Effect of EBR on Seed Germination， Seedling Growth and Key Enzyme Activities for Flavonoid Biosynthesis in Astragalus membranaceus var. mongholicus Under PEG-induced Drought Stress / 中国实验方剂学杂志

Objective:To study the effects of 24-epibrassinolide （EBR） at different concentrations on seed germination， seedling growth and key enzyme activities for flavonoid biosynthesis in <italic>Astragalus membranaceus </italic>var.<italic> mongholicus</italic> under polyethylene glycol （PEG）-induced drought stress， in order to provide theoretical reference for standardizing the drought-resistant cultivation techniques of <italic>A. membranaceus </italic>var.<italic> mongholicus</italic>. Method:The seeds of <italic>A. membranaceus </italic>var.<italic> mongholicus </italic>were soaked in EBR solution at different concentrations（0.001， 0.01， 0.1， 1， 10 μmol·L^-1） followed by foliar spraying to explore their effects on seed germination， seedling growth， photosynthesis， chlorophyll and malondialdehyde （MDA） contents， and key enzyme activities for flavonoid biosynthesis under drought stress induced by 20% polyethylene glycol （PEG）-6000. Result:Compared with the control（CK）group， PEG-induced drought stress led to an obvious decrease in germination potential， germination rate， germination index， vigor index， relative germination rate， plant height， root length， aboveground and root dry weight， net photosynthetic rate （<italic>Pn</italic>）， stomata conductance （<italic>Gs</italic>）<italic>， </italic>transpiration rate （<italic>Tr</italic>）， chlorophyll contents and chlorophyll a/b ratio， while a significant increase in intercellular carbon dioxide concentration （<italic>Gi</italic>）， MDA， flavonoids contents， and key enzyme activities for flavonoid biosynthesis such as phenylalanine ammonia lyase （PAL）. The treatment with exogenous EBR solution at the suitable concentration significantly enhanced the adaptation of <italic>A. membranaceus </italic>var.<italic> mongholicus </italic>seeds and seedlings to PEG-induced drought stress， manifested as significantly elevated germination potential， germination rate， germination index， vigor index， relative germination rate， plant height， root length， aboveground and root dry weight， <italic>Pn</italic>， <italic>Gs， Tr</italic>， chlorophyll a/b ratio， chlorophyll and flavonoids contents and key enzyme activities for flavonoid biosynthesis like PAL while lowered <italic>Ci</italic> and MDA contents. The optimal concentration of EBR solution was 0.1 μmol·L^-1. Conclusion:Exogenous EBR solution at the suitable concentration ameliorates the inhibitory effect of 20% PEG stress against seed germination and seedling growth of <italic>A. membranaceus </italic>var.<italic> mongholicus</italic>， reduces the oxidative damage in leaves， and improves the stress resistance to a certain extent by up-regulating the key enzyme activities and promoting flavonoid synthesis.

Seedling length and soybean seed vigor / Comprimento de plântulas e vigor de sementes de soja

ABSTRACT: The differentiation of seedling growth and development is the result of the vigor level of the seed lot. Because of this, knowing the seedling growth curve is essential for the evaluation of the seedling length test, to be carried out at the moment when any differences in vigor really manifest, thus being able to reduce the time of evaluation of the test. In this research, the objective was to determine the most efficient time interval to perform the seedling length test in soybean seeds, depending on the vigor levels. The evaluated characteristics were percentage of seed germination, first germination count, emergency, days for emergence, aerial, root and total length (evaluated every 12 hours), aerial, root and total dry mass in completely randomized design. High vigor seeds originated seedlings with higher growth rates (cm. h-1), with vigor being one of the factors that interfere in the seedling length test. After 96 hours of the seedling length test, there was a statistical differentiation between the three vigor levels tested. The soybean seedling length test between lots, with different vigor, can be performed 96 hours after sowing.

RESUMO: A diferenciação do crescimento e desenvolvimento das plântulas, é resultado do nível de vigor do lote das sementes. Em virtude disto, conhecer a curva de crescimento das plântulas é fundamental para que a avaliação do teste de comprimento de plântulas, seja realizada no momento em que realmente se manifestem as eventuais diferenças de vigor, podendo assim reduzir o tempo de avaliação do teste. No trabalho, o objetivo foi determinar o intervalo de tempo mais eficiente para realizar o teste de comprimento de plântula em sementes de soja, em função dos níveis de vigor. As características avaliadas foram germinação, primeira contagem de germinação, emergência, dias para emergência, comprimento de parte aérea, raiz e total (avaliados de 12 em 12 horas), massa seca de parte aérea, raiz e total em delineamento inteiramente casualizado. As sementes de alto vigor originaram plântulas com maiores taxas de crescimento (cm. h-1), sendo o vigor um dos fatores que interfere no teste de comprimento de plântulas. Após 96 horas do teste de comprimento de plântula ocorreu a diferenciação estatística entre os três níveis de vigor testados. O teste de comprimento de plântula de soja entre lotes, com vigor distinto, pode ser realizado 96 horas após a semeadura.

