<em>Chamaecrista </em>Moench pertence à família Leguminosae, subfamília Caesalpinioideae. Diante da escassez de informações sobre os mecanismos de germinação das espécies, objetivou-se com esse trabalho avaliar a eficiência de tratamentos pré-germinativos para superação de dormência de sementes de <em>Chamaecrista debilis</em>. Considerando-se as características aparentes das sementes em relação à espessura do tegumento e sua dureza, foi efetuado teste de germinação com 12 tratamentos: testemunha- sementes intactas, escarificação mecânica com lixa d’água n. 80, imersão em água a 100<sup>o</sup>C por 5, 10, 15, 30 e 60 segundos e imersão em ácido sulfúrico concentrado por 5, 10, 15, 30 e 60 segundos . Foram avaliadas as porcentagens de germinação das sementes e o índice de velocidade de germinação, além do teor de água das sementes de <em>Chamaecrista debilis</em>. Utilizou-se o delineamento inteiramente casualizado com quatro repetições, e as médias foram comparadas pelo teste de Scott-Knott, a 5% de probabilidade. As sementes de <em>Chamaecrista debilis </em>apresentaram grau de umidade de 11,71%. Os tratamentos com água a 100ºC por 5, 10 e 15 segundos e ácido sulfúrico por 15 segundos foram os mais eficientes em promover a germinação, indicando que a dormência nessa espécie também deve-se à impermeabilidade do tegumento.
The physical, physiological and biochemical changes during the development until the dispersal of rubber tree seeds were evaluated with the purpose of estimating the point at physiological maturity. A total of 30 plants were selected at different points in a commercial planting area and had their flowers marked during the anthesis and every 15 days after marking. Fruits and seeds were collected for analysis of moisture content, dry matter, diameter and length. Details of the anatomy ultra-structure of the seeds were evaluated. The seed emergence, emergency speed index, heat resistant proteins and oxidative stress enzymes were examined. It was observed that fruits reached maximum size at 120 days after anthesis and seeds at 150 days. The seeds acquired germination capacity after 150 days. At 175 days, they presented the highest percentage of dry matter and lowest moisture, in addition to a higher percentage of germination and vigor. Therefore, it was possible to conclude that the physiological maturity of the rubber tree seeds occurs at 175 days after anthesis, and coincides with its maximum physiological quality. At 175 and 180 days post-anthesis, there is a greater expression of heat resistant proteins as well as low molecular weight and greater oxidative stress enzyme activity.
ABSTRACT. With the imminence of global climate changes that affect the temperature and the rainfall uniformity, it is growing the concern about the adaptation of crops to the water deficit. Thus, the objective of this study was to evaluate alterations in physiological and enzymatic mechanisms during the germination process of sesame seeds under different water availability. To simulate the water restriction we used PEG6000, a high molecular weight molecule that does not penetrate the seed structure but allows different osmotic potentials. The treatments were -0.1, -0.2, and -0.3 MPa, and the control. Germination, first-count germination, germination velocity index, and length and dry mass of the hypocotyl and radicle were performed. The seeds were weighed before and after treatments every 3 h. After each weighing, 100 seeds were taken for analysis of the enzymes alcohol dehydrogenase (ADH), malate dehydrogenase, esterase, catalase (CAT), superoxide dismutase (SOD), isocitrate lyase (ICL), and glutamate dehydrogenase (GTDH). The statistical design was completely randomized with five replications. PEG6000 prolonged ADH activity during the beginning of germination, maintaining the anaerobic metabolism for longer. Subsequently, their activity was reduced, as well as ICL, favoring the deterioration of the seeds that take the time to germinate. Behavior was evidenced by the appearance of SOD, CAT, and GTDH isoforms after 24 h of imbibition when water restriction was imposed. Therefore, the PEG600 is efficient in simulating water deficit conditions in future scenarios of climate change, offering impotent information regarding the germination behavior of the plants under these conditions.
The objective of this study was to evaluate the enzymes expression during the seeds germination process of ever-lasting species Comanthera elegans and Comanthera bisulcata. For the evaluation of the seeds physiological potential, the germination test and index of germination speed were performed. The expression of enzymes esterase (EST), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), superoxide dismutase (SOD), catalase (CAT) and endo-β-mannanase during the germination process were evaluated. The expression of these enzymes was evaluated in dried seeds, in the protrusion, in the emergence of the primal leaf, at the beginning of the formation of normal seedling and dormant seeds at the end of the germination process. To the extent that the germination process occurs in the species C. bisulcata and C. elegans there is greater expression of the enzyme CAT and lower of the enzyme EST. There is variation in the expression of the enzymes SOD, ADH and MDH in seeds of both species during the germination process. The enzyme endo-β-mannanase presents greater activity in seeds with radicle protrusion in the two studied species.
