Average Germination Time Research Articles

Efeito da Temperatura e do KNO3 na Germinação de Acnistus arborescens (Solanaceae)

RESUMO A propagação de Acnistus arborescens (fruto-do-sabiá) usualmente é feita através de estacas, devido a baixa taxa de germinação de suas sementes. O objetivo deste trabalho foi estudar o efeito da temperatura e do estimulante nitrato de potássio (KNO3) na germinação do fruto-do-sabiá. O experimento foi realizado utilizando quatro regimes de temperatura (20, 25, 30 e 20-30 °C), com e sem nitrato de potássio, em delineamento inteiramente casualizado com quatro repetições de 50 sementes cada. Foram avaliados a porcentagem, o índice de velocidade e o tempo médio de germinação. Nas temperaturas constantes, o KNO3 favoreceu a germinação, sendo as maiores porcentagens (>68%) obtidas nas temperaturas de 20 °C e 25 °C. A temperatura alternada de 20-30 °C aumentou a porcentagem de germinação, sem a adição de KNO3, portanto além da propagação vegetativa. A produção de mudas a partir de sementes é viável.

Seed germination of medicinal plant, fennel (Foeniculum vulgare Mill), as affected by different priming techniques.

Reduced seed germination is among the most important factors adversely affecting crop stand and subsequent plant growth. Fennel (Foeniculum vulgare Mill) is an important medicinal plant with poor seed germination rate, occasionally. It is accordingly pertinent to find methods which can enhance fennel seed germination and remove the barriers of dormancy breaking. The present experiments studied the effects of two different priming (cold moist stratification and osmopriming) and 14 dormancy breaking techniques (hormonal, osmopriming, biopriming, chemical priming, and hydropriming) on the seed germination and seedling growth of two different fennel genotypes under growth chamber conditions. In the first and second experiment, the priming techniques including the time lengths of cold moist stratification (0, 15, 30, and 45days) and the concentrations of polyethylene glycol 6000 (PEG6000, osmopriming at -0.99, -1.35, and -2.33MPa) were used as the main plots. However, in both experiments, the dormancy breaking techniques and fennel genotypes were factorially combined and used as the subplots. Different seed- and seedling-related parameters including germination (%), plumule, radicle and seedling length, average germination time, rate and homogeneity of germination, and seed vigor index were determined. Both priming techniques were efficient on the enhancement of seed germination and seedling growth. Among the dormancy breaking techniques, Aminol Forte (biopriming), kadostim (biopriming), benzyl adenine + kinetin (biopriming), distilled water (hydropriming), gibberellin + kinetin (hormonal priming), and benzyl adenine + kinetin + gibberellin (biopriming) were the most effective ones. The related concentrations were equal to 100mg/l, 10(-5)M, and 0.4%. The fennel genotypes reacted significantly different under priming conditions. It is possible to enhance seed germination and seedling growth of fennel using priming and dormancy breaking techniques, which is useful for the increased production of fennel under different conditions. The results indicate that bio and hydropriming techniques were among the most effective ones, which significantly increased seed germination and seedling growth, and removed the seed dormancy barriers.

GERMINAÇÃO E CRESCIMENTO INICIAL DE Machaerium brasiliense VOGEL (FABACEAE) EM CASA DE VEGETAÇÃO

Machaerium brasiliense Vogel é uma espécie arbórea, conhecida popularmente como pau-sangue, jacarandá-bico-de-pato e sapuva. Com o objetivo de verificar a germinação, sementes de M. brasiliense foram mantidas sob temperatura de 20°, 25° e 30 °C, em câmara de germinação com fotoperíodo de 12h ou escuro contínuo. Para análise do crescimento inicial, avaliaram-se, aos 90, 180, 270 e 360 dias após o transplante (DAT), a altura, o comprimento da raiz, a massa seca da parte aérea, da raiz e total e o número de folhas de plantas mantidas em casa de vegetação. A presença ou ausência de luz não influenciou o desempenho das sementes, observando-se maior porcentagem de germinação (PG) para as sementes submetidas a 20 e 25 °C, o mesmo sendo verificado para o parâmetro índice de velocidade de germinação (IVG). O menor tempo médio de germinação (TMG) foi observado a 30 °C. Em relação aos parâmetros de crescimento, os maiores valores foram obtidos aos 270 e 360 DAT, não ocorrendo diferença estatística entre esses dois períodos de avaliação. A presença de nódulos radiculares foi observada a partir dos 180 DAT.