Modulated UV-B radiation invoking cytomorphological and biochemical aspects of a medicinal plant, Bhringraj (Eclipta alba (L.) Hassk.)

Aim: The current experimental work has been designed to study the effect of UV-B exposure on the seedling growth and meiotic consequences of Eclipta alba (L.) Hassk.Methodology: The seedlings were exposed to UV-B radiation for different time durations, i.e., 40, 80, 120 min along with control sets. UV-B irradiated seedlings along with respective controls were sown in the field and young floral buds were fixed in Carnoy’s fixative for 24 hrs and preserved in 90% ethanol for meiotic study. Results: Exposure of UV-B exposure resulted in various chromosomal aberrations like stickiness, laggards, bridges, unorientation, precocious, multivalents etc. Chromosomal stickiness was profound abnormality encountered at shorter duration (40 min) to UV-B exposure. The results revealed that UV-B exposure for shorter duration is quite beneficial to plant as it induces significant cytomorphological and biochemical variations. Interpretation: Shorter exposure to UV-B radiation induced certain beneficial traits in Eclipta alba. Since, Eclipta alba is a medicinally significant plant, hence, it is essential to improve their quantitative and qualitative traits through induced mutagenesis using UV-B radiation to impel the novel characteristics of plant

Green soybean seeds: effect on physiological quality / Sementes de soja esverdeada: efeito na qualidade fisiológica

ABSTRACT: The objective of this research was to assess the manner in which the presence of green soybean seeds affects their physiological quality. In this study, six lots of soybean seeds of cultivar 5958RSF IPRO with 0, 0, 7, 8, 16 and 18% of green seeds were examined. The tests done included the first germination count, germination, electrical conductivity, field emergence, accelerated aging, emergence speed index, Tetrazolium, length, dry mass and seedling growth curve. Results were tested employing the normality test and analysis of variance, and the means were compared by the Tukey test at 5% probability level, employing the Rbio statistical program. Growth data were analyzed by the nonlinear regression analytical method, using the SigmaPlot 12.0 software. The viability and vigor of the greenish seeds were confirmed to reveal higher deterioration, proportional to the percentage of seeds in which the cotyledons had green pigmentation, indicating that the presence of chlorophyll caused the physiological quality of the soybean seeds to decrease.

RESUMO: Neste trabalho o objetivo foi avaliar a influência da presença de sementes esverdeadas de soja na sua qualidade fisiológica. Para tanto, foram utilizados seis lotes de sementes de soja da cultivar 5958RSF IPRO com 0, 0, 7, 8, 16 e 18% de sementes esverdeadas. Os testes realizados foram: primeira contagem de germinação, germinação, condutividade elétrica, emergência em campo, envelhecimento acelerado, índice de velocidade de emergência, tetrazólio, comprimento, massa seca e curva de crescimento de plântulas. Os resultados foram submetidos ao teste de normalidade e análise de variância, seguido de comparações de médias, pelo teste de Tukey ao nível de 5% de probabilidade, com auxílio do programa estatístico Rbio. Os dados de crescimento foram submetidos à análise de regressão não-linear, utilizando o software SigmaPlot 12.0. Para as sementes esverdeadas, constata-se menor viabilidade e vigor devido a maior deterioração, proporcional a porcentagem de sementes com pigmentação verde nos cotilédones, de forma que a presença de clorofila reduz a qualidade fisiológica de sementes de soja.

Effects of different treatments on seed germination and seedling growth of Bupleurum chinense / 中草药

Objective: To study the effects of different pretreatment methods and culture temperatures on Seed Germination and seedling growth of Bupleurum chinense, in order to provide scientific basis for artificial cultivation of B. chinense. Methods: Several physiological indexes such as the weight, pure rate, content of moisture, the rate of water absorption per thousand seeds were measured. Adopting a double-layer filter paper culture method, the pretreated seeds were cultured in the incubator at 20 ℃ in the 40% light. In different culture temperature treatment groups, the seeds were soaked in distilled water 24 h and then cultured in the corresponding temperature incubator. The germination energy, germination percentage, germination index, vigor index of seeds, and the root length and the shoot height of the seedling were recorded. Results: The pure rate of seeds was 91.51%, the weight of one thousand seeds was (2.83 ± 0.03) g and the weight of seed after absorbing water was about 2.24 times more than the weight of naturally dried seed. The content of moisture of seeds was 7.3%. Different hormones had different effects on seeds, among them the effect of 0.6 mg/L 6-BA treatment was the best. Water bath could increase the seedling vigor index, and 40 ℃ of its temperature significantly promoted the seed germination and seedling growth. The germination rate of seeds was the highest under the condition of 15 ℃, but the root length and seedling height were lower. Conclusion: The suitable condition for seed pretreatment and culture temperature of B. chinense established in this research can effectively improve the germination rate and seedling rate, which is of great significance for seed breeding and artificial cultivation of B. chinense.

