Caracterização fisiológica, bioquímica e anatômica em genótipos de algodoeiro herbáceo (gossypium hirsutum l.var. latifolium hutch) em função da aplicação de cloreto de mepiquat
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Data
2016-02-17
Autores
Paixão, Amanda Pereira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os genótipos de algodoeiro herbáceo FMT 701 e Fibermax 966 apresentam características morfofisiológicas distintas devido à sua constituição genética diferenciada, sendo assim, é possível que possuam diferenças na atividade de enzimas do complexo antioxidante (superóxido dismutase, catalase e peroxidase), bem como nos principais parâmetros fotossintéticos e anatômicos foliares, em função da aplicação de doses crescentes do regulador de crescimento, cloreto de mepiquat (CM). O objetivo deste trabalho foi avaliar dois genótipos de algodoeiro, com características genéticas distintas, em função da aplicação de doses crescentes de CM, através de análises fisiológicas e bioquímicas, bem como a anatomia, biometria e a constituição histoquímica do limbo foliar. Foram realizados dois experimentos. O 1° experimento foi realizado em condições de campo, na região de Cerrado, cujo delineamento experimental adotado foi o de blocos ao acaso, em esquema fatorial 5x2 totalizando 10 tratamentos, com 4 repetições, perfazendo um total de 40 parcelas. O CM foi aplicado via foliar, parcelado em três aplicações realizadas aos 50, 60 e 70 dias após a emergência (DAE), cujos tratamentos foram constituídos pela aplicação de quatro doses de CM (500; 1,000; 1,500; e 2,500 mL ha-1 ) e uma testemunha. O 2° experimento foi realizado em casa de vegetação, onde utilizou-se as mesmas doses de CM e o mesmo delineamento utilizado no 1° experimento, totalizando-se 40 vasos. O experimento de campo foi conduzido até o final do ciclo, aos 136 DAE, visando avaliar também os componentes de produtividade. O experimento da casa de vegetação foi conduzido até os 94 DAE. Os resultados obtidos dos genótipos FMT 701 e Fibermax 966 cultivados no campo e em casa de vegetação sugerem que o CM é responsivo na redução de crescimento em altura, diâmetro, número de nós, comprimento do quinto ramo, ramos reprodutivos, área foliar e massa seca. A qualidade de fibras avaliado no experimento de campo evidenciou que as doses de CM aumentaram o comprimento de fibra, a resistência e o índice de consistência de fiação, e reduziu o índice de fibras curtas, porém não influenciou os componentes de produção. Tanto no campo quanto em casa de vegetação, as doses de CM influenciaram os parâmetros fotossintéticos, porém de forma diferenciada. A análise anatômica e histoquímica foliar realizada no experimento de campo evidenciou que as doses de CM influenciaram de forma distinta às espessuras da epiderme adaxial e abaxial, parênquima paliçádico e lacunoso e a espessura total da região internervural e da região próxima a nervura central. O número de estômatos adaxial foi reduzido em função das doses de CM em ambos genótipos. A análise histoquímica demonstrou que os genótipos de algodoeiro apresentam uma distribuição diferenciada de substâncias pécticas, lipídeos, amido e compostos fenólicos em suas folhas e o CM influenciou nessa distribuição. No experimento de campo, a enzima peroxidase (POD) aumentou sua atividade em função das doses de CM nos genótipos, desintoxicando as células dos radicais livres formados, e em casa de vegetação o CM não alterou a atividade das enzimas antioxidantes, sugerindo ausência de estresse oxidativo nos dois experimentos.
