Resumo: O priming de sementes com ácido salicílico (AS) tem sido descrito como um método com potencial para melhorar a germinação sob condições desfavoráveis. Objetivou-se avaliar a capacidade do condicionamento com AS em atenuar o impacto da restrição hídrica durante a germinação e crescimento inicial de plântulas de tomate. As sementes foram submetidas a distintas concentrações de AS (0, 25 e 50 µM) e semeadas em substratos a diferentes percentagens da capacidade de restrição de água (20, 30, 40 e 100%). As variáveis avaliadas foram: germinação, primeira contagem de germinação, índice de velocidade de germinação, comprimento e massa seca da parte aérea/raiz, atividades de superóxido dismutase, ascorbato peroxidase e catalase, conteúdos de peróxido de hidrogênio e malondialdeído. A restrição hídrica diminuiu significativamente as variáveis relacionadas à germinação e o desempenho das plântulas. Apesar de incrementar a velocidade de germinação e o desenvolvimento das plântulas quando aplicado em condições bem irrigadas, o priming com AS impactou negativamente tais características sob condições de déficit hídrico. Isto através de aumentos na atividade da superóxido dismutase e acumulação de H2O2. Assim, conclui-se que o condicionamento de sementes com AS não aprimora a germinação e crescimento inicial de plântulas de tomate sob condições de déficit hídrico.

Abstract: Seed priming with salicylic acid (SA) has been described as a method with potential to improve seed germination under unfavorable conditions. The present study aimed to evaluate the ability of seed priming with SA to attenuate the impact of water restriction during germination and early seedling growth of tomato. Seeds were subjected to different concentrations of SA (0, 25 and 50 µM) and sowed on substrates at different percentages of the water holding capacity (20, 30, 40 and 100%). The following variables were evaluated: germination, first count of germination, germination speed index, shoots/root length and dry mass, superoxide dismutase, ascorbate peroxidase and catalase activities, contents of hydrogen peroxide and of malondialdehyde. Water restriction significantly decreased the variables related to germination and seedling performance. Despite increasing germination speed and seedling development when combined with well-irrigated conditions, priming with SA negatively impacted those characteristics under water deficit conditions. That was through increases in superoxide dismutase activity and H2O2 accumulation. Thus, it was concluded that seed priming with SA does not improve tomato seed germination and early seedling growth under water deficit.

RESUMO: O presente estudo objetivou avaliar as respostas fisiológicas de dois genótipos de grama forquilha (Paspalum notatum Flügge) sob restrição hídrica induzida por polietileno glicol (PEG6000) durante a germinação de sementes. Sementes da cv. Pensacola (diplóide) e do ecótipo Bagual (tetraplóide) foram colocadas em papel umedecido com soluções osmóticas nos potenciais de 0,0; -0,1; -0,2 e -0,3 MPa. Composto de duas subamostras de 100 sementes e quatro unidades experimentais por tratamento, o teste de germinação foi conduzido em câmara de germinação sob temperatura alternada de 30-20 ºC, com presença de luz durante a maior temperatura. Foram avaliados a porcentagem final e o índice de velocidade de germinação das sementes, assim como o crescimento inicial, a atividade e a expressão de enzimas antioxidantes das plântulas. A restrição hídrica induzida por PEG6000 reduziu o percentual de germinação em Pensacola (de 74 para 59%) e Bagual (34 para 10%). Este último, na avaliação de plântulas, apresentou massa seca superior em relação à cv. Pensacola (1.7 vezes superior em raiz e 1.6 vezes superior em parte aérea). Em resposta à restrição hídrica moderada, os genótipos apresentaram aumentos tanto do crescimento radicular (1.7 vezes superior em -0.1 em comparação com 0.0 MPa), quanto da expressão e da atividade enzimática (superóxido dismutase e catalase).