Seedling growth and survival of five tree species in secondary forests and adjacent pastures in the montane rain forests of Southern Costa Rica / Crecimiento y supervivencia de plántulas de cinco especies de árboles en bosques secundarios y pastizales adyacentes en un bosque lluvioso montano del sur de Costa Rica

Abstract:Successful forest restoration in tropical environments is limited by the paucity of studies on the initial establishment and early survival requirements of seedlings of most native tropical tree species under disturbed conditions. Here, we evaluated the initial growth responses and the regeneration potential of seedlings of five tree species native to Costa Rica (Hasseltia floribunda, Inga densiflora, Persea americana, Tapirira mexicana and Trichilia pittieri). Seedlings were grown in secondary forests and adjacent open pastures under contrasting conditions of light availability. We quantified seedling growth, survival and herbivory from August 2010 to August 2011 on a monthly basis, and measured differences in leaf mass per area (LMA) at the end of the experiment. We found significant variation in growth responses between the understory of secondary forests and pastures. Growth in height was highest in pastures across all species, with I. densiflora, P. americana and T. mexicana showing the most striking differences. In contrast, H. floribunda and T. pittieri did not show differences in diameter growth between environments. Except for T. mexicana, herbivory increased throughout the experiment in all the species. Herbivory increased faster in pastures for H. floribunda and T. pittieri and showed higher rates in the forest understory for I. densiflora and P. americana. Seedling survival showed significant differences for all species across environments. Survival of H. floribunda and I. densiflora was higher in secondary forests, whereas the other species showed higher survival in pastures. LMA showed higher values in the pastures across all species, showing that individuals exposed to high light conditions had great photosynthetic rate and great leaf construction capacity. Due to their rapid growth and high survival, I. densiflora and T. mexicana showed great potential to restore abandoned pastures and secondary forests. Increasing our knowledge on the response of seedlings under disturbed conditions in tropical ecosystems is critical for improving the restoration of altered environments by matching the ecological amplitude of native species with specific environmental conditions. Rev. Biol. Trop. 64 (4): 1565-1583. Epub 2016 December 01.

Resumen:La restauración exitosa del bosque en ambientes tropicales está limitada por la carencia de estudios sobre los requisitos de hábitat, el establecimiento inicial, y la sobrevivencia de las plántulas de la mayoría de las especies de árboles tropicales nativos. En este estudio, evaluamos las respuestas en el crecimiento inicial y el potencial de regeneración de las plántulas de cinco especies de árboles nativos de Costa Rica (Hasseltia floribunda, Inga densiflora, Persea americana, Tapirira mexicana y Trichilia pittieri). Sembramos las plántulas en bosques secundarios y en pastizales abiertos adyacentes con condiciones de luz contrastantes. Cuantificamos el crecimiento, la supervivencia y el daño por herbivoría de las plántulas de forma mensual entre agosto 2010 y agosto 2011, y medimos las diferencias en el la masa foliar por área de la hoja al final del experimento. Existió una variación significativa en el crecimiento de las plántulas expuestas a la sombra en los bosques secundarios y aquellas que crecieron en pastizales. El crecimiento en altura fue mayor en pastizales en todas las especies; I. densiflora, P. americana y T. mexicana mostraron la mayor diferencia entre ambientes. En con- traste, H. floribunda y T. pittieri no mostraron diferencias en el crecimiento del diámetro entre ambientes. Con la excepción de T. mexicana, todas las especies mostraron un aumento en herbivoría durante el estudio. En los pastizales, el incremento de la herbivoría fue más rápido en H. floribunda y T. pittieri, mientras que para I. densiflora y P. americana fue mayor en el bosque. La sobrevivencia de plántulas fue diferente entre ambientes para todas las especies. La sobrevivencia de H. floribunda e I. densiflora fue mayor en el bosque secundario, mientras que en las demás especies hubo mayor sobrevivencia de plántulas en los pastizales. La masa foliar por área fue mayor en las plántulas que crecieron en los pastizales que en bosque secundario para todas las especies, lo que sugiere que los individuos que crecieron en condiciones de alta incidencia de luz tuvieron mayor tasa fotosintética y mayor capacidad de construcción de la hoja. Debido al rápido crecimiento y alta supervivencia I. densiflora y T. mexicana tienen gran potencial para la restauración de bosques secundarios y pastizales abandonados. Generar información sobre la respuesta de plántulas creciendo en bosques secundarios y pastizales en regeneración es crítico para mejorar los procesos de restauración de ambientes alterados. La restauración de estos bosques depende de la correspondencia entre las condiciones específicas de hábitat y la plasticidad ecológica de las especies nativas.

