el objetivo de nuestro estudio fue evaluar el efecto del color de la semilla en el comportamiento de la germinación. Para ello, tanto los requisitos de luz y temperatura fueron evaluados en Lotus glinoides y Lotus halophilus (Fabaceae) desde los desiertos hiper-árida de los Emiratos Árabes Unidos. La germinación se evaluó en términos de nivel final de germinación (porcentaje) y la tasa de germinación, expresado por el índice de velocidad de germinación de Timson. L. glinoides produce semillas negro y de color amarillo, y L. halophilus produce semillas verdes y amarillas. Los diferentes lotes de semillas fueron germinadas en luz y oscuridad a diferentes temperaturas. Semillas amarillas de las dos especies alcanzaron significativamente menor germinación, en comparación con las semillas negras y verdes. No había requisitos específicos de luz o temperatura para la germinación de las semillas de dos colores de L. glinoides; el efecto de las interacciones entre color de la semilla y la luz y la temperatura de incubación, no fueron significativas en el porcentaje final de germinación. En L. halophilus, semillas verdes germinados significativamente más en la luz y la oscuridad a temperaturas más bajas (15/25 °C) ya la luz a temperaturas más altas (25/35 °C), en comparación con semillas amarillas. Semillas amarillas germinaron más rápido, en comparación con el negro a 15/25 °C en L. glinoides y en comparación con semillas verdes a 15/25 °C y 25/35 °C en L. halophilus. La variación del color de la semilla, al menos en L. halophilus, podría ser una estrategia de supervivencia que determinaría el momento de la germinación durante todo el año en el entorno del desierto impredecible.

Floral induction, production and seed quality of parsley cultivars as influenced by plants vernalization periods / Indução floral, produção e qualidade de sementes de cultivares de salsa em função de períodos de vernalização das plantas

In the production of parsley (Petroselinum crispum) seeds is recommended the cultivation in locations of low temperatures to permit the emission of floral stalk. The study aimed to verify the effect of vernalization on floral induction, production and quality of parsley seeds. Ten plants of three cultivars (Caipira, Chacareira and Lisa Grande Portuguesa (O. Enke)) grown in pots for six months were submitted to vernalization at 5 °C for 0, 15, 30 and 45 days. After treatment, the plants were transferred to greenhouse and evaluated for period and flowering percentage, seed yield per plant and seed quality. The seed quality was evaluated by weight of a thousand seeds, germination (percentages of normal and abnormal seedlings, dormant and dead seeds), first count of germination, accelerated aging, dormancy after accelerated aging, seedling emergence in the field and seed water content before and after accelerated aging. It was concluded that the vernalization does not promotes floral induction and production of parsley seeds. For Lisa Grande Portuguesa (O. Enke) cultivar, the vernalization of the plant for 30 days enables the production of seed with high germination and vigor. Parsley seeds dormancy can be caused by plants vernalization periods between 30 and 45 days depending on the cultivar, followed by the exposure of the seeds to the conditions of high temperature and relative humidity of the air (41 °C/100%, UR/72 h).

Na produção de sementes de salsa (Petroselinum crispum) recomenda-se o cultivo em locais de baixas temperaturas para possibilitar a emissão do pendão floral. O objetivo do trabalho foi verificar o efeito da vernalização (0, 15, 30 e 45 dias) na indução floral, produção e qualidade de sementes de salsa. Dez plantas de três cultivares (Caipira, Chacareira e Lisa Grande Portuguesa (O. Enke)) cultivadas em vasos por seis meses, foram submetidas à vernalização a 5 °C por 0, 15, 30 e 45 dias. Após o tratamento, foram transferidas para casa-de-vegetação e avaliadas quanto à época e porcentagem de florescimento, produção de sementes por planta e qualidade das sementes. A qualidade foi avaliada por meio da determinação da massa de mil sementes, teste de germinação (porcentagens de plântulas normais, anormais, sementes dormentes e mortas), primeira contagem de germinação, teste do envelhecimento acelerado, dormência após o envelhecimento acelerado, emergência de plântulas em campo, teor de água das sementes antes e após o envelhecimento acelerado. Concluiu-se que a vernalização não promoveu a indução floral e a produção de sementes. Para a cultivar Lisa Grande Portuguesa (O. Enke), a vernalização da planta por 30 dias possibilitou a produção de sementes com maior germinação e vigor. A dormência das sementes pode ser causada pela vernalização das plantas por períodos entre 30 e 45 dias, dependendo da cultivar, seguida de exposição das sementes produzidas a condições de altas temperaturas e umidade relativa (41 °C/100%UR/72h).