ABSTRACT: The objective of the following research was to investigate the physiological responses of two bahiagrass genotypes (Paspalum notatum Flügge) submitted to water restriction, induced by polyethylene glycol (PEG6000), during seed germination. Seeds of cv. Pensacola (diploid) and Bagual ecotype (tetraploid) were placed on paper moistened with osmotic solutions at potentials of 0.0; -0.1; -0.2 and -0.3 MPa. Composed of two subsamples of 100 seeds and four experimental units per treatment, the germination test was conducted in a germination chamber under alternating temperatures of 30 °C (8 hours) and 20 °C (16 hours), with presence of light during the higher temperature. Final germination percentage and germination speed index of the seeds, as well as early growth, activity and expression of antioxidant enzymes of seedlings were evaluated. The water restriction induced by PEG6000 reduced the percentage of germination in Pensacola (from 74% to 59%) and Bagual (34% to 10%). For the latter, the evaluation of seedlings showed higher dry mass in relation to cv. Pensacola (1.7 times higher in root and 1.6 times in shoot). In response to moderate water restriction, the genotypes showed increases in root growth (1.7 times higher in -0.1 compared to 0.0 MPa), both in expression and enzymatic activity (superoxide dismutase and catalase).

ABSTRACT: In this work, we compared nitrate-supplied plants (non-nodulated) with non-nitrate-supplied plants (nodulated) under oxygen privation of root system (hypoxia) and re-oxygenation (post-hypoxia; recovery) in order to verify whether N sources affect the antioxidant system during oxidative stress caused by hypoxia and post-hypoxia conditions. Antioxidant enzymatic activities, ascorbate redox state, and reactive oxygen species (ROS) levels were analyzed in roots and leaves of two soybean genotypes, Fundacep 53 RR and BRS Macota at reproductive stage R2, during hypoxia and post-hypoxia in an experiment carried out in a hydroponic system. The antioxidant system was strongly induced in roots of nitrate-supplied plants of both genotypes, with high activity of superoxide dismutase, ascorbate peroxidase, catalase, glutathione reductase and guayacol peroxidase. It also increased reduced ascorbate and ascorbate redox state and decreased ROS production under hypoxia and recovery, while in leaves of nodulated and non-nodulated plants, a slight increase on antioxidant system was observed. Nitrate may benefit soybean plants under hypoxic conditions and subsequent re-oxygenation by inducing the antioxidant system mainly in roots to cope with ROS production and reduce oxidative damage.

ABSTRACT Ultraviolet B radiation has been described as a potential elicitor agent of the synthesis of secondary metabolites in plants. Thus, the present study aimed to investigate the production of betalains and total flavonoids, as well as the antioxidant activity, of Alternanthera sessilis, A. brasiliana, A. tenella and A. philoxeroides exposed to different periods of UV-B radiation (280-315 nm). Plants of these four species were exposed to UV-B radiation for 0, 2, 4, 6, and 8 hours, which amounts to 0, 10, 20, 30, and 40 J cm−2 of radiation, respectively. Significant increases in betacyanin and betaxanthin levels were observed in A. sessilis and A. brasiliana during the period of UV-B exposure, while no differences were observed for the others species. The highest estimated flavonoid levels were for A. sessilis exposed to UV-B radiation for 8 h, followed by a 24-h recovery period. In conclusion, the action of UV-B radiation as an inducer of defence responses in plants is influenced by increasing exposure periods followed by a recovery period. Both increase the levels of these composts, yet this increase is different among the four Alternanthera species, having a greater influence on the species A. sessilis and A. brasiliana.

RESUMO O objetivo deste estudo foi estabelecer um protocolo para indução de calos e produção de betacianinas em plantas de Alternanthera brasiliana. Para indução da calogênese foram utilizados explantes de A. brasiliana e cinco combinações de citocinina e auxina. Posteriormente os calos foram transferidos para Meio de Indução de Betacianinas (MIB), formado por meio MS, com 0,5 mg L-1 de tidiazuron (TDZ) e 1 mg L-1 de ácido naftalenoacético (ANA), onde permaneceram na luz por 45 dias. Avaliou-se oaspecto e a intensidade de pigmentos e quantificação de betacianinas totais em Cromatografia Líquida de Alta Eficiência (CLAE). Os segmentos internodais combinados com o meio que contém equilíbrio na concentração de auxinas e citocininas foi mais eficiente para obtenção de calogênese e maior produção de betacianinas. A presença de amarantina, em calos de A. brasiliana, justifica seu uso medicinal e contribui para futuros estudos para produção em larga escala desta molécula.