Effects of different endophytic fungi on seedling growth of Dendrobium devonianum / 中国中药杂志

To obtain seedling growth-promoting fungi is a key step in restoration-friendly cultivation of medicinal Dendrobium species, since there are a large number of functionally-unknown endophytic fungi in the roots of Dendrobium plants.In this study, six functionally-unknown endophytic fungal strains were isolated from roots of D.devonianum using single peleton isolation technology, and used in inoculation experiments to test their effectiveness for seedling growth in D.devonianum.After 90 days of inoculation, comparing with the control treatment, FDdS-1, FDdS-2 and FDdS-4 showed strong pathogenic or fatal effects on seedlings; while, FDdS-12, FDdS-9 and FDdS-5 had different effects on seedling growth.FDdS-5 had significant promoting effects on height, fresh and dry weight, stem diameter and root numbers, while FDdS-9 only had significant promoting effect on seedling height, and FDdS-12 had a negative effect on seedling growth.According to the anatomical features of the inoculated roots, FDdS-5 fungi could infect the velamina of seedlings and the existence of symbiosis pelotons in the cortex cells, suggesting that FDdS-5 is a mycorrhiza fungi of D.devonianum.FDdS-5 and FDdS-9 were identified as Sebacina vermifera and Sebacina sp.by molecular technologies.By using FDdS-5 in the restoration-friendly cultivation of D.devonianum, it could effectively promote seedling growth and shorten the seedling growth periods.The results will aid in reintroduction and cultivation of D.devonianum.

ATIVIDADE FITOTÓXICA DE CASCAS DO CAULE E FOLHAS DE Blepharocalyx salicifolius (MYRTACEAE) SOBRE ESPÉCIES INFESTANTES / Actividad fitotóxica de las cortezas del tallo y hojas de Blepharocalyx salicifolius (Myrtaceae) sobre especies invasoras / Phytotoxic Activity of Stem Bark and Leaves of Blepharocalyx salicifolius (Myrtaceae) on Weeds

No presente estudo foi avaliada a fitotoxicidade de extratos e frações de cascas do caule (súber) e folhas maduras de Blepharocalyx salicifolius Kuth O. Berg sobre o crescimento inicial de Echinochloa crus-galli L. P. Beauv. (capim-arroz) e Euphorbia heterophylla L. (amendoim-bravo). Os extratos foram obtidos por meio de extração exaustiva e fracionamento por coeficiente de partição com solventes orgânicos. Posteriormente, os extratos acetato etílicos de cascas e folhas maduras e o extrato hexânico de cascas foram fracionados por cromatografia em coluna com a utilização de solventes em ordem crescente de polaridade. Os extratos e as frações foram testados sobre as espécies infestantes nas concentrações de 0,2, 0,4 e 0,8 mg.mL-1, como controle positivo foi utilizado o herbicida comercial Sanson® nas mesmas concentrações descritas e como controle negativo água destilada com DMSO (5 uL/mL). Os extratos acetato etílicos de cascas e folhas maduras, assim como o extrato hexânico de cascas apresentaram efeitos pronunciados de inibição sobre o crescimento das espécies-alvo. Das oito frações acetato etílicas de folhas, seis inibiram o crescimento das raízes de capim-arroz e quatro inibiram o crescimento das raízes e parte aérea de amendoim-bravo em todas as concentrações testadas. Das seis frações acetato etílicas de cascas, quatro apresentaram fitotoxicidade sobre o crescimento das raízes de capim-arroz em todas as concentrações. Os extratos e frações de cascas e folhas maduras levaram ao surgimento de anomalias nas espécies-alvo. Estes resultados evidenciaram o acentuado efeito fitotóxico dos extratos e frações de cascas e folhas maduras e seu potencial uso como herbicida natural.

RESUMEN En este estudio se evaluó la fitotoxicidad de los extractos y fracciones de las cortezas del tallo (suber) y de las hojas maduras de Blepharocalyx salicifolius Kuth O. Berg sobre el crecimiento inicial de Echinochloa crus- galli L. P. Beauv. (capim-arroz) y Euphorbia heterophylla L. (amendoim-bravo). Estos extractos fueron obtenidos por extracción exhaustiva y fraccionamiento por coeficiente de partición con disolventes orgánicos. Posteriormente los extractos de acetato de etilo de las hojas y de la corteza del tallo (suber) fueron fraccionados por cromatografía de columna con disolventes de polaridad creciente. Tanto los extractos como las fracciones se ensayaron sobre las plantas diana en concentraciones de 0,2, 0,4 y 0,8 mg.mL-1, como control positivo se utilizó el herbicida comercial Sanson® disuelto en las mismas condiciones y como control negativo agua destilada con DMSO (5uL/mL). Los extractos de acetato de etilo de hojas maduras y corteza así como el extracto de hexano de la corteza mostraron los efectos inhibitorios más pronunciados sobre el crecimiento de las especies diana. De las ocho fracciones del extracto de acetato de etilo de hojas, seis inhibieron el crecimiento de las raíces de capim-arroz y cuatro fracciones inhibieron el crecimiento de las raíces y de la parte aérea de amendoin-bravo en todas las concentraciones ensayadas. De las seis fracciones del extracto de acetato de etilo de corteza, cuatro fueron fitotóxicos sobre el crecimiento de la raíz de capim-arroz en todas las concentraciones. Los extractos y fracciones de la corteza y de las hojas maduras provocaron anomalías en las especies diana. Estos resultados demostraron un efecto fitotóxico pronunciado de los extractos y fracciones de corteza y hojas maduras y su potencial uso como herbicidas naturales.