Exogenous nitric oxide-induced germination associated with pinitol content in Hymenaea courbaril low vigour seeds

Nitric oxide (NO), a membrane-permeable free radical, has been reported as a potent signalling molecule in animals and plants. It is commonly accepted that NO induces dormancy release and promotes seed germination. However, few studies were carried out with seeds of tropical arboreal species, which present distinct characteristics compared to temperate model seeds, in order to confirm a broad role of NO in seed germination. To our knowledge, this is the first work to investigate the role of exogenous NO on the germination of seeds accumulating cell wall polysaccharides as the main carbon reserve. The aim of this study was to evaluate the effect of NO donors on germination and primary metabolism of seeds from Hymenaea courbaril L., a leguminous tree species from Neotropical rainforests. Seeds with distinct vigour rates, namely lower vigour seeds (LVS) and higher vigour seeds (HVS), were imbibed in distilled water (control) and NO donor solutions, and selected parameters such as germination rate and normal seedlings, root growth, and metabolic profile were evaluated. Our results show that NO donors reduced the average time of germination and improved normal seedling development of LVS, without affecting the final germination rate. This treatment also induced changes in the relative proportion of soluble sugars and cyclitols identified by gas chromatography–mass spectrometry analysis. Taken together, our data suggest that exposure to the NO donor partially revert deterioration on naturally ageing seeds, possibly through the modulation of pinitol content, and open new perspectives to enhance the existing knowledge on the role of NO on seed viability.

Seed germination after passing through gastrointestinal tract of bats (chiroptera, phyllostomidae)

The aim of this study was to evaluate seed germination of Piper, Solanum, Cecropia and Ficus species after their passage through the gastrointestinal tract of frugivorous bats - Artibeus lituratus, Platyrrhinus lineatus, Carollia perspicillata and Sturnira lilium. Both bats and fruits/fruit cluster samples were obtained in the Parque Estadual Mata do Godoy, Londrina, Brazil. For each plant species, we considered the control and four treatments, made up by the seeds obtained from the feces of each species of bat: (1) A. lituratus, (2) P. lineatus, (3) C. perspilata and (4) S. lilium. Two hundred seeds were used for each treatment and were germinated at the same time, randomly distributed in four containers. The germination data were used to calculate the rate and the average germination time. In only two species, pachystachya Cecropia and Ficus eximia, the passage through the gastrointestinal tract of animals produced no significant change. While the remaining six species had significant differences in the rates and / or average time of seed germination after passage through the gastrointestinal tract of at least one species of bats. Moreover, food preference of bat species for one plant species did not significantly change seed germination in relation to other plants. We conclude that over the evolutionary process, diffuse coevolution did not favor the alteration of germination patterns by the food preference of bats. However, bats do appear to alter the rate and time of seed germination in plants, helping their establishment, besides being good dispersers even of plants whose germination is not affected. The conclusion is that over evolutionary process, diffuse co-evolution did not favor changing germination standards for food preference of bats. However, it was observed that bats modify the rate and germination time of plants assisting its establishment, besides being good dispersers, even of the species where germination has not been changed.

English

The guinea grass Panicum maximum, an African grass, is one of the main forage grasses in tropical America. Its propagation is mainly carried out by seeds, but seed dormancy hampers good pasture establishment. The aim of this study was to evaluate the use of heat treatment to overcome seed dormancy of P. maximum cultivars Milenio, Tanzânia and Mombaca. Seeds of each cultivar have been subjected to heat treatments at temperatures of 50, 60 and 70°C with exposure time for 5, 10 and 15 h. Afterwards, they were placed in germination test. The data were subjected to analysis of variance and, when significant, polynomial regression was performed, with up to 5% of probability. The variables analyzed were germination percentage, germination speed index (GSI) and average germination time (AGT). P. maximum seeds of different cultivars showed distinct responses to heat treatment. The cultivar Tanzânia responds positively to different combinations of temperature and periods of seeds exposure, and the treatment at 70°C for about 8 h is recommended to overcome dormancy with better germination performance. For cultivar Milenio, it is recommended the exposure of seeds at 70°C for 15 h. Cultivar Mombaca is negatively influenced by the heat treatment, so this treatment is not recommended. Key words: African grasses, germination, pasture, temperature.

Estresse osmótico na germinação de sementes de Petiveria alliacea L.