Efeito de tratamento térmico na superação de dormência de sementes de Passiflora suberosa L / Effect of thermal treatment on overcoming seeds dormancy of Passiflora suberosa L

O valor ornamental das passifloras é atribuído especialmente à exuberância das flores, com suas formas, cores e tamanhos diversificados. Entre as espécies de Passiflora que apresentam potencial ornamental destaca-se a Passiflora suberosa L., que ocorre em regiões de cerrados, de florestas pluviais montanhosas, submontanhosas e de restingas. Objetivou-se com este trabalho avaliar o efeito de diferentes temperaturas e tempos de imersão em água, na germinação de sementes de P. suberosa. O delineamento experimental utilizado foi o inteiramente casualizado, com 11 tratamentos, gerados da combinação de cinco temperaturas (30, 40, 50, 60 e 70 ºC), dois tempos de imersão das sementes (5 e 15 minutos) em água aquecida e uma testemunha (sem tratamento), com quatro repetições, sendo 25 sementes por parcela. As características avaliadas foram: porcentagem de germinação, índice de velocidade de germinação, primeira contagem e porcentagem acumulada de germinação. Os resultados obtidos e analisados permitiram concluir que o melhor tratamento para superação de dormência é imersão em água destilada a 50 ºC por 5 minutos.

The ornamental value of passifloras is attributed especially to the exuberance of flowers, their shapes, colors and sizes varied. Among the species of Passiflora that have ornamental potential can cite the Passiflora suberosa L. occurring in regions of cerrados, rainforests to mountain, sub-mountainous and restingas. Ornamental value of Passiflora species is attributed especially to the exuberance of flowers, their shapes, colors and varied sizes. But there are many obstacles involving the process of conservation of these species, one of them is seed germination. Therefore, the objective of this study was to evaluate the effect of different temperatures and times of immersion in water germination of P.suberosa. The experimental design was a completely randomized design with 11 treatments, generated from the combination of five temperatures (30°C, 40°C, 50°C, 60°C and 70°C), two times of soaking seeds (5 minutes and 15 minutes) in heated water and a control (untreated) with four replications and 25 seeds per plot. The characteristics evaluated were: germination percentage, speed of germination, first count and cumulative percentage of germination. The results showed that for overcoming seeds dormancy is soaking in distilled water at 50ºC for 5 minutes.

Dormancy-breaking requirements of Sophora tomentosa and Erythrina speciosa (Fabaceae) seeds / Dormancy-breaking requirements of Sophora tomentosa and Erythrina speciosa (Fabaceae) seeds

The physical dormancy of seeds has been poorly studied in species from tropical forests, such as the Atlantic Forest. This study aimed to examine the effect of moderate alternating temperatures on breaking the physical dormancy of seeds, the morphoanatomy and histochemistry of seed coats, and to locate the structure/region responsible for water entrance into the seed, after breaking the physical dormancy of seeds of two woody Fabaceae (subfamily Faboideae) species that occur in the Brazilian Atlantic Forest: Sophora tomentosa and Erythrina speciosa. To assess temperature effect, seeds were incubated in several temperature values that occur in the Atlantic Forest. For morphological and histochemical studies, sections of fixed seeds were subjected to different reagents, and were observed using light or epifluorescence microscopy, to analyze the anatomy and histochemistry of the seed coat. Treated and non-treated seeds were also analyzed using a scanning electron microscope (SEM) to observe the morphology of the seed coat. To localize the specific site of water entrance, the seeds were blocked with glue in different regions and also immersed in ink. In the present work a maximum temperature fluctuation of 15ºC was applied during a period of 20 days and these conditions did not increase the germination of S. tomentosa or E. speciosa. These results may indicate that these seeds require larger fluctuation of temperature than the applied or/and longer period of exposition to the temperature fluctuation. Blocking experiments water inlet combined with SEM analysis of the structures of seed coat for both species showed that besides the lens, the hilum and micropyle are involved in water absorption in seeds scarified with hot water. In seeds of E. speciosa the immersion of scarified seeds into an aniline aqueous solution showed that the solution first entered the seed through the hilum. Both species showed seed morphological and anatomical features for seed coats of the subfamily Faboideae. Lignin and callose were found around all palisade layers and the water impermeability and ecological role of these substances are discussed in the work.