In this study, the phytotoxicity of extracts and fractions of stem bark (suber) and mature leaves of Blepharocalyx salicifolius Kuth O. Berg was evaluated on the initial growth of Echinochloa crus- galli L. P. Beauv. (barnyardgrass) and Euphorbia heterophylla L. (wild poinsettia). The extracts were obtained by exhaustive extraction and fractionation by the partition coefficient with organic solvents. Subsequently, the ethyl acetate extracts of bark and mature leaves and the hexane extract of bark were fractionated by column chromatography with solvents in increasing order of polarity. The extracts and fractions were evaluated on weed species at concentrations of 0,2, 0,4 and 0,8 mg.mL-1, The positive control used was the commercial herbicide Sanson® at the same concentrations described and the negative control used was distilled water with DMSO (5 uL/mL). The ethyl acetate extracts of bark and mature leaves and hexane extract of bark showed the most pronounced inhibitory effects on the growth of the target species. Among the eight ethylic acetate leave's fractions, six inhibited the root growth of barnyardgrass at all concentrations tested and four fractions inhibited the root and shoot growth of wild poinsettia, at all concentrations tested. Of the six ethylic acetate bark's fractions, four showed phytotoxicity on root growth of barnyardgrass at all concentrations. The extracts and fractions of bark and mature leaves have given rise to anomalies in the target species. The results demonstrated a pronounced phytotoxic effect of the extracts and fractions of bark and mature leaves, providing subsidies for their use as natural herbicides.

Evaluation of allelopathic potential of leaf extract of Kielmeyera coriacea on Lactuca sativa L / Avaliação do potencial alelopático de extrato de folhas de Kielmeyera coriácea sobre Lactuca sativa L

Kielmeyera coriacea Mart. (Clusiaceae), popularly known as "pau-santo", is a typical Brazilian cerrado tree known due to its varied secondary metabolites. This study aimed to determine the allelopathic potential of the hydroalcoholic extract of leaves of K. coriacea through bioassays of seed germination, seedling growth and mitotic index of Lactuca sativa L. (lettuce). In addition it was done the tetrazolium assay and a phytochemical screening. The extract concentrations caused alterations in germination parameters, in root growth and in the mitotic index. The phytochemical screening showed the presence of triterpenes, coumarins, steroids, flavonoids and condensed tannins, compounds known to confer allelopathic characteristics upon other species. These data indicate that K. coriacea presents an allelopathic potential because its leaf extracts interfere with germination and growth without any interference of pH and osmotic potential in the results.

Kielmeyera coriacea Mart. (Clusiaceae), conhecida popularmente como "pau-santo", é uma árvore típica do cerrado brasileiro, conhecida pelos seus variados metabólitos secundários. O estudo teve como objetivo determinar o potencial alelopático do extrato hidroalcoólico de folhas de K. coriacea por meio dos bioensaios de germinação, crescimento de plântulas e índice mitótico de Lactuca sativa L. (alface). Além disso, foi feito o teste de tetrazólio e uma triagem fitoquímica. As concentrações de extrato causaram alterações nos parâmetros de germinação, no crescimento radicular e no índice mitótico. A triagem fitoquímica mostrou a presença de triterpenos, cumarinas, esteroides, flavonoides e taninos condensados, compostos conhecidos por conferir características alelopáticas sobre outras espécies. Estes dados indicam que K. coriacea apresenta potencial alelopático pois o extrato de sua folha interfere na germinação e no crescimento da planta alvo, sem qualquer interferência do pH e do potencial osmótico.

Effects of exogenous salicylic acid on seed germination and seedling growth of Pogostemon cablin under salt stress / 中草药

Objective: To study the effects of exogenous salicylic acid (SA) on the seed germination and seedling growth of Pogostemon cablin under salt stress and the optimal concentration of SA for alleviating the salt stress. Methods: Under salt stress simulated by 50 mmol/L NaCl solution, P. cablin was used to investigate the effects of exogenous SA on the seed germination and seedling growth with paper media. The germination energy (GE), germination rate (GR), germination index (GI), vigor index (VI), seedling length (SL), root length (RL), seedling fresh weight (SFW), seedling dry weight (SDW), and contents of soluble protein (SP) and chlorophyll in the leaves were determined, and the relative salt-damage rate of these indexes was analyzed. Results: The seed germination and seedling growth of P. cablin were significantly inhibited under 50 mmol/L NaCl stress. Compared with NaCl stress, the seed germination and seedling growth were improved when SA were 0.10 and 0.25 mmol/L, while reduced when SA was 0.50 mmol/L. GE, GR, GI, VI, SL, RL, SFW, SDW, and contents of SP and chlorophyll were significantly improved by 46.02%, 27.45%, 30.16%, 92.63%, 39.80%, 47.94%, 26.48%, 18.85%, 15.94%, and 14.70% with 0.25 mmol/L SA, as well as MDA content was significantly reduced by 18.35%. Conclusion: SA could improve the ability of the seed germination and seedling growth of P. cablin to adapt the environment and alleviate the inhibitory effects of salt stress. Among all the treatments, the optimal concentration of SA is 0.25 mmol/L.