ABSTRACT The objective of this study was to establish a protocol for callus induction and betacyanin production in plants of Alternanthera brasiliana. Explants of A. brasiliana and five combinations of cytokinin and auxin were used for callus induction. Calli were transferred to a Betacyanin Induction Medium (MIB), composed of MS, with 0.5 mg L-1 of thidiazuron (TDZ) and 1 mg L-1 of naphthaleneacetic acid (NAA), and kept in the light for 45 days. The aspect and intensity of pigments were assessed and total betacyanins were quantified in high performance liquid chromatography (HPLC). The combination of internodal segments and a medium containing equilibrium concentrations of auxins and cytokinins was the most efficient metod to induce calli and increased production of betacyanins. The presence of amaranthine in calli of A. brasiliana justifies its medical use and the consequent need for future studies for the large-scale production of this molecule.

Waterlogging blocks the oxygen supply to the root system which inhibits respiration, and greatly reduces the energy status of cells that affect important metabolic processes. This study evaluated fermentative metabolism and carbohydrate contents in the root system of two soybean (Glycine max L. Merril) genotypes under hypoxic and post-hypoxic conditions. Nodulated plants (genotypes Fundacep 53 RR and BRS Macota) were grown in vermiculite and transferred to a hydroponic system at the reproductive stage. The root system was submitted to hypoxia by flowing N2 (nitrogen) gas in a solution for 24 and 72 h. For recovery, plants returned to normoxia condition by transfer to vermiculite for 24 and 72 h. Fermentative enzyme activity, levels of anaerobic metabolites and carbohydrate content were all quantified in roots and nodules. The activity of alcohol dehydrogenase, pyruvate decarboxylase and lactate dehydrogenase enzymes, as well as the content of ethanol and lactate, increased with hypoxia in roots and nodules, and subsequently returned to pre-hypoxic levels in the recovery phase in both genotypes. Pyruvate content increased in nodules and decreased in roots. Sugar and sucrose levels increased in roots and decreased in nodules under hypoxia in both genotypes. Fundacep RR 53 was more responsive to the metabolic effects caused by hypoxia and post-hypoxia than BRS Macota, and it is likely that these characteristics contribute positively to improving adaptation to oxygen deficiency.

Este trabalho investiga o efeito do ácido salicílico (um elicitor abiótico) sobre a atividade antioxidante e produção de betacianinas em folhas de Alternanthera tenella cultivada in vitro. As plantas foram cultivadas em meio MS líquido e vermiculita como substrato. Após 35 dias, o ácido salicílico foi adicionado ao meio. Conteúdo de betacianinas, fenóis totais e flavonoides e a capacidade antioxidante não-enzimática foi determinada em folhas de A. tenella após 0, 12, 36 e 48h de tratamento. Após 36h, a concentração de betacianinas e fenóis totais aumentaram. Em contrapartida, o aumento no tempo de exposição causou uma ligeira diminuição nos teores de flavonoides totais e inibição da atividade do radical livre DPPH. Como resultado, a atividade antioxidante de folhas de A. tenella é promovida pelo ácido salicílico e pode ser atribuída ao aumento do conteúdo de betacianina, os quais são compostos com ação antioxidante reconhecida.

This research investigates effects of salicylic acid (an abiotic elicitor) on the antioxidant activity and betacyan production from leaves of Alternanthera tenella cultured in vitro was evaluated. Plants were grown in a liquid MS medium and vermiculite substrate. After 35 days salicylic acid was added to the medium. Content of betacyanins, total phenols and flavonoids and non-enzymatic antioxidant capacity were determined in leaves of A. tenella after 0, 12, 36 and 48h of treatment. After 36h, concentration of betacyanins and total phenols increased. On the other hand, the increase of the treatment time caused a slight decrease in total flavonoids and reduced the DPPH free radical activity. As result the antioxidant activity of the leaves of A. tenella is promoted by salicylic acid and can be attributed to the increase in betacyanin content, which are compounds with recognized antioxidant action.

O objetivo neste trabalho foi analisar o efeito de diferentes temperaturas na qualidade fisiológica e relacionar com a atividade antioxidante de três lotes de sementes de milho, as quais foram expostas por 24h às temperaturas de 15, 25, 35 e 40°C e, após, avaliadas quanto à porcentagem, índice de velocidade e primeira contagem de germinação, como também crescimento inicial e atividade de enzimas antioxidantes nas plântulas. O delineamento experimental foi inteiramente casualizado, com quatro repetições, com posterior análise de regressão polinomial. Os resultados evidenciaram que as sementes dos três lotes de milho, expostas às temperaturas de 15 e 40°C, foram de melhor qualidade fisiológica (vigor), o que explica a baixa atividade das enzimas do sistema de defesa antioxidante nessas mesmas temperaturas. O sistema de defesa antioxidante tem relação com a qualidade fisiológica de sementes de milho expostas ao estresse térmico.