Requisitos para romper la latencia en semillas de Sophora tomentosa y Erythrina speciosa (Fabaceae). La latencia física de las semillas ha sido poco estudiada en las especies de los bosques tropicales, como el bosque atlántico. Este estudio tuvo como objetivo examinar el efecto de las temperaturas moderadas alternantes en romper la latencia física de las semillas, la anatomía y la histoquímica de la cubierta de las semillas, y la localización de la estructura o región responsable de la entrada de agua, después de romper la latencia física de las semillas de Sophora tomentosa y Eythrina speciosa, dos especies leñosas de Fabaceae (subfamilia Faboideae) que presentes en el bosque atlántico de Brasil. Para cumplir con el primer objetivo se incubaron las semillas a varias temperaturas que se dan en el bosque atlántico. Para los estudios morfológicos e histoquímicos se fijaron secciones de semillas sometidos a diferentes reactivos y se observaron usando luz o microscopía de epifluorescencia para analizar la anatomía y la histoquímica de la cubierta de la semilla. Semillas tratadas y no tratadas se analizaron también usando un microscopio electrónico de barrido (MDB) o microscopio estereoscópico (ME) para observar la morfología de la cubierta de la semilla. Para localizar el sitio específico de la entrada de agua, las semillas fueron bloqueadas con pegamento en diferentes regiones y también sumergidas en tinta. En el presente trabajo se aplicó una fluctuación de temperatura máxima de 15°C durante un período de 20 días y estas condiciones no aumentó la germinación de S. tomentosa o E. speciosa. Estos resultados pueden indicar que estas semillas requieren mayor fluctuación de la temperatura que la aplicada y/o un período más largo de exposición a la fluctuación de la temperatura. Experimentos de bloqueo de entrada de agua combinada con el análisis de las estructuras de la cubierta de la semilla para ambas especies (SEM) mostró que, a pesar de la lente, el hilio y micropilo están implicados en la absorción de agua en las semillas escarificadas con agua caliente. En las semillas de E. speciosa la inmersión de semillas escarificadas en una solución acuosa de anilina mostró que la solución entró por primera vez a la semilla a través del hilio. Ambas especies mostraron características morfológicas y anatómicas de semillas con cubierta de la subfamilia Faboideae. La lignina y callosa se encontraron alrededor de todas las capas de empalizada y la impermeabilidad al agua y en el trabajo se discute el papel ecológico de estas sustancias.

Superação de dormência em sementes de Bombax malabaricum D. C. (Malvaceae) / Dormancy breaking in seeds of Bombax malabaricum D. C. (Malvaceae)

RESUMOA espécie Bombax malabaricum, popularmente conhecida por paineira-vermelha, apresenta metabólitos secundários de interesse medicinal. Como outras espécies da família Malvaceae, suas sementes possuem dormência tegumentar, o que dificulta sua propagação sexuada. Assim, o presente trabalho objetivou superar a dormência de sementes de B.malabaricum por métodos físicos e químicos. Os métodos utilizados na escarificação mecânica foram: abrasão do tegumento com lixa e corte com tesoura na região oposta ao hilo. Para a escarificação química foram utilizados: ácido clorídrico (HCl), ácido nítrico (HNO3), ácido sulfúrico (H2SO4), hidróxido de sódio (NaOH) e hidróxido de potássio (KOH) por um período de 30 minutos. Também houve imersão de sementes em 40 mg L-1 de GA3 pelo mesmo período. Foram utilizadas quatro repetições por tratamento, constituídas de 25 sementes por placa e conduzidas em Câmara de Germinação. Os dados obtidos foram utilizados para o cálculo da Germinabilidade, Índice de Velocidade de Germinação, Tempo Médio de Germinação, e Porcentagem de Sementes Deterioradas. O HNO3 mostrou-se como o melhor tratamento na variável Germinabilidade (83,5%), seguido do HCl (71,5%) e das técnicas de escarificação mecânica, com lixa (71,5%) e tesoura (67,5%). O HNO3também apresentou o menor número de sementes deterioradas (3,5%); o H2SO4 foi o tratamento que mais causou danos às sementes (36,5%).