Germinação de sementes de Aspidosperma subincanumMart. ex A. DC em diferentes temperaturas / Germination of Aspidosperma subincanum Mart. ex A. DC seeds at different temperatures

RESUMO : Aspidosperma subincanum é uma espécie arbórea utilizada em projetos de recuperação de áreas degradadas e como planta medicinal. Levando-se em consideração a importância da espécie, o presente trabalho teve como objetivo definir a temperatura ideal para a germinação de suas sementes. O material vegetal foi coletado na região do Pantanal de Miranda, Mato Grosso do Sul. As sementes foram colocadas em caixas plásticas transparentes em câmara de germinação e submetidas às temperaturas constantes de 20, 25, 30 e 35°C e alternadas de 20-30 e 25-35°C. O delineamento experimental foi inteiramente casualizado, com quatro repetições por tratamento, sendo as médias comparadas pelo teste de Tukey a 5%. A temperatura ideal para a germinação de Aspidosperma subincanum foi a 25°C, com o maior índice de velocidade de germinação, 18,8. Temperaturas mais elevadas (30 e 35°C) causaram a morte dos embriões

ABSTRACT Germination of Aspidosperma subincanum Mart. ex A. DC seeds at different temperatures. The Aspidosperma subincanumem is a tree species used in the recovery of degraded areas projects and as a medicinal plant. Taking into account the importance of the species, the current study aimed to determine which would be the ideal temperature for the germination of their seeds. The plant material was collected in the Pantanal of Miranda, Mato Grosso do Sul. The seeds were placed in transparent boxes in germination chambers and submitted to constant temperatures of, 20, 25, 30 and 35°C and alternated at 20-30 and 25- 35°C, with four replicates per treatment. The statistical design was a completely randomized one. The averages were compared by Tukey test at 5%. The ideal temperature for germination of Aspidosperma subincanum was 25°C. The high temperatures (30 and 35°C) have caused the death of embryos

Allelopathic effect of Tridax procumben on four kinds of crops / 中草药

Objective: To study the allelopathic effect of water extract from Tridax procumbens (WETP) on the seed germination and seedling growth of four kinds of crops. Methods: By water extraction, the stems, leaves, and seeds of T. procumbens were extracted, respectively. The seeds and seedlings of the four kinds of crops were treated with WETP, using distilled water as a control, and the differences between the seeds at four kinds of concentration were analyzed. Results: The synthetic action of WETP on Vigna radiata is promoting. With the increasing concentration, the promoting is diminished. But the effects of WETP on Raphanus sativus, Brassica campestris, and Lactuca sativa were promoting at low concentration and inhibition at high concentration. The inhibitory sequences of water extracts of different parts were seeds > leaves > stems, and for the seeds, L. sativa > R. sativus > B. campestris > V. radiata. The inhibition on L. sativa was the most significant. Conclusion: T. procumbens has the allelopathic effect on native plants. Therefore, T. procumbens could be used as herbicide and cover plant for competition to inhibit other weeds. It has a development and application value.

Effects of silicon addition on seed germination and seedling growth of Glvarrhiza uralensis under salt stress / 中草药

Objective: In this study, a water culture experiment was conducted to investigate the effects of silicon addition on the seed germination and seedling growth of Glvarrhiza uralensis under salt stress. Methods: Various components of the experiment were three salt treatments (50, 100, and 150 mmol/L NaCl) and six Si levels (0, 1, 2, 4, 6, and 8 mmol/L) in distilled water. Potassium silicate (K2SO4) was used as a source of Si. Results: The result showed that silicon addition had the significant effect on the seed germination and seedling growth, and this effect was dependent on the salt stress level and silicon addition concentration. Under 50 and 100 mmol/L NaCl stress condition, lower concentration silicon addition had no significant effect on the germination rate, germination index, seedling emergence rate, and radical length, while had the significantly promoted effect on plant height, and root and shoot dry weight of G. uralensis. However, higher concentration silicon addition had the significantly inhibited effect on the seed germination and seedling growth. Under 150 mmol/L NaCl stress condition, silicon addition at lower concentration significantly promoted the seed germination and seedling growth of G. uralensis, including the germination rate, seedling emergence, germination index, seedling vigor, radical and embryo length, and root and shoot dry weight. However, silicon addition at higher concentration significantly inhibited the seedling growth of G. uralensis, while had no significant effect on the seed germination. Conclusion: Silicon is directly involved in the physiological process of the seed germination and seedling growth of G. uralensis under salt stress condition, and this involved extent is dependent on the salt stress level and silicon addition concentration.

