Citocinina na cultura do arroz de terras altas
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Data
2019-08-12
Autores
Alves, Cleiton José
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Universidade Estadual Paulista (Unesp)
Resumo
A aplicação da citocinina thidiazuron (TDZ) é uma técnica que promove aumentos na produtividade de arroz (Oryza sativa L.), no entanto, é necessário entender o funcionamento dessa substância em plantas de arroz. Objetivou-se com esse trabalho verificar a influência do TDZ nos aspectos fisiológicos, morfológicos, nutricionais e produtivos de um cultivar de arroz de terras altas. Foi realizado experimento com delineamento em blocos casualizados, aplicando doses de thidiazuron (0, 0,8, 1,6 e 2,4 g ha-1) no perfilhamento do cultivar Ana 8001, favorecido com irrigação por aspersão, durante duas safras (2015/2016 e 2016/2017). Foi avaliado o teor foliar das citocininas 6-benzilaminopurina (BAP) e trans-zeatina ribosídeo (TZR), absorção de N, P, K, Ca, Mg, S, Fe, Cu, Zn e Mn, crescimento da planta, componentes da produção e produtividade de grãos. Realizou-se também experimento em casa de vegetação com o objetivo de verificar a influência de citocininas na altura, componentes da produção, produtividade de grãos e expressão genica de cultivares mutantes de arroz, alterados na rota de sinalização celular desse hormônio. A aplicação de citocinina aumentou os teores foliares de 6-benzilaminopurina e trans-zeatina ribosídeo na primeira safra. O aumento no número de espiguetas por panícula e fertilidade das espiguetas, em função das doses de TDZ, resultaram em incrementos na produtividade na ordem de 24% e 13% na safra 2015/2016 e 2016/2017, respectivamente. Em 2016/2017, os teores de K na folha aumentaram 2,0, 6,8, 3,1 e 0,9 g kg-1 com a aplicação das doses de TDZ na diferenciação foliar, florescimento, grão leitoso e ponto de colheita, respectivamente. A concentração de K na panícula aumentou 1,91 g kg-1 no ponto de colheita. Apesar das diferenças climáticas entre as duas safras, foi possível observar que com a aplicação de TDZ houve maior acúmulo de matéria seca nas folhas e colmo da planta, sendo posteriormente translocada para as estruturas reprodutivas. Nos cultivares mutantes de arroz OsPHP, OsRR tipo B e OsCKX, houve diferenças nos pigmentos fotossintéticos, altura de plantas, componentes da produção e produtividade de grãos em resposta a aplicação de citocinina. A expressão genica mostra que, mesmo com rupturas no OsHK, a planta aumenta a expressão de OsRR4, gene que governa as características relacionadas à citocinina na planta. O uso de citocinina na cultura do arroz promove maior absorção de nutrientes, crescimento e desenvolvimento da planta, resultando em maior produtividade de grãos.
Application of the cytokinin thidiazuron (TDZ) is a technique which promotes increases in grain yield of rice (Oryza sativa L.), however, it is necessary to understand the action of this substance in rice plants. The objective of this work was to verify the influence of TDZ on the physiological, morphological, nutritional and productive aspects of an upland rice cultivar. A randomized block design experiment was carried out, applying doses of thidiazuron (0, 0.8, 1.6 and 2.4 g ha-1) on tillering stage of the cultivar ANa 8001, favored by sprinkler irrigation, during two crop seasons (2015/2016 and 2016/2017). It was evaluated the leaf content of cytokines 6-benzylaminopurine (BAP) and trans-zeatin riboside (TZR), the uptake of N, P, K, Ca, Mg, S, Fe, Cu, Zn and Mn, plant growing and grain yield. An experiment was also carried out to verify the influence of cytokinins on morphological aspects and genetic expression of mutant rice cultivars, altered in the cellular pathway signaling of this hormone. The application of cytokinin increased leaf contents of 6-benzylaminopurine and trans-zeatin riboside in the first crop season. The increase in the number of spikilets per panicle and spikelet fertility as a function of TDZ doses resulted in increases of 24% and 13% in 2015/2016 and 2016/2017, respectively. In 2016/2017, the leaf K contents increased by 2.0, 6.8, 3.1 and 0.9 g kg-1 with the application of TDZ doses on leaf differentiation, flowering, milky grain and harvest point. respectively. Panicle K content increased 1.91 g kg-1 at harvest point. Despite the climatic differences between the two-crop season, it was possible to observe that cytokinin increases the dry matter accumulation in the leaves and stalk of the plant, being after translocated to the reproductive structures, resulting in increases of grain yield. The OsPHP, OsRR type B and OsCKX rice mutant cultivars showed increases in photosynthetic pigments, differences in plant height, yield components and grain yield in response to cytokinin doses. The gene expression shows that, even with OsHK disruption, the plant increases the expression of OsRR4, the gene that governs cytokinin-related characteristics in the plant. The use of cytokinin in rice crop promotes greater nutrient uptake, plant growth and development, resulting in higher grain yield.
Application of the cytokinin thidiazuron (TDZ) is a technique which promotes increases in grain yield of rice (Oryza sativa L.), however, it is necessary to understand the action of this substance in rice plants. The objective of this work was to verify the influence of TDZ on the physiological, morphological, nutritional and productive aspects of an upland rice cultivar. A randomized block design experiment was carried out, applying doses of thidiazuron (0, 0.8, 1.6 and 2.4 g ha-1) on tillering stage of the cultivar ANa 8001, favored by sprinkler irrigation, during two crop seasons (2015/2016 and 2016/2017). It was evaluated the leaf content of cytokines 6-benzylaminopurine (BAP) and trans-zeatin riboside (TZR), the uptake of N, P, K, Ca, Mg, S, Fe, Cu, Zn and Mn, plant growing and grain yield. An experiment was also carried out to verify the influence of cytokinins on morphological aspects and genetic expression of mutant rice cultivars, altered in the cellular pathway signaling of this hormone. The application of cytokinin increased leaf contents of 6-benzylaminopurine and trans-zeatin riboside in the first crop season. The increase in the number of spikilets per panicle and spikelet fertility as a function of TDZ doses resulted in increases of 24% and 13% in 2015/2016 and 2016/2017, respectively. In 2016/2017, the leaf K contents increased by 2.0, 6.8, 3.1 and 0.9 g kg-1 with the application of TDZ doses on leaf differentiation, flowering, milky grain and harvest point. respectively. Panicle K content increased 1.91 g kg-1 at harvest point. Despite the climatic differences between the two-crop season, it was possible to observe that cytokinin increases the dry matter accumulation in the leaves and stalk of the plant, being after translocated to the reproductive structures, resulting in increases of grain yield. The OsPHP, OsRR type B and OsCKX rice mutant cultivars showed increases in photosynthetic pigments, differences in plant height, yield components and grain yield in response to cytokinin doses. The gene expression shows that, even with OsHK disruption, the plant increases the expression of OsRR4, the gene that governs cytokinin-related characteristics in the plant. The use of cytokinin in rice crop promotes greater nutrient uptake, plant growth and development, resulting in higher grain yield.
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Palavras-chave
Fisiologia vegetal, Regulador vegetal, Análise de crescimento, Absorção de nutrientes, Expressão genica