RESUMOO trabalho teve como objetivo verificar os efeitos dos estresses hídrico e salino na germinação de sementes de Petiveria alliacea , bem como definir os limites máximos de tolerância da espécie a esses estresses. As sementes foram submetidas aos agentes osmóticos NaCl, CaCl2 e PEG nos potenciais à 0; -0,1; -0,2; -0,3; -0,4; -0,5; -0,6; -0,7; -0,8; -0,9 e -1,0 MPa sob temperatura constante de 25˚C e fotoperíodo de 12 horas, com avaliações diárias durante 30 dias. As variáveis analisadas foram porcentagem de germinação, índice de velocidade de germinação, tempo médio de germinação, índice de sincronização e frequência relativa da germinação. As sementes de P. alliacea sob estresse osmótico apresentam menor porcentagem e velocidade de germinação com a redução dos potencias osmóticos, principalmente com CaCl2. Em potenciais osmóticos mais negativos que -0,4; -0,5 e -0,7 MPa, respectivamente nos agentes CaCl2, NaCl, e PEG, não ocorre germinação. O padrão de distribuição da frequência relativa aumentou a polimodalidade, o tempo médio de germinação e o índice de sincronização da germinação com a redução dos potencias osmóticos.

Métodos para superação de dormência em sementes de tomateiro arbóreo (Solanum betaceum)

RESUMO O tomateiro arbóreo (Solanum betaceum) é espécie pouco conhecida, porém, apresenta frutos com enorme potencialidade de mercado, uma vez que podem ser consumidos tanto in natura como na forma industrializada. Contudo, um dos entraves para essa potencialidade se tornar realidade é a produção de mudas. A propagação dessa espécie ocorre por meio de sementes, mas, normalmente, a germinação requer tempo, principalmente sob condições de estresse. Objetivou-se verificar se existe dormência em sementes de tomate arbóreo e a técnica adequada para obter germinação rápida e uniforme. O delineamento foi o inteiramente casualizado, em esquema fatorial 5 x 2 (métodos para superação de dormência x luz), com 4 repetições de 50 ou 60 sementes, de acordo com o ciclo produtivo. Os métodos avaliados foram estratificação, hidrocondicionamento, condicionamento osmótico com GA3 e controle, com e sem luz. Também foram avaliados a germinação e o índice de velocidade de germinação, bem como o início e tempo médio de germinação. A utilização de GA3 na concentração de 100 mg L-1 ou 300 mg L-1 é recomendada para a germinação de sementes de tomate arbóreo.

Electrical conductivity test in Piptadenia moniliformis Benth. seeds

The electrical conductivity test is a quick, practical and objective test force; however, its effectiveness varies according to the species, quantity of seed, water volumes, soaking temperature, among other factors. The objective of this study was to evaluate the physiological quality of P.moniliformis seeds lots by means of the electrical conductivity test, testing different methodologies. For this, two lots were tested in three quantities of time (25, 50 and 75 seeds) and nine soaking times (2, 4, 6 , 12, 24 , 36, 48, 60 and 72 hours) in three volumes of water (50, 75 and 100 mL) at 25 °C. To evaluate the initial quality of the lots, germination percentage, germination speed index, average time of germination, length and dry mass of seedlings were determined. The use of the electrical conductivity test of P. moniliformis seeds is recommended using 75 seeds in 75 mL of water for 2 hours at 25 °C or seeds in 50 mL distilled water with 50 seeds per 6 hours at 25 °C.

Germinação de Sementes de Amor-Perfeito Submetidas a Diferentes Períodos de Exposição e Concentrações de GA3

Viola x wittrockiana (Amor-Perfeito) é uma planta híbrida utilizada em ornamentação, na culinária e na indústria farmacêutica. Com o objetivo de analisar a influência do Ácido Giberélico (GA3) na germinação de sementes de Amor-Perfeito, realizou-se embebição em três concentrações desse ácido (5, 10 e 20 mg.L-1) por quatro períodos diferentes: 30, 60, 120 e 180 minutos. Após os tratamentos, as placas foram mantidas em Câmara de Germinação (B.O.D.), sob temperatura de 25 °C ± 2 e luz branca de lâmpadas fluorescentes a 116 µmol.m-2.s-1, com fotoperíodo de 12 h. O monitoramento foi diário e os dados obtidos foram utilizados para o cálculo da germinabilidade, índice de velocidade de germinação e tempo médio de germinação. O melhor tratamento para germinabilidade e tempo médio de germinação foi a concentração de 5 mg.L-1 durante 30 minutos de exposição e os melhores índices de velocidade de germinação foram obtidos com 180 minutos de exposição em todas as concentrações de GA3.