RESUMOObjetivou-se, neste trabalho, avaliar o efeito de seis espécies de plantas daninhas cultivadas em competição com plantas de pinhão-manso (Jatropha curcas L.) em um Latossolo Vermelho-Amarelo (LVA) e um Neossolo Quartzarênico (NQ). Para tal foi realizado experimento no delineamento em blocos casualizados com quatro repetições. Os tratamentos foram arranjados em esquema fatorial 2x6, sendo o primeiro fator representado por dois tipos de solo (LVA e NQ) e o segundo pelas seis espécies de plantas daninhas cultivadas juntamente com a cultura (Ageratum conyzoides L., Bidens pilosa L., Cenchrus echinatus L., Commelina benghalensis L., Emilia fosbergii N.), além de testemunha sem competição. As espécies daninhas afetaram negativamente o crescimento de pinhão-manso, tanto no LVA quanto no NQ. Dentre as espécies avaliadas, C. echinatus e E. fosbergii promoveram maior efeito negativo quando em competição com plantas de pinhão-manso, para a maioria das variáveis testadas. As plantas de J. curcas apresentaram melhor tolerância à perda de matéria seca da parte aérea quando em competição sob LVA, situação contrária para o sistema radicular quando referida oleaginosa foi cultivada em amostras de NQ. O crescimento do pinhão-manso é afetado pela competição com as plantas daninhas mas a magnitude deste efeito é dependente da espécie competidora e do solo utilizado. Palavras-chave: interferência, Jatropha curcas L., potencial competitivo Jatropha growth in competition with weeds in two types of soil ABSTRACTWe aimed with this study to evaluate the effect of six weed species grown in competition with plants of jatropha (Jatropha curcas L.) in Red Yelow Oxisol (LVA) and Quartizarenic Neossol (NQ). The experiment was installed in randomized blocks design with four replications. The treatments were arranged in a 2x6 factorial design, with the first factor represented by two soil types (LVA and NQ) and six weed species (Ageratum conyzoides L., Bidens pilosa L., Cenchrus echinatus L., Commelina benghalensis L., Emilia fosbergii N.) grown along with the crop, plus a control with no competition. Presence of weeds negatively affected growth of jatropha both in LVA and NQ. Among the studied species, C. echinatus and E. fosbergii promoted greater negative effect on jatropha, for most of the variables tested. J. curcas showed better tolerance to reductions in shoot dry matter accumulation when in competition under LVA, a situation contrary to the root system when this oil crop was grown in NQ.soil The growth of jatropha is affected by competition with weeds, but the magnitude of this effect is dependent on the weed species and type of soil.
The objectives in the present work were to identify maize double haploids one generation after chromosome duplication through the evaluation of phenotypic characteristics in thr field, flow cytometry and molecular markers SSR. The seeds used in the present study were obtained from a cross between four simple hybrids (DKB393, GNS 3225, GNS 3264, GNS 3032) and the KEMS inducer of gymnogenetic haploidy, used as a male parent. Seeds from this crossing were selected according to the R-Navajo marker and those considered haploid, were submitted to two different chromosome duplication protocols. Plants that survived to the chromosome duplication protocols were acclimatized in greenhouse and later transplanted to the field. After self-fertilization of the DH0 plants, the DH1 seeds obtained were seeded in the field, divided into treatments according to the parental and duplication protocols. At the vegetative stage V4 of the DH1 seedlings, leaf tissue samples were collected to identify ploidy via flow cytometry and DNA analyzes using microsatellite markers. These results were confronted with the morphological characteristics of the future DH1 plants developed in the field, evaluated with the use of descriptive tools. Statistical analyzes were performed using the generalized linear modeling approach and the exploratory and inferential analyzes of datas, by the use of graphical resources, barplot and boxplot. For the analysis of variance, were used the Student-Newman-Keuls test, and the Pearson's correlations. It was not observed uniformity of phenotypic characteristics of plants subjected to duplication protocols in the field and the use of descriptive tools in the morphological analysis of adult maize plants must be done carefully to avoid the wrong classification of determined genotypes related to the ployd. Flow cytometry must be used as screening in the identification of possible DH´s and the molecular markers SSR can be used to prove the genetically inherited KEMS lineage and also to identify the double-haploid corn plants.
Temperature is one of the most important factors in the germination process, which influences the absorption of nutrients required for growth and development of the plant, germination uniformity, and seed vigor maintenance. Low temperatures can result in deformation of the leaves and the apex of the plant, and high temperatures hamper the development of them. The objective of this work was to evaluate the ideal temperature values for germination in each genetic material used, highlighting the most suitable for each condition. The experiment was conducted at the Central Seed Laboratory at the Department of Agriculture of the Lavras Federal University, where germination percentage, first germination count, seedling emergence and emergence speed were evaluated. The experimental design was completely randomized, with a factorial scheme of 4 × 5, in which it was analyzed four lines (L30, L64, L63, and L91) at five different germination temperatures (15, 20, 25, 30 and 35 ºC). An analysis of variance was done and for the comparison between means, the Scott Knott test was used, at a 5% probability. It can be observed that the lines L63 and L91 were more susceptible to low germination temperatures and lines L30 and L64 do not tolerate high temperatures. Also, the evaluation of temperature-controlled substrate germination proved to be a promising technique to identify tolerant and susceptible lines for germination in both high and low temperatures.
Production of soybeans with high physiological quality is important to ensure the productivity of improved plant populations. The objective of this work was to select soybean genotypes for high physiological quality of seeds, through germination and vigor tests, and to study gene expression by transcripts and proteins. In a first trial, seeds of 12 soybean cultivars were evaluated and selected six cultivars with contrasting physiological quality levels. At the protein level, the isoenzyme systems alcohol dehydrogenase (ADH), malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), sorbitol dehydrogenase (SDH), superoxide dismutase (SOD), catalase (CAT), isocitrate lyase (ICL), esterase (EST), glutamate oxaloacetate transferase (GOT), and heat-resistant proteins were evaluated. For the transcript levels, the real-time PCR technique (qRT-PCR) was used, and the genes coding for the SOD, CAT, MDH, PGI, ICL and PRX enzymes were studied. The germination and vigor tests classified the seeds of cultivars CD201, CA115 and MS8400 as high quality, while the cultivars Syn1263, Syn1279 and CD202 were classified as of low quality. The enzymes involved in the process such as dehydrogenase and phosphoglucose isomerase, are promising markers for assessing the physiological quality of soybean seeds. Higher expression of peroxiredoxin enzyme is related to the low physiological quality of soybean seeds.
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