Effects of different soaking treatments on seed germination and seedling growth of Platycodon grandiflorum / 中草药

Objective: To investigate the effects of different soaking treatments by KNO3, KMnO4, H2O2, GA3, and distilled water for different times on seed germination and seedling growth of Platycodon grandiflorum. Methods: Adopting a double-layer filter paper culture method, the seeds were cultured in the 12 h illumination light incubator at 25 °C, and the germination energy, germination percentage, germination index of the seeds, and the root length and the shoot height of the seedling were recorded. Then the data were analyzed. Results: The best soaking treatment to break seed dormancy, promote the seed germination, and improve the seedling growth of P. grandiflorum was with 0.150 g/L GA3 for 24 h. In addition, another effective soaking treatment is using 0.005 g/mL KNO3 for 12 h. Conclusion: The appropriate soaking reagent and time for the seed germination of P. grandiflorum are obtained, which could provide the guidance for seedling and artificial cultivating P. grandiflorum.

Potential of antioxidant enzymes in depicting drought tolerance of wheat (Triticum aestivum L.).

In an effort to determine the biochemical markers for identifying genotypes before sowing for drought tolerance, changes in activities of antioxidant enzymes were determined in the seedlings of five drought-tolerant and five drought-sensitive wheat (Triticum aestivum L.) genotypes, each with different genetic background growing under normal and water deficit conditions induced by 6% mannitol. In comparison with non-stressed seedlings, the catalase (CAT) activity was upregulated by more than 50% in the roots of water-stressed seedlings in drought-tolerant genotypes. Water deficit stress also led to the upregulation of ascorbate peroxidase (APX) in the endosperms and glutathione reductase (GR), CAT and peroxidase (POD) in the shoots of stressed seedlings in drought-tolerant genotypes. Superoxide dismutase (SOD) activity was very low in roots and shoots and showed non-significant increase under water-stress in tolerant genotypes. Out of five specified enzyme activities (CAT in roots and shoots, APX in endosperms, GR and POD in shoots), if any three are upregulated in the specified tissues under water deficit conditions, the genotype is likely to be drought-tolerant. Wheat seedlings with low GR and APX activities and high POD activity in shoots with a low ratio of GR activity of shoot to root of non-stressed seedlings are likely to perform better under rainfed conditions. The observed data showed that status of antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of a wheat genotype.

Enhancement in the germination, growth and yield of Okra (Abelmoschus esculentus) using pre-sowing magnetic treatment of seeds.

The effect of pre-sowing magnetic treatments was investigated on germination, growth and yield of okra (Abelmoschus esculentus cv. Sapz pari). The dry okra seeds were exposed to sinusoidal magnetic field induced by an electromagnet. The average magnetic field exposure was 99 mT for 3 and 11 min and seeds with no magnetic field treatment were considered as control. Both treated and non-treated seeds were sown in experimental plots (120 m2) under similar conditions. Samples were collected at regular intervals for statistical analysis. A significant increase (P<0.05) was observed in germination percentage, number of flowers per plant, leaf area (cm2), plant height (cm) at maturity, number of fruits per plant, pod mass per plant and number of seeds per plant. The 99 mT for 11 min exposure showed better results as compared to control.

Growth, photosynthetic activity and oxidative stress in wheat (Triticum aestivum) after exposure of lead to soil.

The present study was conducted to assess quantitative information about lead (Pb) contamination in soil on the growth and physiology of wheat. Solutions with three different concentrations of Pb as [Pb(NO3)2 at 500, 1000 and 2500 >M] were incorporated into the soil to achieve Pb-stressed conditions in comparison to unstressed, water treated, control variant. Wheat growth measured in terms of root length, shoot length and dry weight exhibited a significant decline with increasing Pb concentrations in the soil. Root and shoot length and seedling weight declined in the range of ~23–51, ~17–44, and ~21–44% in response to 500 to 2500 >M Pb. In addition, there was a significant reduction in the levels of photosynthetic pigments-chlorophyll a (16-66%) and b (10-24%) and total chlorophyll content (by 14-39%) in plants growing in Pb-contaminated soil. It indicated a negative effect on photosynthetic activity in wheat and was confirmed by reduced photochemical efficiency of PSII (Fv/Fm) in the range of ~ 3-37% in response to 500 to 2500 >M Pb. The reduction in wheat growth in Pb-contaminated soil was accompanied by induction of oxidative stress as indicated by enhanced lipid peroxidation in terms of malondialdehyde (MDA) content (by 18-40%) and hydrogen peroxide (H2O2) content (by 34-123%) and alterations in the activity of enzymes, superoxide dismutases (SOD) and guaiacol peroxidases (GPX) in wheat roots. The study concludes that Pb in soil inhibits growth and phototsynthetic activity in wheat through induction of oxidative stress.

Phytotoxic effect of 2-benzoxazolinone (BOA) against some vegetable crops.