ABSTRACTThe species Bombax malabaricum, popularly known as red-cotton tree, presents secondary metabolites of medicinal interest. Like other species of the Malvaceae, their seeds have tegumentary dormancy, which hinders their sexual propagation. Thus, this study aimed to break the dormancy of B. malabaricum through physical and chemical strategies. For mechanical scarification of the seeds it were employed: abrasion of the tegument with sandpaper and cut with scissors in the region opposite to the hilum. For chemical scarification: hydrochloric acid (HCl), nitric acid (HNO3), sulphuric acid (H2SO4), sodium hydroxide (NaOH) and potassium hydroxide (KOH) for a period of 30 minutes. The seeds were also subjected to immersion in 40 mg L-1 of GA3 for the same period. Four replicates of 25 seeds were used for each treatment and then they were conducted for calculation in a B.O.D. germination Chamber. The results obtained were applied in order to calculate: Germination, Germination Speed Index, Average Time of Germination and Percentage of Damaged Seeds. The HNO3proved to be the best treatment in the Germination trials (83.5%), followed by the HCl (71.5%) and the mechanical scarification techniques with sandpaper (71.5%) and scissors (67.5%). The HNO3 also showed the lowest percentage of damaged seeds (3.5%); The H2SO4 was the treatment that caused more damage to the seeds (36.5%).

Study on winter dormancy of Thesium chinense and its phenological phase / 中国中药杂志

In order to explore reasonable artificial cultivation pattern of Thesium chinense, the biological characteristics and nutrients change in the process of winter dormancy of T. chinense was studied. The phenological period of T. chinense was observed by using fixed-point notation and the starch grains changes were determined dynamically by PAS-vanadium iron hematoxylin staixjing method. Soluble sugar and starch content were measured by anthrone-sulfuric acid method and amylase activity was determined by DN'S method. The results showed that the normal life cycle of T. chinense was two years. T. chinense was growing by seed in the first year, but growing by the root neck bud in the second year. During the process of dormancy, starch and soluble sugar could mutual transformation in different periods. T. chinense had sufficient carbohydrate to maintain growth and also a lot of small molecules to improve their ability to fight against adversity.

Effects of low temperature on dormancy breaking and growth after planting in bulbs of Tulipa edulis / 中国中药杂志

The effect of low temperature storage on dormancy breaking, sprouting and growth after planting of Tulipa edulis was studied. The results showed that starch content and activity of amylases significantly decreased during 10 weeks of cold storage, soluble protein content raised at first then decreased, and the peak appeared at the 6th week. However, total soluble sugar content which in- creased slowly at first than rose sharply and reducing sugar content increased during the storage duration. The bulbs with cold storage treatment rooted in the 6th week, which was about 2 weeks earlier than room temperature storage, but there were less new roots in the late period of storage. After stored at a low temperature, bud lengths were longer than that with room temperature treatment. Cold storage treatment could promote earlier emergence, shorten germination time, prolong growth period and improve the yield of bulb, but rarely affect the emergence rate. It was not beneficial to flowering and fruiting. The results indicated that 6-8 weeks of cold storage was deemed to be the key period of dormancy breaking preliminary.

