Limite entre as fases I e II de um modelo de embebição de sementes

A knowledge of the imbibition stages shown by different species, is essential in research projects aiming at improvement of seed quality by treatments such as osmotic conditioning, initial wetting, and the use of bioregulators. The objective of this study was to establish a methodology to determine the limit between the first and second stages of the process, considering the model W = f(t) - (a - w0)exp(-kt), using statistical tests. This limit was determined using an asymptotic distribution of an estimator function. The data point beyond which the difference (W*) is no longer significant was determined using Student's T statistics. The model is ; or = (0.434 + 0.00162 t) - (0.434 - w o)exp(-0.121 t), with r² = 0.98 and W* = (0.434 - w o)exp(-0.121 t) fits the utilized data. The calculated t value (27.2 hours) is smaller than the value that was determined considering a 1% value difference between the asymptote and the estimated model as a criterion for the stage change. This two-hour difference corresponds to 0.28% in absorbed water.O conhecimento das fases de absorção de água das diferentes espécies é importante em pesquisas objetivando melhorar a qualidade das sementes, utilizando tratamentos como condicionamento osmótico, pré-hidratação e uso de bioreguladores. O objetivo do presente trabalho foi estabelecer uma metodologia para determinar o limite entre a primeira e a segunda fase do processo, considerando o modelo W = f(t) - (a - w0)exp(-kt), utilizando testes estatísticos. O limite entre as duas primeiras fases do processo de absorção de água pelas sementes, foi determinado utilizando-se a distribuição assintótica de uma função de estimadores. O ponto a partir do qual esta diferença (W*) deixa de ser significativa foi determinado utilizando-se o teste estatístico T de Student. Para os dados utilizados como exemplo, tem-se o modelo ; ou = (0,434 + 0,00162 t) - (0,434 - w o)exp(-0,121 t), com r² = 0,98 e W* = (0,434 - w o) exp(-0,121 t). O valor de t encontrado (27,2 horas) é menor do que o valor determinado, considerando-se como critério para mudança de fase a diferença de 1% entre a assíntota e o valor estimado pelo modelo ajustado. Essa diferença de duas horas corresponde a 0,28% de água absorvida

Germination of Senna Occidentalis link: seed at different osmotic potential levels

The objective of this research was to study the effect of osmotic potential and salinity on the germination of seeds of Senna occidentalis, with and without a change of solutions. The percentage and rates of germination decreased according to decrease of potential, being more drastic when the substitutions of solutions were not made. The largest reductions were observed with the PEG solutions, with and without substitutions

Efeito alelopático de extratos de parte aérea de barbatimão [Stryphnodendron adstringens (Mart.) Coville] na germinação e desenvolvimento da plântula de pepino

Stryphnodendron adstringens (Mart.) Coville (barbatimão), belonging to Mimosaceae family; it is used as ornamental and the wood is used in civil buildings, edification in wet places, lathe and joinery jobs, being very used also in home-made medicine against hemorrhage, diarrhea, hemorrhoids, conjunctivitis, injury cleaning, uterus hemorrhage, ulcerous hurt and excessive oily skin. The objective of this research was to determine the allelopathic potential of an aqueous extract, boiled or not of S. adstringens (Mart.) Coville, in the Cucumis sativus germination and initial development. Thus, the aqueous vegetable extract was extracted from the shoot, which was triturated in 1L of distilled water to 100g of leaf, being the extract filtrated and separated in boiled and not boiled. The treatments used were distilled water (0%) and boiled and not boiled extracts, in the concentrations of 50 and 100%. The cucumber seeds were put to germinate in Gerbox, having filter paper as substrate, which was wet with 25mL from different treatments, in constant temperature of 25°C. The reading germination was accomplished in breaks of 24 hours, for a period of five consequently days after the beginning of the experiment, considering germinated the seeds that showed 2mm of root, approximately. To dry matter determination, the seedlings with five days after the germination were separated in shoot and root, dried during three days to a constant weight in a 60°C forced draft oven. Through results, it can be concluded that the extract of S. adstringens affected more the Cucumis sativus seedling development than the germination, and it didn't show difference if boiled or not