The aim of this research was to analyze the effect of different temperatures on physiological quality and relate the responses with the antioxidant activity of three lots of corn seeds. The seeds from three lots were exposed for 24h at temperatures of 15, 25, 35 and 40°C and then evaluated for percentage, speed index and first germination count, as well as early growth and activity of antioxidant enzymes in the seedlings. The experimental design was completely randomized with four replications, with subsequent polynomial regression analysis. The results showed that the seeds from the three lots of corn exposed to temperatures of 15 and 40°C, were of better high physiological quality (vigor), which explains the low activity of enzymes of the antioxidant defense system in these same temperatures. The antioxidant defense system is related to the physiological quality of corn seeds exposed to thermal stress.

O objetivo deste trabalho foi avaliar a atividade de enzimas fermentativas em raízes e nódulos de soja (Glycine max) sob condições de hipóxia e pós-hipóxia. Os genótipos Fundacep 53 RR e BRS Macota foram cultivados em vasos de 3L contendo vermiculita como substrato em associação com Bradyrhizobium elkanii em casa de vegetação. No estádio R2, o sistema radicular das plantas foi submetido à hipóxia pelo encaixe de um segundo vaso sem perfurações e inundado com solução nutritiva diluída a 1/3 da concentração original, por 8 dias. Posteriormente, foram retirados os vasos sem perfurações para avaliação da recuperação. O material vegetal foi coletado no 2º, 4º, 6º e 8º dias após a inundação ou recuperação, juntamente com os controles para a dosagem da atividade das enzimas álcool desidrogenase (ADH), piruvato descarboxilase (PDC) e lactato desidrogenase (LDH) em raízes e nódulos. Os dados foram submetidos à ANOVA e comparados pelo teste de Tukey a 5% de probabilidade. As atividades da ADH, PDC e LDH foram fortemente estimuladas com a inundação, especialmente em nódulos, e diminuíram com a recuperação, em ambos os genótipos. Fundacep 53 RR respondeu de forma mais efetiva aos efeitos dos tratamentos.

This study aimed to evaluate the activity of fermentative enzymes in soybean (Glycine max) roots and nodules under hypoxia and post-hypoxia conditions. The soybean genotypes Fundacep 53 RR and BRS Macota associated with Bradyrhizobium elkanii were grown in 3L pots containing vermiculite as substrate under greenhouse conditions. Root system of plants at the R2 stage was subjected to hypoxia by blocking drainage of the pot, by fitting a second one without holes and flooded with nutrient solution diluted one-third of the original. The flooding of the plants was carried out for eight days and after, the pot without drilling was removed for recovery assessment. Non-waterlogged plants were kept as control. Activities of the fermentation enzymes alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC) and lactate dehydrogenase (LDH) were quantified in roots and nodules collected at 2, 4, 6 and 8 days after flooding or recovery. Data were analyzed by ANOVA and compared by the Tukey test (P ≤ 0,05). Activities of ADH, PDC and LDH were hardly stimulated during flooding, especially in nodules, in both genotypes and decreased with recovery. Fundacep 53 RR responded more effectively to treatment effects.

Diversas espécies apresentam limitações no desenvolvimento em solos salinos, entretanto, em situações de estresse, o ácido salicílico (AS) pode apresentar função antioxidante. Portanto, objetivou-se analisar modificações fisiológicas em sementes e plântulas de milho tratadas com AS e germinadas em cloreto de sódio, além das respostas do sistema antioxidante em plântulas. As sementes foram embebidas durante 60 minutos em soluções de AS (zero e 1 mM) e colocadas para germinar nas concentrações de NaCl (zero; 30; 90 e 180 mM), sendo avaliadas quanto a germinação, índice de velocidade de germinação, crescimento inicial e atividade de enzimas antioxidantes das plântulas. Para a condutividade elétrica, as sementes foram embebidas em mistura das soluções de NaCl e AS. O AS minimizou os danos causados pela salinização na germinação, que foi prejudicada a partir de 90 mM de NaCl, na ausência de AS. O crescimento inicial foi prejudicado com o aumento das concentrações salinas, enquanto a condutividade elétrica apresentou menor lixiviação de solutos na presença do AS. Houve aumento na atividade das enzimas antioxidantes até 30 mM de NaCl com posterior redução. O AS mantêm a germinação das sementes de milho acima de 90 mM de NaCl, porém, de maneira geral, não é eficiente para garantir o vigor das plântulas.