Effect of seed coat on the seed germination and seedling development of Calophyllum brasiliense Cambess. (Clusiaceae) / Efeito do envoltório na germinação da semente e no desenvolvimento de plântulas de Calophyllum brasiliense Cambess. (Clusiaceae)

This work aimed to study the effect of the Calophyllum brasiliense seed coat on the seed germination process. To this end, three experiments were conducted in laboratory, greenhouse and screenhouse. From a total of six treatments, five are related to the seed coat (mechanical scarification; mechanical scarification followed by 2 hours in water, chemical scarification, hot water immersion and complete seed coat removal) and one control. Laboratory and greenhouse experiments were conducted in a completely randomized design (CRD). Screenhouse experiment was conducted in a completely randomized block design (RBD). We evaluated the total percentage, the speed index and the average time of germination or emergence. Data were subjected to analysis of variance and means compared by LSD test, at 5%. Under the conditions of this work, it was possible to infer that, in laboratory, mechanical scarification followed by 2 hours in water increases the proportion and germination speed index (GSI), in the greenhouse, the complete seed coat removal increases the percentage and emergence speed index (ESI), and in the screenhouse, mechanical scarification followed by 2 hours in water and chemical scarification presented the best results. The average germination time was not significantly different in the three experiments evaluated.

Objetivou-se com este trabalho estudar o efeito do envoltório da semente de Calophyllum brasiliense no processo de germinação. Foram montados três experimentos, sendo estes conduzidos em laboratório, casa de vegetação e telado. Avaliaram-se seis tratamentos, sendo cinco relacionados ao envoltório (escarificação mecânica; escarificação mecânica seguido por 2h em água; escarificação química; imersão em água quente; e retirada total do envoltório) e a testemunha. Os experimentos em laboratório e casa de vegetação foram conduzidos em delineamento inteiramente casualizado. No telado, o experimento foi conduzido em delineamento em blocos casualizados. Avaliaram-se a percentagem total; o índice de velocidade e o tempo médio de germinação ou emergência. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste t (LSD) a 5% de probabilidade. Foi possível inferir que no laboratório, a escarificação mecânica, seguido por 2h em água, aumenta a percentagem e o índice de velocidade de germinação (IVG); na casa de vegetação, a retirada total do envoltório aumenta a percentagem e o índice de velocidade de emergência (IVE); e no telado, a escarificação mecânica, seguida por 2h em água, e a escarificação química apresentam os melhores resultados. O tempo de germinação não apresentou diferença significativa nos três experimentos avaliados.

Seed germination of Agave species as influenced by substrate water potential

BACKGROUND: Plants of Agave spp. perform Crassulacean acid metabolism (CAM) and are highly drought-tolerant, but little is known concerning seed germination under low water availability. The aim of this study was to assess the effect of substrate water potential (ΨW) on seed germination and contrast hydrotime parameters of seven valuable and commercially-important Agave species from different geographical distributions and climatic regions of Mexico. Our hypothesis was that seed germination of Agave species is not affected by low water availability independently of seed biomass and the climate of their distribution area. RESULTS: Seed germination (at 25°C and in the dark) between 85 and 100% for all species occurred within 80 - 180 h at -0.03 MPa and 250 - 430 h at -1.0 MPa. Seed germination at -1.5 MPa declined to less than 50% (p < 0.05) for A. asperrima and A. cupreata but did not change significantly for A. americana var. marginata, A. lechuguilla and A. striata, although they showed the lowest mean base water potential (-2.01 to -2.64 MPa). Seed germination of 40% Agave species, from arid and semi-arid climates in this study, was not affected by the lower ΨW. CONCLUSION: Germination of seeds of Agave species is moderately affected by low water availability, is partially dependent of their ecological distribution, and is independent of seed mass.

Maturação fisiológica e dormência em sementes de sabiá (Mimosa caesalpiniifolia Benth) / Physiological maturity and dormancy in sabia (Mimosa caesalpiniifolia Benth) seeds