Reguladores vegetais na produção de biomassa e teor de óleos essenciais em Cymbopogon citratus (DC.) Stapf, em diferentes épocas do ano

The purpose of the present research was to evaluate the effect of plant growth regulators in biomass production and essential oil yield content in lemongrass (Cymbopogon citratus (DC.) Stapf), in different seasons. The experiment was conducted on São Manuel Experimental Farm, Faculdade de Ciências Agronômicas, UNESP - Botucatu. Which plants were randomly assigned into blocks to treatments with three repetitions. The treatments consisted of GA3 (50 and 100 mg L-1); Ethrel (100 and 200 mg L-1); CCC (500 and 1000 mg L-1); Alar 85 (1000 and 2000 mg L-1); Accel (20 and 40 mg 0L-1) and control. Four applications of plant growth regulators were realized every three months. After 40 days of each foliar spray, the plants were cut to determine the fresh weight and essential oil yield. The application of plant growth regulators did not increase the biomass production, showing difference among collect periods when the major production was detected at the fourth collect (summer). The greatest essential oil yield was found at the second collect (winter). In the present study, the used concentrations of plant growth regulators did not increase biomass neither essential oil yield

Limit between stages I and II of a seed imbibition curve

O conhecimento das fases de absorção de água das diferentes espécies é importante em pesquisas objetivando melhorar a qualidade das sementes, utilizando tratamentos como condicionamento osmótico, pré-hidratação e uso de bioreguladores. O objetivo do presente trabalho foi estabelecer uma metodologia para determinar o limite entre a primeira e a segunda fase do processo, considerando o modelo W = f(t) - (a - w0)exp(-kt), utilizando testes estatísticos. O limite entre as duas primeiras fases do processo de absorção de água pelas sementes, foi determinado utilizando-se a distribuição assintótica de uma função de estimadores. O ponto a partir do qual esta diferença (W*) deixa de ser significativa foi determinado utilizando-se o teste estatístico T de Student. Para os dados utilizados como exemplo, tem-se o modelo ou =(0,434 + 0,00162 t) - (0,434 - w o)exp(-0,121 t), com r² = 0,98 e W* = (0,434 - w o) exp(-0,121 t). O valor de t encontrado (27,2 horas) é menor do que o valor determinado, considerando-se como critério para mudança de fase a diferença de 1% entre a assíntota e o valor estimado pelo modelo ajustado. Essa diferença de duas horas corresponde a 0,28% de água absorvida.A knowledge of the imbibition stages shown by different species, is essential in research projects aiming at improvement of seed quality by treatments such as osmotic conditioning, initial wetting, and the use of bioregulators. The objective of this study was to establish a methodology to determine the limit between the first and second stages of the process, considering the model W = f(t) - (a - w0)exp(-kt), using statistical tests. This limit was determined using an asymptotic distribution of an estimator function. The data point beyond which the difference (W*) is no longer significant was determined using Student's T statistics. The model is or =(0.434 + 0.00162 t) - (0.434 - w o)exp(-0.121 t), with r² = 0.98 and W* = (0.434 - w o)exp(-0.121 t) fits the utilized data. The calculated t value (27.2 hours) is smaller than the value that was determined considering a 1% value difference between the asymptote and the estimated model as a criterion for the stage change. This two-hour difference corresponds to 0.28% in absorbed water

Estresses hídrico e salino no processo germinativo das sementes de Plantago ovata Forsk. (Plantaginaceae) Water and saline stresses on the germination of Plantago ovata Forsk. (Plantaginaceae) seeds