Several plant species have development limitations on saline soils; however under water stress situations salicylic acid (SA) may have defense function by acting as antioxidant. Thereby, this study was aimed at analyzing physiological changes occurring in maize seeds treated with SA and germinated on sodium chloride moistened substrate; as well as assessing the effect of antioxidant enzymes produced by the seedlings. To this, seeds were soaked into zero and 1 mM SA solutions, for 60 min., and germinated on different NaCl concentrations (0, 30, 90, and 180 mM), and afterwards evaluated for germination, germination speed index, initial growth, and effect of antioxidant enzymes on seedlings. For electrical conductivity test, the seeds were previously soaked in NaCl solutions with and without SA. The SA application has minimized damages induced by salt stress to maize seed germination by favoring their germination percent; however without SA was not able on maintaining seed viability over 90 mM. Seedling initial growth was impaired by increasing NaCl concentrations in substrate; and electric conductivity has shown low values for release of solutes in the presence of SA. Activity of antioxidant enzymes has increased until 30 mM NaCl concentration; however above such concentration activity of these enzymes was reduced. The SA maintains germination of corn seeds above 90 mM NaCl; however, generally it is not efficient to ensure vigor of seedlings.

O objetivo deste trabalho foi analisar o efeito de diferentes temperaturas na atividade respiratória, enzimática e em processos relacionados à qualidade fisiológica de sementes de arroz, bem como utilizar a relação entre esses parâmetros como forma de caracterizar o início do processo de deterioração de sementes. As sementes foram expostas por 24 h às temperaturas de 15; 25; 30 e 35 ºC, e conduzidas aos testes de germinação, primeira contagem de germinação, índice de velocidade de germinação, comprimento e massa seca da parte aérea e raiz, condutividade elétrica, atividade respiratória e enzimática. O delineamento experimental foi inteiramente casualizado, com quatro repetições, sendo as médias comparadas pelo teste de Tukey (p < 0,05) com posterior análise de regressão polinomial. As sementes de arroz apresentaram diminuição na germinação e no vigor a partir de temperaturas superiores a 25 ºC. A atividade respiratória aumentou com o aumento de temperatura, o mesmo ocorreu com a atividade das enzimas aos cinco dias após a semeadura (variando de 14,55 a 59,86 µmol de NAD+g-1 MF min-1 para a malato desidrogenase e de 0,25 a 0,57 µmol de NADPH g-1 MF min-1 para a glicose-6-fosfato desidrogenase). Portanto, pode-se concluir que os testes bioquímicos avaliados podem ser utilizados para identificar o início do processo deteriorativo das sementes de arroz e que temperaturas superiores a 25 ºC depreciam a qualidade destas sementes.

The purpose of this research was to analyze the effect of different temperatures on the respiratory activity, enzymatic and in process related to the physiological quality of rice seeds, and use the relationship between these parameters to characterize the beginning of the deterioration process of seeds. The seeds were exposed during 24 h and conducted tests for germination, first count germination, index the germination speed, length and dry weight of shoot and roots, electrical conductivity, respiratory activity and activity of the enzymes. The experiment was completely randomized with four replicates and the averages compared by Tukey test (p < 0.05) with subsequent analysis of regression. Rice seeds showed that the germination and vigor were reduced above 25 ºC temperatures. Respiratory activity increased with increasing temperature, the same occurred with study enzymes activity in at five days after sowing (ranging from 14.55 at 59.86 µmol of NAD+ g-1 MF min-1 for at malate dehydrogenase and 0.25 at 0.57 µmol of at NADPH g-1 MF min-1 for glucose-6-phosphate dehydrogenase). Therefore, it can be concluded that the evaluated biochemical tests can be used to identify the beginning of the deteriorating process of rice seeds and that temperatures above 25 ºC can depreciate the quality of these seeds.