O estado de dormência surge durante o desenvolvimento da semente com a desidratação dos protoplastos do embrião e com a maturação do tegumento, que frequentemente possui permeabilidade seletiva. Assim, o estudo do processo de maturação das sementes é de vital importância para se determinar o ponto ideal da colheita de sementes, garantindo assim máxima produção e elevada qualidade fisiológica. O presente trabalho foi desenvolvido com o objetivo de avaliar o efeito de diferentes estádios de maturação fisiológica sobre a dormência, germinação e vigor de sementes de sabiá (Mimosa caesalpiniifolia Benth). O trabalho foi conduzido no Laboratório de Análise de Sementes do Departamento de Ciências Vegetais da Universidade Federal Rural do Semi-Árido. O delineamento estatístico utilizado foi inteiramente casualizado, em esquema fatorial 2x5 (com e sem quebra de dormência x cinco estádios de maturação), constituindo assim 10 tratamentos e quatro repetições. Foram avaliados o teor de água das sementes, a porcentagem de germinação, o índice de velocidade de germinação e a primeira contagem. Constatou-se diferença significativa para todas as variáveis estudadas. As sementes de sabiá tornam-se dormentes à medida que diminuem seu teor de água e amadurecem fisiologicamente. A maior qualidade fisiológica das sementes é obtida por ocasião da maturação e secagem, desde que processos de quebra de dormência sejam realizados. Pode-se obter elevada porcentagem de germinação com sementes colhidas de vagens com coloração marrom-clara sem tratamentos de superação da dormência.

The dormant state arises during seed development with dehydration of embryo protoplasts and tegument maturation, which often has selective permeability. Thus, the study of the process of seed maturation is vital to determine the optimal harvest of seeds, ensuring maximum yield and high physiological quality. The present work was to evaluate the effect of different maturation stages on physiological dormancy, germination and vigor in sabiá seeds (Mimosa caesalpiniifolia Benth). The work was conducted in the Laboratory of Seed Analysis, Department of Plant Sciences, Universidade Federal Rural do Semi-Árido. The statistical design was completely randomized in a 2x5 factorial arrangement (with and without breaking dormancy x five phases of maturity), thus constituting 10 treatments and four replications. We evaluated the water content of seeds, germination percentage, the rate of speed of germination and the first count. It found significant differences for all variables. The seeds of thrush become dormant decrease as its water content and mature physiologically. The highest vigor of the seed is obtained at the time of maturing and drying, since processes are performed dormancy. You can get high germination percentage of pods with seeds harvested with brownishclear without treatment break dormancy.

Superação de dormência em sementes de manjericão (Ocimum basilicum L. ) / Overcoming dormancy in seeds of basil (Ocimum basilicum L. )

O objetivo do trabalho foi avaliar a eficiência de tratamentos pré-germinativos na superação da dormência de sementes de manjericão, produzidas no Horto de Plantas Medicinais da Unimontes, em fevereiro de 2011. Foram realizadas as seguintes determinações para avaliação da qualidade fisiológica das sementes: teor de água, germinação, primeira contagem de germinação, emergência de plântulas e índice de velocidade de emergência. O delineamento experimental utilizado foi inteiramente casualizado com quatro repetições de 50 sementes por tratamento, sendo T1- testemunha; T2 - pré esfriamento das sementes em câmara tipo BOD sob temperatura de 10ºC por 4 dias; T3 - embebição das sementes em água destilada por 24 horas; T4 - embebição das sementes em solução contendo KNO3 a 0,2 % por 5 minutos e T5 - sementes submetidas em água destilada a temperatura de 70ºC por 5 minutos. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste Scott - Knott a 5% de probabilidade. O tratamento pré esfriamento em câmara tipo BOD a 10ºC por 4 dias reduz a dormência e promove incrementos na qualidade fisiológica das sementes do manjericão.

Aiming in order to assess the effectiveness of treatments to overcome dormancy in seeds of basil, an experiment was conducted at the Laboratory of Seed Analysis of Unimontes. Following determinations were performed to evaluate the physiological quality of seeds, water content, germination, first count germination, seedling emergence and emergence speed index. The experimental design was completely randomized design with four replications of 50 seeds per treatment, which consisted of: T1 - control, T2 - pre-cooling of the seed chamber BOD at a temperature of 10ºC for 4 days, T3 - soaking the seeds in water distilled for 24 hours, T4 - soaking the seeds in a solution containing 0,2% for 5 minutes and T5 - submitted seeds in distilled water at 70ºC for 5 minutes. Data were subjected to analysis of variance and the averages compared by Scott-Knott 5% probability. The pre-cooling treatment in BOD chamber at 10ºC for 4 days reduced dormancy and promotes increases in the physiological quality of seeds of basil.