Respostas de cultivares de algodão ao cloreto de mepiquat aplicado via embebição de sementes

Abstract

ResumoAs recomendações de reguladores de crescimento cloreto de mepiquat (CM) geralmente não consideram as diferenças entre cultivares de algodoeiro utilizadas para o cultivo. O trabalho teve como objetivo avaliar o crescimento e o desenvolvimento de cultivares de algodão ante a embebição das sementes com regulador de crescimento cloreto de mepiquat, visando à sua caracterização quanto à resposta ao tratamento. Foram utilizadas as cultivares IPR-120, IAC-24, CD-405, Delta Opal e Fibermax 966, cujas sementes foram embebidas em solução contendo 2,0 g de cloreto de mepiquat para cada 100 mL de água deionizada por 12 horas e cultivadas em vaso, em casa de vegetação. Foram avaliadas: a altura de plantas, a altura da inserção do nó cotiledonar, o diâmetro caulinar, a área foliar e a massa da matéria seca da parte aérea. As cultivares tiveram resultados diferenciados ao tratamento de sementes via embebição com regulador de crescimento, sendo as cultivares Fibermax 966, Delta Opal e CD 405 as mais sensíveis. O tratamento foi eficiente na redução do porte, da inserção do nó cotiledonar, da área foliar e da massa da matéria seca da parte aérea do algodoeiro, além de alterar a partição dos assimilados, comparadas com plantas originadas de sementes sem tratamento.Palavras-chave: Gossypium hirsutum r. latifolium, pix, partição de assimilados, redução de crescimento. Response of cotton cultivars to mepiquat chloride applied by soaking seed AbstractRecommendations for use of the plant growth regulator Mepiquat Chloride (MC) usually do not consider differences among cotton cultivars. The objective of this research was to evaluate the growth and development of cotton cultivars after seed soaking with Mepiquat Chloride. The cultivars used were IPR-120, IAC-24, CD-405, Delta Opal e Fibermax 966, whose seeds were soaked in a solution containing 2.0 g of Mepiquat Chloride diluted in 100 mL of deionized water during 12 hours. Seeds were sown in pots and plants were grown under greenhouse conditions. The parameters evaluated were plant height, height of the cotyledon node insertion, stem diameter, leaf area and shoot dry matter. The cultivars presented differential responses to growth regulator, being cultivars Fibermax 966, Delta Opal and CD 405 the most sensitive. The treatment was effective in reducing the plant height and cotyledon node insertion, leaf area and shoot dry matter. Assimilates partitioning was also affected when comparing control and treated plants.

Water deficit in cotton plant originated from seeds treated with growth regulator

“…In a recent study, Almeida & Rosolem (2012) observed that the application of MC to cotton seeds decreased shoot length, but had no significant effect on dry matter production, root length, shoot:root ratio or leaf area:root length ratio. However, Nagashima et al (2011) concluded that cotton seeds treated with MC decreased shoot dry matter by 62%, while the leaf area decreased 52%.…”