Pré-tratamentos com luz em sementes de tomateiro para indução de tolerância ao déficit hídrico
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Data
2016-02-26
Autores
Santos, Joel Cabral dos [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O déficit hídrico está entre as principais restrições para o cultivo de espécies de interesse agrícola, pois este fenômeno ocasiona diminuição no crescimento e produtividade das plantas. O condicionamento fisiológico de sementes surge como uma técnica que pode induzir à tolerância das plantas a diversos estresses abióticos. Desta forma objetivou-se com este trabalho pré-tratar sementes de tomateiro com diferentes qualidades de luz para indução da tolerâncias ao déficit hídrico. Para isto foram realizados três experimentos, nos quais sementes de tomateiro foram embebidas em água destilada sob os comprimentos de onda do vermelho, vermelho extremo, verde e azul por 10 ou 20 horas (experimento I e II, respectivamente) decorrido o tempo de embebição as sementes foram colocadas para secar sob os mesmo comprimento de onda durante 48 horas. No experimento III, sementes também foram colocadas para embeber durante 20 horas, após 10 horas de embebição as sementes foram exposta a luz UV-B ou branca por um período de 0, 1, 2, 3 e 4 horas, seguido de privação da luz. Após o período de embebição, foram postas para secar na ausência da luz por 48 horas. Para as análises de germinação e crescimento, sementes foram colocadas para germinar em caixas tipo gerbox contendo 2 folhas de papel de filtro umedecidas com 20 mL de água ou solução com potencial osmótico de -0,1 MPa, induzido com polietilenoglicol. O baixo potencial osmótico da condição estressora reduziu os valores da maioria das variáveis aqui estudadas. O tratamento com luz vermelha durante 20 horas melhorou o TMG e IVG das sementes de tomateiro. O pré tratamento com luz branca e UV-B durante 0, 1, 2, 3 e 4 horas melhoram a porcentagem de germinação, TMG e IVG da sementes de tomateiro sob déficit hídrico. Com isto, chegou-se a conclusão que o pré-tratamento com luz vermelha durante 20 horas, o pré-tratamento com luz branca, UV-B ou hidrocondicionamento de sementes de tomateiro pode induzir a tolerância ao déficit hídrico.
The water deficit is among the main constraints for the cultivation of species of agricultural interest, because this phenomenon promotes decreases in the growth and productivity of crops. The physiological conditioning of seeds arises as a technic that can induce the plant tolerance to many abiotic stresses. In this context aimed to evaluate in this work pre-treat tomato seeds with different qualities of light to induce the water deficit tolerances. For that, were realized three experiments which tomato seeds were imbibed in distilled water under wavelengths red, extreme red, green and blue for 10 or 20 hours (experiment I and II, respectively). After imbibition period the seeds were put to dry under the same wavelength during 48 hours. In the experiment III, seeds were put to imbibition during 20 hours also, after 10 hours of imbibition the seeds were exposed to UV-B light or white for a period of 0, 1, 2, 3 and 4 hours, followed by light privation. After the imbibition period, were put to dry in the absence of light for 48 hours. For analysis of germination and growth, the seeds were put to germinate in gerbox recipients containing 2 leaves of filter paper moistened with 20 ml of water or solution with osmotic potential of -0,1 MPa, induced by polyethylene glycol. The low osmotic potential of stress condition decreased the values of most of the analyzed variables in this paper. The treatment with red light during 20 hours improved TMG and IVG of tomato seeds. The pre-treatment with white light and UV-B during 0, 1, 2, 3 and 4 hours improved the germination percentage, TMG and IVG of tomato seeds under water deficit. So, we concluded that pre-treatment with red light during 20 hours, the pre-treatment with white light, UV-B or hydropriming of tomato seeds can induce water deficit tolerance.
The water deficit is among the main constraints for the cultivation of species of agricultural interest, because this phenomenon promotes decreases in the growth and productivity of crops. The physiological conditioning of seeds arises as a technic that can induce the plant tolerance to many abiotic stresses. In this context aimed to evaluate in this work pre-treat tomato seeds with different qualities of light to induce the water deficit tolerances. For that, were realized three experiments which tomato seeds were imbibed in distilled water under wavelengths red, extreme red, green and blue for 10 or 20 hours (experiment I and II, respectively). After imbibition period the seeds were put to dry under the same wavelength during 48 hours. In the experiment III, seeds were put to imbibition during 20 hours also, after 10 hours of imbibition the seeds were exposed to UV-B light or white for a period of 0, 1, 2, 3 and 4 hours, followed by light privation. After the imbibition period, were put to dry in the absence of light for 48 hours. For analysis of germination and growth, the seeds were put to germinate in gerbox recipients containing 2 leaves of filter paper moistened with 20 ml of water or solution with osmotic potential of -0,1 MPa, induced by polyethylene glycol. The low osmotic potential of stress condition decreased the values of most of the analyzed variables in this paper. The treatment with red light during 20 hours improved TMG and IVG of tomato seeds. The pre-treatment with white light and UV-B during 0, 1, 2, 3 and 4 hours improved the germination percentage, TMG and IVG of tomato seeds under water deficit. So, we concluded that pre-treatment with red light during 20 hours, the pre-treatment with white light, UV-B or hydropriming of tomato seeds can induce water deficit tolerance.
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Palavras-chave
Embebição, Germinação, Fotorrecptores, Soaking, Pphotoreceptors, Germination, Fitocromos, Solanum lycopersicum L., Phytochormes