Plantago ovata é espécie medicinal de grande importância cultivada na Índia, no Irã e no Paquistão. As sementes possuem de 20 a 30% de mucilagem utilizada pelas indústrias farmacêuticas nos tratamentos de constipação crônica, câncer intestinal e amebíase. A Índia é o principal exportador mundial das sementes de Plantago ovata, tendo o produto comercial com essas sementes, no Brasil, o nome de Agiolax. O objetivo deste trabalho foi avaliar os possíveis efeitos dos estresses hídrico e salino na germinação de sementes de Plantago ovata. As sementes foram colocadas para germinar em papel umedecido com 15 mL de soluções nos potenciais osmóticos de 0,0; -0,2; -0,4; -0,6; e -0,8 MPa, induzidos com polietileno glicol (PEG 6000), NaCl e CaCl2. O experimento constou de quatro repetições com 50 sementes cada, na temperatura de 25 ºC, na presença de luz. A análise dos resultados permitiu a conclusão de que o estresse hídrico acarreta maior redução na porcentagem e velocidade de germinação das sementes de P. ovata do que o estresse salino, e, independentemente da substância utilizada para indução do estresse, o limite para germinação está entre -0,4 e 0,6 MPa.<br>Plantago ovata is a medicinal species of great importance cultivated in India, Iran and Pakistan.The seeds contain 20 to 30% of mucilage, used by the pharmaceutical industry for the treatment of chronic constipation, intestinal cancer and amoeba. India is the main exporter of Plantago ovata seeds, worldwide. In Brazil, this species has been given the corporate name of Agiolax. This work aimed to evaluate the possible effects of water and salt stresses on the germination of Plantago ovata seeds. The seeds were put to germinate in paper moistened with 15mL of solutions with the potentials of 0.0; -0.2; -0.4; -0.6 and -0.8MPa, induced with polyethylene glycol (PEG 6000), NaCl and CaCl2. Each experiment consisted of 50 seeds, 4 repetitions, and temperature at 25ºC in the presence of light. The results allowed the conclusion that water stress causes a greater reduction in the percentage and speed of germination of P. ovata seeds than saline stress, regardless of the substance used for stress induction, germination limit was-0.4 to -0.6MPa

Germinação de sementes de Plantago ovata Forsk. (Plantaginaceae): temperatura e fotoblastismo Germination of Plantago ovata Forsk. (plantaginaceae) seeds: temperature and photoblastism

Plantago ovata é espécie medicinal de grande importância cultivada na Índia, no Irã e no Paquistão. Suas sementes possuem de 20 a 30% de mucilagem, utilizada pelas indústrias farmacêuticas nos tratamentos de constipação crônica, câncer intestinal e amebíase. A Índia é o principal exportador mundial de sementes de Plantago ovata, e o produto comercial originado dessas sementes, no Brasil, leva o nome de Agiolax. Este trabalho teve como objetivo verificar o efeito da luz e temperatura na germinação de sementes dessa espécie. Para tanto, foram utilizadas quatro repetições com 50 sementes cada uma, colocadas para germinar em papel-filtro umedecido com 12 mL de água destilada, nas temperaturas de 5 a 35 ºC, com intervalos de 5 ºC, na ausência e presença de luz. As sementes germinaram tanto na luz quanto no escuro e apresentaram comportamento de fotoblásticas neutras na faixa de temperatura de 10 a 25 ºC, com faixa ótima de 20 a 25 ºC, em que ocorreram maiores porcentagens e velocidade de germinação.Plantago ovata is a medicinal species of great importance cultivated in India, Iran and Pakistan.The seeds are known to contain 20 to 30% of mucilage, and are used by pharmaceutical industries in the treatment of chronic constipation, intestinal cancer and amoeba. India is the main world-wide exporter of Plantago ovata seeds.In Brazil, this species is known by the corporate name of Agiolax. The present work aimed to verify the effect of light and temperature on the germination of seeds of this species. Thus, 4 replications were used, each with 50 seeds put to germinate in filter paper humidified with 12mL distilled water, at 5 and 35Cº,at intervals of 5ºC, in the absence and presence of light. The seeds germinated both in the light and dark, presenting a neutral photoblastic behavior at the temperature range of 10 and 25ºC, with optimal range at 20 and 25ºC, when higher percentages and germination speed were verified