Avaliação do ácido salicílico exógeno e fontes e doses de silício no cultivo in vitro e na aclimatização de orquídeas epífitas
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Data
2020-03-06
Autores
Mantovani, Cibele [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A produção comercial de orquídeas é uma atividade de destaque na floricultura mundial e a cultura de tecidos tem sido a técnica mais utilizada para obtenção de grande quantidade de mudas em curto espaço de tempo. Fontes de silício e o ácido salicílico dependendo da concentração e da espécie cultivada podem induzir a toxicidade, mas não há informações para orquídeas sob cultivo in vitro. Como os efeitos da adição de ácido salicílico e fontes de silício na composição do meio de cultivo in vitro ainda não são totalmente conhecidos estudou-se, separadamente neste trabalho, o efeito do ácido salicílico exógeno e a adição de silício (Si) in vitro e o efeito residual do Si durante a aclimatização. Para isso foram realizados dois experimentos. O experimento 1 consistiu no cultivo in vitro das orquídeas Cymbidium atropurpureo e Phalaenopsis Golden Peoker em meio MS acrescido dos tratamentos com ácido salicílico: 0; 50; 100; 200; 300; 400; 500 e 1000 µmol L-1 de AS durante 210 dias. Já o experimento 2 consistiu no cultivo in vitro das orquídeas Cymbidium atropurpureo e Dendrobium secundum, o meio MS utilizado para propagação das plântulas foi acrescido dos tratamentos constituídos por seis concentrações (0,00; 14,15; 28,30; 42,45 e 56,6 mmol de Si por L) de cada fonte de Si (nanossílica, silicato de potássio com silicato de sódio e ácido monossilícico) e ao término do cultivo in vitro as plântulas foram analisadas. Os resultados indicam que a adição de AS reduziu todas as variáveis de crescimento avaliadas e induziu toxicidade. A adição de silício na forma da mistura de silicato de potássio e silicato de sódio promoveu o máximo crescimento de Dendrobium secundum. A nanossílica foi a fonte mais promissora para o cultivo in vitro de Cymbidium atropurpureo e o ácido monossilícico foi a fonte mais tóxica.
The commercial production of orchids is a prominent activity in world floriculture, and the cultivation of plant tissues has been the most used technique for obtaining large quantities of seedlings in a short time. Sources of silicon and salicylic acid depending on the concentration and species grown can induce toxicity, but there is no information for orchids under in vitro cultivation. As the effects of the addition of salicylic acid and silicon sources on the composition of the in vitro culture medium are not yet fully understood, the effect of exogenous salicylic acid and the addition of silicon (Si) in vitro and the residual effect of Si during acclimatization were separately studied in this work. For this, two experiments were carried out. Experiment 1 consisted of in vitro cultivation of Cymbidium atropurpureo and Phalaenopsis Golden Peoker orchids in MS medium plus treatments with salicylic acid: 0; 50; 100; 200; 300; 400; 500 and 1000 µmol L-1 AS for 210 days. In experiment 2 consisted of in vitro cultivation of Cymbidium atropurpureo and Dendrobium secundum, the MS medium used for seedling propagation was added with treatments consisting of six concentrations (0.00; 14.15; 28.30; 42.45 and 56.6 mmol of Si per L) from each source of Si (nanosilica, potassium silicate with sodium silicate and monosilicic acid) and at the end of cultivation the seedlings were analyzed. The results indicate that the addition of AS reduced all the growth variables evaluated and induced toxicity. The addition of silicon in the form of a mixture of potassium silicate and sodium silicate promoted the maximum growth of Dendrobium secundum. Nanosilica was the most promising source for the in vitro cultivation of Cymbidium atropurpureo and monosilicic acid was the most toxic source.
The commercial production of orchids is a prominent activity in world floriculture, and the cultivation of plant tissues has been the most used technique for obtaining large quantities of seedlings in a short time. Sources of silicon and salicylic acid depending on the concentration and species grown can induce toxicity, but there is no information for orchids under in vitro cultivation. As the effects of the addition of salicylic acid and silicon sources on the composition of the in vitro culture medium are not yet fully understood, the effect of exogenous salicylic acid and the addition of silicon (Si) in vitro and the residual effect of Si during acclimatization were separately studied in this work. For this, two experiments were carried out. Experiment 1 consisted of in vitro cultivation of Cymbidium atropurpureo and Phalaenopsis Golden Peoker orchids in MS medium plus treatments with salicylic acid: 0; 50; 100; 200; 300; 400; 500 and 1000 µmol L-1 AS for 210 days. In experiment 2 consisted of in vitro cultivation of Cymbidium atropurpureo and Dendrobium secundum, the MS medium used for seedling propagation was added with treatments consisting of six concentrations (0.00; 14.15; 28.30; 42.45 and 56.6 mmol of Si per L) from each source of Si (nanosilica, potassium silicate with sodium silicate and monosilicic acid) and at the end of cultivation the seedlings were analyzed. The results indicate that the addition of AS reduced all the growth variables evaluated and induced toxicity. The addition of silicon in the form of a mixture of potassium silicate and sodium silicate promoted the maximum growth of Dendrobium secundum. Nanosilica was the most promising source for the in vitro cultivation of Cymbidium atropurpureo and monosilicic acid was the most toxic source.
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Palavras-chave
Orchidaceae, Silício, Plantas Nutrição, Propagação