Avaliação de extratos das espécies Helianthus annuus, Brachiariabrizanthae Sorghum bicolor com potencial alelopático para uso como herbicida natural

RESUMO Objetivou-se avaliar o potencial alelopático de extratos aquosos de braquiária, girassol e sorgo na germinabilidade e crescimento inicial de alface (Lactuca sativa L.) visando o uso destes extratos como herbicida natural. O estudo foi realizado no Laboratório de Fisiologia Vegetal da Universidade Federal do Recôncavo da Bahia. Foi instalado um experimento no delineamento inteiramente casualizado, com 4 tratamentos e 6 repetições. Os tratamentos foram extratos de braquiária, girassol, sorgo e como controle, água destilada. Os extratos foram obtidos, utilizando 200 g de material vegetal para 1000 mL de água destilada. Os aquênios de alface foram distribuídos em caixa gerbox contendo duas folhas de papel germitest umedecidas com os tratamentos e levadas para câmara de germinação. A germinação foi acompanhada diariamente. Foram avaliados o tempo médio de germinação e, após dez dias, o crescimento inicial, medindo-se o comprimento da parte aérea (CPA) e o comprimento do sistema radicular (CSR). Os dados gerados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey. Com base nos resultados, os extratos de braquiária, girassol e sorgo não afetaram a germinação da alface, mas os de braquiária e sorgo aumentaram o tempo médio de germinação. Os extratos causaram aumento na parte aérea, diminuíram o crescimento do sistema radicular e a formação de plântulas normais. Por causarem inibição no crescimento do sistema radicular da alface, apresentam potencial para serem utilizados como herbicidas naturais.

TEMPERATURE AND SUBSTRATE INFLUENCES ON SEED GERMINATION AND SEEDLING FORMATION IN Callisthene fasciculata Mart. (VOCHYSIACEAE) IN THE LABORATORY1

ABSTRACTCallisthene fasciculata Mart. is a tree belonging to the Vochysiaceae family. Its wood is moderately heavy and resistant and used to make poles, beams, and other structures. The aim of this work was to evaluate seed germination and the initial growth of seedlings of C. fasciculata at different temperatures and in different substrates. Seeds were collected from fruits in the Pantanal de Miranda, Mato Grosso do Sul state, Brazil. In one experiment, the seeds were subjected to constant temperatures of 20, 25, 30 and 35 °C and to alternating temperatures of 20-30 and 25-35 °C (on paper substrate). In another experiment, the seeds were subjected to temperatures of 20 and 25 °C on three substrates (sand, vermiculite and between paper) in a germinator. The experiment had a randomized design, with four replicates of 25 seeds per treatment. The F-values obtained for germination indicated no significant effect of substrate or temperature on the final germination percentage. The analyses revealed no effect of a treatment interaction (temperature x substrate) on either germination or average germination time; however, a treatment interaction effect was observed on the germination speed index. The treatment combinations yielding the best performance were between paper substrate at 20 °C and sand substrate at 25 °C. There was a significant effect of the interaction between temperature and substrate on seedling growth, with increased root growth observed in the between paper substrate at 25 °C and increased aerial component growth in both sand at 20 °C and vermiculite at 25 °C. The between paper treatment at 25 °C yielded the greatest final seedling size. Between paper is the most recommended substrate for the production of seedlings due to its ease of handling and lower probability of contamination.

Effects of 6-Benzylaminopurine (BAP) Treatment on Seed Germination and Seedling Vigour of Endemic Herb Exacum trinervium L. in Sri Lanka: Conservation strategy