Este trabalho objetivou avaliar os efeitos alelopáticos de folhas de pariparoba sobre a germinação e o crescimento inicial do rabanete (Raphanus sativus L.). Foram utilizados extratos de folhas maduras frescas nas concentrações 2, 4 e 8% (p/v), cujo pH e potencial osmótico foram aferidos. No bioensaio de germinação foram empregadas cinco repetições de 25 sementes distribuídas em placas de petri forradas com papel Germitest, umedecido com 7 mL de extrato ou água e mantidos a 25ºC em B.O.D. por cinco dias. A porcentagem de germinação (PG), velocidade de germinação (VG), índice de velocidade de germinação (IVG) e índice de efeito alelopático (RI) foram determinados. No bioensaio de crescimento inicial, sementes germinadas até atingirem 2 mm de protusão radicular foram transferidas para caixas Gerbox contendo papel Germitest e 15 mL de extrato ou água, permanecendo sete dias a 25ºC em B.O.D. para a avaliação do comprimento da radícula e do hipocótilo, da massa fresca e seca, do conteúdo de água e do teor de clorofila (a, b e total). Todos os parâmetros de germinação (PG, VG, IVG e RI) foram afetados negativamente pelos extratos de P. mikanianum. O crescimento inicial foi influenciado pelos extratos, resultando em redução do comprimento da radícula e aumento do hipocótilo. Além disso, os extratos causaram redução da biomassa fresca e do conteúdo de água a 8% e incrementos dos teores de clorofila b e total a 2 e 4%. Assim, a espécie Piper mikanianum exerce efeito alelopático sobre o rabanete.

This study evaluated the allelopathic effects of an extract from P. mikanianum leaves on the germination and early growth of radish (Raphanus sativus L.). Leaf extracts were prepared at concentrations of 2, 4 and 8%. The pH and osmotic potential of the extracts were determined. Germination bioassay consisted of five replicates of 25 radish seeds distributed in Petri dishes with germitest paper and 7 mL of extract or water, and were kept at 25ºC in B.O.D. for five days. Germination percentage (PG), germination speed (VG), germination speed index (IVG) and index of allelopathic effect (RI) were determined. For bioassay initial growth, seeds were germinated until the protrusion of the radicle was 2 mm and transferred to Gerbox boxes containing germitest paper and 15 mL of extract or water, which were kept for seven days at 25ºC in B.O.D. to evaluate the length of the radicle and hypocotyl, fresh and dry mass, water content and chlorophyll content (a, b and total). Leaf extracts from P. mikanianum negatively affected all parameters examined for germination (PG, VG, IVG and RI). The extracts affected the initial growth, causing reduction of the radicle length and stimulating the growth of the hypocotyl. In addition, the extracts at 8% concentration reduced fresh weight and water content. Extracts at concentrations of 2 and 4% increased the content of chlorophyll b and total chlorophyll. Thus, Piper mikanianum exerted an allelopathic effect on radish.

The flower bud abortion is one of the main problems that limit commercial pear (Pyrus pyrifolia) production in the southern region of Brazil. Insufficient chilling during the dormancy period is known as the main factor of this problem. One of the hypotheses to explain this problem is that the starch mobilization and carbohydrate fluxes to the buds are impeded when mild temperatures occurred during winter. This study compared the total soluble sugars (TSS) and reducing sugars (RS) concentrations, the cell wall acid invertase (CWAI - EC 3.2.1.26) and sucrose-phosphate synthase (SPS - EC 2.4.1.14) activities in wood of branches and floral buds of Japanese pear trees cv. Housui, grafted on Pyrus calleryana and submitted to chilling conditions during the dormancy period. Treatments were: (i) natural conditions; (ii) continuous artificial chilling; (iii) alternating temperatures, and (iv) total chilling privation. TSS and RS contents, as well as CWAI and SPS activities in tissues of branches that received insufficient chilling were lower than those that received sufficient chilling during winter. The starch concentration was superior in wood tissues of branches kept under chilling privation. The chilling privation disturbs carbohydrate mobilization in pear trees, reducing the sucrose synthesis capacity in wood tissues (source) and sucrose importation by the floral buds (sink).