Benzoxazolin-2(3H)-one (BOA) is a well known allelochemical that is being explored for its herbicidal activity. However, not much is known about its effect on crop plants. The present study investigated the effect of BOA on germination and early growth of four vegetable crops viz. Pisum sativum L., Raphanus sativus L., Brassica oleracea L. var. botrytis and Brassica oleracea L. var. capitata. At 1000 <M, germination of P. sativum, R. sativus and B. oleracea var. botrytis was reduced by more than 50%, whereas that of B. oleracea var. capitata was completely suppressed. Further, BOA reduced the root and shoot length of the test plants by ~ 40-82% and ~55-85%, respectively. In general, the effect was more pronounced on the root (~82% in B. oleracea var. botrytis) than on the shoot growth (~73% B. oleracea var. botrytis). 2- Benzoxazolinone significantly enhanced the contents of proteins (by 6-28%) and carbohydrates (by 61- 189%) in B. oleracea var. capitata and decreased the activities of related enzymes like proteases (by 13- 36%), a-amylases (19-60%) and b-amylase (25-70%). The observed decline in the activities of hydrolytic enzymes amylases suggest that BOA interferes with the vital metabolic processes in the germinating seedlings leading to growth reduction. The study reveals that BOA interferes with the germination and early seedling growth of vegetable crops and induces biochemical alterations.

Seed germination and seedling growth of two Pseudobombax species (Malvaceae) with contrasting habitats from Brazilian Cerrado

Pseudobombax tomentosum and P. longiflorum are common trees in the Cerrado region, but the former species is more common in forest edges while the later is present in open cerrado areas. This work aimed to investigate differences in seed germination and seedling growth in these species, from seed collected from Cerrado areas in Central Brazil. For this, a seed germination experiment was designed and included four replicates with 25 seeds per species; seeds were randomly distributed in the germination chamber. To evaluate initial seedling growth, seedlings height was measured up to 67 days after seedling emergence; besides, some of these seedlings were grown for biomass evaluation during nine months. Results showed that seeds of the two species had the same germinability (near 100%) and mean germination time (ca. 12 days). However, P. longiflorum showed a more spread seed germination through time, with higher values of coefficient of variation in germination time and uncertainty index; and lower values of synchronization than P. tomentosum. The two species showed basically the same growth pattern, but lower values for height of apical meristem, diameter of underground structures (mostly roots), dry mass of shoots, underground structure and total mass of seedlings in P. tomentosum were obtained, compared to P. longiflorum. Both species allocated more dry mass to underground structures in detriment of shoot. This probably allows resprouting behavior which prevents hydric stress and detrimental fire action typical of the open Cerrado areas. Rev. Biol. Trop. 59 (4): 1915-1925. Epub 2011 December 01.

Pseudobombax tomentosum y P. longiflorum son árboles comunes en la región del Cerrado, pero la primera especie es más común en los bordes del bosque mientras que el segundo está presente en áreas abiertas del cerrado. Este trabajo tuvo como objetivo investigar las diferencias en la germinación de las semillas y el crecimiento de ambas especies. Los individuos fueron recolectados en áreas del Cerrado, la región de savanas neotropicales en el centro de Brasil. Fueron utilizados para cada especie cuatro repeticiones con 25 semillas cada una para el experimento de germinación, distribuidas al azar en la cámara de germinación a 25ºC. Las plántulas fueron evaluadas en cuanto al crecimiento inicial hasta 67 días después de la emergencia de la plántula. Algunas plantas se mantuvieron para la evaluación de la biomasa durante nueve meses, y luego se mideron para evaluar diferencias en el crecimiento y distribución de masas entre especies. Ambas presentaron la misma capacidad germinativa (cerca de 100%) y tiempo medio de germinación (alrededor de 12 días). Sin embargo, P. longiflorum presentó una germinación más dispersa en el tiempo, con valores más altos de coeficiente de variación de tiempo de germinación y el índice de incertidumbre, y valores más bajos de la sincronización que P. tomentosum. Las dos especies demostraron básicamente el mismo patrón de crecimiento, pero P. tomentosum presentó valores más pequeños en la altura del meristemo apical, diámetro de las estructuras subterráneas (sobre todo las raíces), masa seca de la estructura aérea, estructura subterránea y plántulas en comparación con P. longiflorum. Ambas especies asimilaron más masa seca en las estructuras subterráneas en detrimento de las aéreas. Esto probablemente permite una conducta de rebrote que evita el estrés hídrico y la acción perjudicial de incendios típicos de las zonas del cerrado abierto.

Zinc and copper induced changes in physiological characteristics of Vigna mungo (L.).

The effect of deleterious concentration of zinc and copper provided either individually or in combination in the nutrient media was investigated in order to assess the effect of metal interaction in Vigna mungo (L.). Both metals showed negative effect and led to a marked decrease in seed germination (20%), seedling growth (91.7%) and nitrate reductase activity (85.7%) with the increase in metal concentrations. The present study also emphasizes on the response of catalase and peroxidase enzyme under zinc and copper stress. Both antioxidant enzymes exhibited an increasing trend under different treatment conditions but it was reverse at highly toxic metal concentration. The results showed active involvement of peroxidase enzyme in regulating oxidative stress rather than catalase enzyme, as the specific activity of peroxidase enzyme got increased by 8.94% under the combined metals stress whereas catalase activity got declined by 60.97% in comparison to control due to excessive stress. The combined effect of copper and zinc metal was more pronounced in comparison to their individual effects.