Based on the scientific information available, E. trinervium is currently of conservation concern since it shows poor seedling growth even under satisfactory seed germination. Ex-situ cultivation is therefore recommended as a conservation strategy. This study aimed to (i) investigate the effective pre-sowing 6-Benzylaminopurine (BAP) treatment that enhances the seed germination and seedling vigour and (ii) to study morphological traits that can be used in assessing healthy seedlings of E. trinervium. The experiment was conducted in a completely randomized design under both laboratory and green house conditions with BAP concentrations of 1.0, 2.0 and 3.0 mgL-1 as pre-sowing treatments and distilled water as the control with different exposure durations i.e. 18, 24 and 30 hours. The results showed that there was no significant effect of BAP treatments on seed germination percentage under laboratory and nursery conditions. The lowest average mean germination time (MGT) was obtained 24 h exposure duration for the green house condition. Seedling dry weight and seedling Vigour Index (SVI) were significantly (P0.05) higher for BAP concentration of 3.0 mgL-1 under 24 h exposure duration. Growth parameters i.e. number of leaves, plant height, root length, number of primary roots, dry weight and fresh weight of E. trinervium were significantly (P<0.05) induced by BAP concentration and exposure duration. Accordingly, BAP concentration of 3.0 mgL-1 under 24 h exposure duration proved to be the optimum BAP treatment for the increase of seedling vigour of E. trinervium under the green house conditions. Therefore, the present study suggests that BAP treatment may be involved metabolically in the stimulation of germination and then to increase the seedling vigour of E. trinervium. Journal of the University of Ruhuna 2015 3(1): 14-20

EFEITO DA TEMPERATURA E LUZ NA GERMINAÇÃO DE SEMENTES DE <i>Dalbergia cearensis</i> Ducke

http://dx.doi.org/10.5902/1980509816613O conhecimento do comportamento germinativo de uma espécie vegetal é de significativa importância para a adoção de técnicas que visam sua propagação. O trabalho avaliou o processo germinativo de sementes de Dalbergia cearensis Ducke na presença e ausência de luz, submetidas a temperaturas constantes de 20, 25, 30, 35 e 40 ºC e alternada de 20-45 ºC, sob fotoperíodo de 12 horas e escuro contínuo. As variáveis avaliadas foram: a porcentagem, a velocidade e o tempo médio de germinação. As sementes germinaram na presença e na ausência de luz, com as maiores porcentagens de germinação alcançadas nas temperaturas de 25, 30 e 35ºC. Desse modo, para desencadear o processo germinativo dessa espécie, não há necessidade da incidência ou ausência de luz, podendo-se caracterizar suas sementes como fotoblásticas neutras. A germinação foi nula no regime de temperatura alternada. A faixa ótima de temperatura entre 25 a 35ºC aumenta a velocidade e reduz o tempo médio de germinação de sementes de D. cearensis, tanto para o escuro quanto para luz.

EFEITO DO SUBSTRATO BOVINO NA GERMINAÇÃO DE PIMENTA BIQUINHO (CAPSICUM CHINENSE) IRRIGADO COM ÁGUA RESIDUÁRIA

The Brazilian semiarid region characterized by prolonged drought and poor rainfall distributed, reducing the quality and quantity of water available. In this context, the present study performed in a protected environment at the Federal University of Campina Grande aiming to analyze the germination of pepper pout with bovine substrate irrigated with different levels of wastewater treated.The treatments consisted on 5 water levels (N) using the water supply and wastewater derived from an upflow anaerobic (UASB) based on plant water requirement (NH), as follows: 100% of NH (N5) 80% of NH (N4), 60% of NH (N3), 40% of NH (N2) and 20% of NH (N1). Germination percentage (PG) the germination speed index (GSI ), mean velocity (MV) and the average time (Tm) of germination were evaluated, on biquinho pepper (BRS Moema). The germination percentage for water supply averaged 42.3% and 46.5% for wastewater. For water levels applied the average germination rate of biquinho pepper ranged from 0.086 to 0.089. The germination of pepper had better results with the use of water residuaria. O reuse of water in semi-arid regions is a viable alternative reducing costs and providing nutrients culture.

The effect of the temperature and light on the seed germination of Dalbergia cearensis Ducke

The knowledge about the germination behavior of a plant species is major important to the adoption of the techniques that aim its spreading. The work analyzed the seed germination process of Dalbergia cearensis Ducke in the presence and absence of light, that was subjected to constant temperatures of 20, 25, 30, 35, 40 oC and alternating temperatures of 20 - 45 oC, all under a photoperiod of 12 hours and continuous darkness. The variables evaluated were: the percentage, the speed and the medium time of the germination. The seeds germinated in the presence and absence of light and the higher percentages of germination were 25, 30 and 35 oC. Thus, to trigger the germination process of this species, there is no need of exposure or absence of light. So they can be characterized as neutral photoblastic seeds. No germination was observed at alternating temperatures of 20 oC to 45 oC. The optimum temperature range between 25 to 35 oC increases speed and reduces the average time of germination of D. cearensis for both the dark and for light.