O objetivo foi avaliar os padrões isoenzimáticos de Esterase (EST - EC 3.1.1.1), Fosfatase Ácida (ACP - EC 3.1.3.2), Malato Desidrogenase (MDH - EC 1.1.1.37), Álcool Deshidrogenase (ADH - EC 1.1.1.1) e Glutamato Oxalacetato Transaminase (GOT - EC 2.6.1.1), em sementes e plântulas de dois cultivares de cevada (MN 721 e Scarlett). As sementes foram fornecidas pela empresa Westermann, localizada no município de Piratini, Rio Grande do Sul, onde foi realizado o cultivo da cevada em 2007. Foram colhidas em três épocas com diferentes percentuais de umidade, secas a 13% de umidade e armazenadas em câmara fria. Os cinco sistemas isoenzimáticos analisados apresentaram variações na expressão, principalmente quando comparados entre sementes e plântulas. Concluiu-se que há variação no padrão de expressão das enzimas EST, ACP, MDH, ADH e GOT entre sementes e plântulas. A expressão das enzimas EST e GOT foi pouco e muito influenciada pela época de colheita, respectivamente.

This study aimed to assess patterns of isozyme Esterase (EST - EC 3.1.1.1), Acid Phosphatase (ACP - EC 3.1.3.2), Malate Dehydrogenase (MDH - EC 1.1.1.37), Alcohol Dehydrogenase (ADH - EC 1.1 .1.1) and Glutamate Oxalacetate Transaminase (GOT - EC 2.6.1.1) of two barley cultivars (MN 721 and Scarlett). The seeds were supplied by the company Westermann, located in the Piratini, RS, which had undertaken the cultivation of barley in 2007. Were collected in three seasons with different percentages of moisture and dried at 13% and stored in cold. The five isozyme systems analyzed showed variations in expression, especially when compared to seeds and seedlings. It was concluded that there is variation in the pattern of expression of the enzymes EST, ACP, MDH, ADH and GOT between seeds and seedlings. The expression of EST and GOT enzymes were little and very influenced by cropping season, respectively.

A espécie Achillea millefolium L., conhecida como mil-folhas, é uma planta herbácea, rizomatosa e perene. Sua importância medicinal deve-se às suas atividades antibacterianas, antiinflamatórias, antitumorais, analgésicas e antioxidantes. O efeito da disponibilidade de luz e do nitrogênio sobre o crescimento e produção dessa espécie é pouco conhecido. O objetivo deste trabalho foi avaliar a resposta de A. millefolium L., cultivada sob diferentes níveis de sombreamento e doses de nitrogênio, quanto ao crescimento e à produção de pigmentos fotossintéticos. As plantas foram cultivadas sob três doses de nitrogênio (0, 75 e 150kg uréia ha-1) e submetidas a dois níveis de sombreamento 0% (luz plena) e 75% (sombrite 75%). Adotou-se o delineamento experimental de blocos casualizados com quatro repetições em um fatorial 3x2 (doses de nitrogênio x níveis de sombreamento). O sombreamento influenciou a maioria dos caracteres avaliados, causando uma redução significativa no acúmulo de massa seca da parte aérea (caule + folha + flor), caule, folhas e flores e aumento nos teores de clorofila a, b, total e carotenóides. Os resultados sugerem que a espécie A. millefolium L. possui adaptação à baixa intensidade luminosa, devido às alterações nas características foliares, relacionadas aos teores de pigmentos fotossintéticos.

Achillea millefolium L., known as yarrow, is an herbaceous, rhizomatous and perennial plant. Its medicinal importance is attributed to antibacterial, anti-inflammatory, antitumoral, analgesical and antioxidant activities. The effect of light availability and nitrogen on growth and production of this species is little known. The objective of this study was to evaluate the growth and production of photosynthetic pigments in A. millefolium L. grown under different levels of shading and nitrogen levels. Plants were cultivated under three nitrogen levels (0, 75 and 150kg urea ha-1) and subjected to two levels of shading 0% (full light) and 75% (75% black). The experimental design was delineated in randomized blocks with four replicates in a factorial 3 x 2 (nitrogen levels x levels of shading). The shading influenced most parameters evaluated, causing a significant reduction in dry mass accumulation of shoot (stem + leave + flower), stem, leaves and flowers and increase in levels of chlorophyll a, b, total and carotenoids. Results suggest that Achillea millefolium L. has adaptated to low light intensity, due to changes in leaf traits related to photosynthetic pigments content.