Influência de fatores do ambiente na germinação de sementes de grama-tapete (Axonopus affinis Chase)
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Data
2016-07-28
Autores
Pereira, Suzana Targanski Sajovic [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste trabalho foi verificar a influência da temperatura, da luz, do substrato, das formas de semeadura, do estresse salino e hídrico na germinação da gramínea Axonopus affinis. Foram quatro experimentos, todos conduzidos em câmara de germinação, onde as condições de temperatura, umidade e fotoperíodo foram controladas; o delineamento experimental utilizado foi inteiramente casualizado e utilizou-se 100 sementes por parcela. Para o estudo da temperatura e da luz (experimento 1), os tratamentos foram arranjados em esquema fatorial 6 x 2, composto de seis condições de temperatura (constante de 20, 25, 30 e 35 ºC e alternadas de 20-30 ºC e 20-35 ºC) e duas condições de luminosidade (―claro‖: 8 horas de luz e 16 horas de escuro e ―escuro‖: 24 h na ausência de luz) e quatro repetições. Para o estudo de substrato e forma de semeadura (experimento 2) foram quatro tratamentos (sobre papel, entre papel, sobre areia e entre areia) e cinco repetições. Para o estudo do estresse salino (experimento 3) foram cinco tratamentos (concentrações de NaCl: 0, 25, 50, 75 e 100 mM) e quatro repetições. Para o estudo do estresse hídrico e formas de semeadura (experimento 4), os tratamentos foram distribuídos em esquema fatorial 3 x 2 onde foram testados três níveis de capacidade de retenção de água (50, 75 e 100%) e duas formas de semeadura (sobre areia e entre areia) e quatro repetições. Avaliou-se porcentagem de germinação e Índice de Velocidade de Germinação. Concluiu-se que a germinação de sementes foi mais efetiva em temperaturas alternadas de 20-30 ºC e 20-35 ºC sob condição de luz e nos substratos sobre papel, entre papel e sobre areia; a concentração de NaCl não afetou a porcentagem de germinação, porém, o aumento da concentração diminuiu gradativamente a velocidade de germinação; maior porcentagem e velocidade de germinação ocorreu quando as sementes foram colocadas sobre areia, mantida com 100% da capacidade de retenção de água.
This work aim was verify the temperature, light, substrate, ways of sowing, and salt and hydric stress influence into the Axonopus affinis germination. All the four trials were carried out in a germination chamber under temperature, humidity, and photoperiod controlled conditions. The experimental design used was the completely randomized one, with 100 seeds in each plot. To study the temperature and light (experiment 1), the trials were arranged in a factorial scheme 6x2, with six temperature conditions (constant temperatures of 20, 25, 30 and 35 °C and alternate temperatures of 20-30 °C and 20-25 °C) and two lightning conditions (light: 8 hours of light and 16 hours of dark and "dark": 24 h in the dark) and four replications. To the substrate and sowing trial (experiment 2) we used four treatments (on paper, between paper, on sand, and between sand) with five replications. To the salt stress trial (experiment 3) we used five treatments (NaCl concentrations: 0, 25, 50, 75, and 100 mM) with four replications. To the hydric stress trial the treatments were arranged in a 3x2 factorial scheme (experiment 4) where we tested three levels of water retention capacity (50, 75, and 100%) and two ways of sowing (on sand and between sand) and four replications. We evaluated the germination percentage and Germination Time Index. We could conclude that the seed germination was more effective when the temperature was alternated of 20-30 °C and 20-35 °C, under light condition, and on a paper substrate, between papers and on the sand. The NaCl concentration did not affect the germination percentage. However, the higher was the NaCl concentration, the slower was the germination. A faster and higher germination occurred when seeds were on the sand kept at 100% of water retention capacity.
This work aim was verify the temperature, light, substrate, ways of sowing, and salt and hydric stress influence into the Axonopus affinis germination. All the four trials were carried out in a germination chamber under temperature, humidity, and photoperiod controlled conditions. The experimental design used was the completely randomized one, with 100 seeds in each plot. To study the temperature and light (experiment 1), the trials were arranged in a factorial scheme 6x2, with six temperature conditions (constant temperatures of 20, 25, 30 and 35 °C and alternate temperatures of 20-30 °C and 20-25 °C) and two lightning conditions (light: 8 hours of light and 16 hours of dark and "dark": 24 h in the dark) and four replications. To the substrate and sowing trial (experiment 2) we used four treatments (on paper, between paper, on sand, and between sand) with five replications. To the salt stress trial (experiment 3) we used five treatments (NaCl concentrations: 0, 25, 50, 75, and 100 mM) with four replications. To the hydric stress trial the treatments were arranged in a 3x2 factorial scheme (experiment 4) where we tested three levels of water retention capacity (50, 75, and 100%) and two ways of sowing (on sand and between sand) and four replications. We evaluated the germination percentage and Germination Time Index. We could conclude that the seed germination was more effective when the temperature was alternated of 20-30 °C and 20-35 °C, under light condition, and on a paper substrate, between papers and on the sand. The NaCl concentration did not affect the germination percentage. However, the higher was the NaCl concentration, the slower was the germination. A faster and higher germination occurred when seeds were on the sand kept at 100% of water retention capacity.
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Palavras-chave
Axonopus affinis, Temperatura, Luz, Substrato, Estresse salino, Estresse hídrico, Temperature, Light, Substrate, Salt stress, Water stress