Effects of submergence in water on seed germination and vigor of the Copaifera lucens (Fabaceae) seedlings

We analyzed the tolerance of Copaifera lucens seeds to submersion in water to assess the use of this species for direct seeding in riparian forest restoration programs. Seeds were submerged in water for 2, 4, 8, 16 and 32 days or not submerged (control = 0 days of submergence). For the control and at the end of each period of submersion, germination and seedling vigor tests were carried out. For germination tests, seeds were sown in plastic pots containing sand and kept in laboratory conditions. The percentage of seed germination, the germination rate and the average germination time were analyzed. For seedlings, total biomass, leaf area, leaf mass per area and leaf area ratio were analyzed. Submersion time drastically affected the dissolved oxygen content and seed germination. Between 4 and 8 days of submersion there was a decrease from 83.8% to 15.6% in the germination percentage. No seed germination occurred after 16 days of submersion. Although there was a significant decrease in the percentage of seed germination between 4 and 8 days of submersion, seedling vigor was not affected. Seeds of this species were partially tolerant to submersion in water, suggesting that C. lucens is a promising species for direct seeding in riparian forest restoration projects.

Superação de dormência em sementes de três espécies de Ipomoea

O conhecimento do método de superação de dormência mais adequado para cada espécie auxilia na identificação do tipo de dormência, bem como na definição de estratégias de manejo que permitam o controle mais eficaz. As espécies do gênero Ipomoea encontram-se amplamente distribuídas nos estados brasileiros, as mais comumente encontradas em lavouras de soja na região Sudoeste do Paraná são I. purpurea, I. indivisa e I. grandifolia. Assim, neste trabalho, o objetivo foi selecionar métodos eficazes de superação da dormência nas espécies Ipomoea indivisa, I. grandifolia e I. purpurea e determinar como eles influenciam na cinética da germinação das sementes dessas espécies. Os tratamentos utilizados foram água quente, escarificação mecânica, escarificação mecânica + resfriamento, escarificação química e testemunha. Na avaliação do efeito dos tratamentos, determinou-se a porcentagem de germinação, tempo médio, índice de velocidade e frequência relativa de germinação. A escarificação com ácido sulfúrico incrementou a germinação das sementes de I. indivisa e I. purpurea e o índice de velocidade de germinação àquelas de I. purpurea. O tratamento com água quente foi o mais eficiente em promover a germinação das sementes de I. grandifolia, e em reduzir o tempo médio de germinação das sementes de I. grandifolia e I. purpurea, de forma que, nos tratamentos de superação de dormência, há sincronização do processo de germinação.

<b>Effect of seed coat on the seed germination and seedling development of <i>Calophyllum brasiliense</i> Cambess. (Clusiaceae)

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

Temperatura na germinação de sementes de genótipos de pitaya

The optimum temperature for germination of cacti vary with the species. With this work, we aimed to evaluate the seeds germination of pitaya genotypes under different temperatures. The used genotypes were: Hylocereus undatus (PB), H. polyrhizus (PV), Selenicereus megalanthus (PA), H. undatus x H. costaricensis (PH1) and H. costaricensis x H. undatus (PH2). For each genotype we used four replicates of 50 seeds, in a completely randomized design. The sowing was carried out on blotter paper in boxes type Gerbox ®, maintained at temperatures of 15, 20, 25, 30 and 35 oC constant and 15-25, 20-30 and 25-35 oC alternating with photoperiod 12 hours. The test lasted 30 days which were appraised the germination percentage, the germination speed index and the average time of germination. For seeds germination of PB, the result obtained in the temperature of 25 oC didn’t differ of the obtained to 30 and 20-30 oC, however it was superior to the others temperatures. In PV, the result at 25 oC didn’t differ of the obtained to 20 and 30 oC, being superior to the results of the others temperatures. For PA, the best result was obtained to 25 oC. In PH1, the temperatures of 25, 30 and 20-30 oC presented superiors results to the others. For PH2, the result obtained in 15-25oC didn’t differ of the obtained at 25 oC, however it was superior to the others temperatures. The constants temperatures of 25 and 30 °C and alternating 20-30 °C are suitable for germination of H. undatus and for the hybrid H . undatus x H. costaricensis . For H. polyrhizus , constant temperatures of 20, 25 to 30 °C are suitable for seed germination. The constant temperature of 25 °C is the most suitable for the germination of S. megalanthus . For the hybrid H. costaricensis x H. undatus , constant temperature of 25 °C and alternating 15-25°C are suitable for seed germination.