The upland cotton genotypes FMT 701 and Fibermax 966 have distinct morphophysiological characteristics due to their different genetic constitution, and thus, it is possible to have differences in the activity of the antioxidant complex enzymes (superoxide dismutase, catalase and peroxidase) as well as the main parameters photosynthesis and leaf anatomical, depending on the application of increasing doses of growth regulator, mepiquat chloride (MC). The objective of this study was to evaluate two cotton genotypes with different genetic characteristics, depending on the application of increasing doses of MC through physiological and biochemical analysis, as well as anatomy, biometrics and immunohistochemistry constitution of the leaf blade. Two experiments were performed. The 1st experiment was conducted under field conditions in the Cerrado region, whose experimental design was a randomized block design in a 5x2 factorial scheme totaling 10 treatments with 4 repetitions, totaling 40 parcells. The MC was applied via foliar installments in three applications performed at 50, 60 and 70 days after emergence (DAE), the treatments were a combination of four doses of MC (500; 1,000; 1,500; and 2,500 ml ha-1 ) and a witness. The 2nd experiment was conducted in a greenhouse, where we used the same doses of MC and the same design used in experiment 1, amounting to 40 vessels. The field experiment was conducted until the end of the cycle to 136 DAE, aimed also evaluate the productivity components. The experiment in greenhouse was conducted until 94 DAE. The results of the FMT 701 genotypes and Fibermax 966 grown in field and greenhouse suggest that the MC is responsive in growth reduction in height, diameter, number of nodes, the fifth branch length, reproductive branches, leaf area and dry mass. The quality of fibers evaluated in the field experiment showed that the MC doses increased the fiber length, strength and the spinning consistency index, and reduced the rate of short fibers, but did not affect the production of components. Both in the field and in the greenhouse, the MC levels influenced the photosynthetic parameters, but in different ways. Leaf anatomical and immunohistochemical analysis in the field experiment showed that the MC levels influenced differently to the thickness of adaxial and abaxial epidermis, palisade and spongy parenchyma and total thickness internerval region and the region near the midrib. The number of adaxial stomata was reduced according to the MC doses in both genotypes. The immunohistochemical analysis showed that the cotton genotypes have a different distribution of pectic substances, lipids, starch and phenolic compounds in their leaves and the MC influence this distribution. In the field experiment, the enzyme peroxidase (POD) increased its activity on the basis of MC doses in genotypes, detoxifying cells from free radicals formed, and in a greenhouse the MC did not alter the activity of antioxidant enzymes, suggesting the absence of stress oxidative in both experiments.
The upland cotton genotypes FMT 701 and Fibermax 966 have distinct morphophysiological characteristics due to their different genetic constitution, and thus, it is possible to have differences in the activity of the antioxidant complex enzymes (superoxide dismutase, catalase and peroxidase) as well as the main parameters photosynthesis and leaf anatomical, depending on the application of increasing doses of growth regulator, mepiquat chloride (MC). The objective of this study was to evaluate two cotton genotypes with different genetic characteristics, depending on the application of increasing doses of MC through physiological and biochemical analysis, as well as anatomy, biometrics and immunohistochemistry constitution of the leaf blade. Two experiments were performed. The 1st experiment was conducted under field conditions in the Cerrado region, whose experimental design was a randomized block design in a 5x2 factorial scheme totaling 10 treatments with 4 repetitions, totaling 40 parcells. The MC was applied via foliar installments in three applications performed at 50, 60 and 70 days after emergence (DAE), the treatments were a combination of four doses of MC (500; 1,000; 1,500; and 2,500 ml ha-1 ) and a witness. The 2nd experiment was conducted in a greenhouse, where we used the same doses of MC and the same design used in experiment 1, amounting to 40 vessels. The field experiment was conducted until the end of the cycle to 136 DAE, aimed also evaluate the productivity components. The experiment in greenhouse was conducted until 94 DAE. The results of the FMT 701 genotypes and Fibermax 966 grown in field and greenhouse suggest that the MC is responsive in growth reduction in height, diameter, number of nodes, the fifth branch length, reproductive branches, leaf area and dry mass. The quality of fibers evaluated in the field experiment showed that the MC doses increased the fiber length, strength and the spinning consistency index, and reduced the rate of short fibers, but did not affect the production of components. Both in the field and in the greenhouse, the MC levels influenced the photosynthetic parameters, but in different ways. Leaf anatomical and immunohistochemical analysis in the field experiment showed that the MC levels influenced differently to the thickness of adaxial and abaxial epidermis, palisade and spongy parenchyma and total thickness internerval region and the region near the midrib. The number of adaxial stomata was reduced according to the MC doses in both genotypes. The immunohistochemical analysis showed that the cotton genotypes have a different distribution of pectic substances, lipids, starch and phenolic compounds in their leaves and the MC influence this distribution. In the field experiment, the enzyme peroxidase (POD) increased its activity on the basis of MC doses in genotypes, detoxifying cells from free radicals formed, and in a greenhouse the MC did not alter the activity of antioxidant enzymes, suggesting the absence of stress oxidative in both experiments.
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Palavras-chave
Regulador de crescimento, Características agronômicas, Enzimas antioxidantes, Estresse oxidativo, Aparato fotossintético, Growth regulator, Agronomic characteristics, Antioxidant enzymes, Oxidative stress, Photosynthetic apparatus