Potencial de cafeeiros híbridos de Timor para tolerância à deficiência hídrica
Arquivos
Data
2023-07-20
Autores
Miranda, Felipe Rodrigues
Título da Revista
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Editor
Universidade Federal de Viçosa
Resumo
As mudanças climáticas globais causam incertezas para a agricultura atual. As previsões apontam que secas, o principal estresse a prejudicar as plantas, se tornarão cada vez mais presentes e impactantes. Isso causa preocupações quanto ao futuro de culturas de extrema importância socioeconômica no Brasil, como o café. Nesse cenário, abordagens que favoreçam a produção mesmo em condições de restrição hídrica ganham um destaque ainda maior, dentre elas, o melhoramento genético. Trabalhos recentes verificaram genes relacionados à resistência a doenças serem coexpressos em cafeeiros tolerantes à seca. Em decorrência de tais observações se suscitou o presente trabalho. Quatro genótipos de cafeeiro (Catiguá MG2 e três genótipos de Híbridos de Timor) foram submetidos ao déficit hídrico, imposto de forma lenta, para avaliar características fisiológicas e verificar se existe uma diferença genotípica de tolerância à seca. O status hídrico das plantas sob seca, avaliado pelo potencial hídrico de antemanhã, foi essencialmente similar entre os genótipos testados. De forma geral, impactos nas trocas gasosas foram observados em todos os genótipos após a imposição da deficiência hídrica, como decréscimos na taxa fotossintética líquida em paralelo a reduções na condutância estomática. Sugere-se que as reduções na performance fotossintética estiveram associadas a limitações estomáticas e não-estomáticas à fotossíntese. As plantas sob seca responderam, ainda, via aumentos na temperatura da copa e reduções na transpiração da planta inteira. Foi observado ajustamento osmótico nos genótipos H.T. 376-31 e H.T. 408-11, em condições de seca. Além da mudança ativa em seu potencial osmótico, o genótipo H.T. 376-31, juntamente com o Catiguá MG2, exibiu reduções no módulo global de elasticidade e aumentos na capacitância foliar. De modo geral, houve aumento na expressão do sistema antioxidante enzimático de todos os genótipos, e apenas no genótipo H.T. 408-11 houve danos oxidativos, a julgar-se pelas maiores concentrações de peróxido de hidrogênio e aldeído malônico. À luz dos dados apresentados e nas presentes condições experimentais, não houve diferenças claras entre os genótipos testados no que respeita à tolerância diferencial à seca. Palavras-chave: Coffea sp.. Fotossíntese. Restrição hídrica. Tolerância à seca.
Global climate change causes uncertainties for current agriculture. Forecasts indicate that droughts, the main stress that harms plants, will become increasingly frequent and impactful. This raises concerns about the future of crops of marked socioeconomic importance in Brazil, such as coffee. In this scenario, approaches that favor production even in conditions of water restriction are of paramount prominence, among them, genetic breeding. Recent work has reported genes related to disease resistance to be co-expressed in drought tolerant coffee plants. As a result of such observations, the present work was planned. Four genotypes of coffee plants (Catiguá MG2 and three genotypes of Timor Hybrids) were submitted to a slowly imposed water deficit to evaluate physiological characteristics and to verify if there is a genotypic difference regarding drought tolerance. The plant water status under drought, as assessed by predawn water potential, was essentially similar among genotypes. In general, impacts on gas exchange were observed in all genotypes upon imposing water deficit, such as decreases in net photosynthetic rate in parallel with reductions in stomatal conductance. Decreases in photosynthetic performance were associated with stomatal and non-stomatal limitations to photosynthesis. Plants further responded to drought stress via increases in canopy temperature and reductions in whole-plant transpiration. Osmotic adjustment was observed in H.T. 376-31 and H.T. 408-11 hybrids under drought conditions. In addition to the active changes in its osmotic potential, the H.T. 376-31 hybrid, together with Catiguá MG2, exhibited reductions in the global modulus of elasticity and increases in leaf capacitance. In general, there was an increased expression of the enzymatic antioxidant system in all genotypes, and oxidative damage was only observed in the H.T. 408-11 hybrid, as judged by the higher concentrations of hydrogen peroxide and malonic dialdehyde. In light of the data presented and under the present experimental conditions, there were no clear differences between the tested genotypes with regard to differential tolerance to drought. Keywords: Coffea sp.. Drought tolerance. Photosynthesis. Water restriction.
Global climate change causes uncertainties for current agriculture. Forecasts indicate that droughts, the main stress that harms plants, will become increasingly frequent and impactful. This raises concerns about the future of crops of marked socioeconomic importance in Brazil, such as coffee. In this scenario, approaches that favor production even in conditions of water restriction are of paramount prominence, among them, genetic breeding. Recent work has reported genes related to disease resistance to be co-expressed in drought tolerant coffee plants. As a result of such observations, the present work was planned. Four genotypes of coffee plants (Catiguá MG2 and three genotypes of Timor Hybrids) were submitted to a slowly imposed water deficit to evaluate physiological characteristics and to verify if there is a genotypic difference regarding drought tolerance. The plant water status under drought, as assessed by predawn water potential, was essentially similar among genotypes. In general, impacts on gas exchange were observed in all genotypes upon imposing water deficit, such as decreases in net photosynthetic rate in parallel with reductions in stomatal conductance. Decreases in photosynthetic performance were associated with stomatal and non-stomatal limitations to photosynthesis. Plants further responded to drought stress via increases in canopy temperature and reductions in whole-plant transpiration. Osmotic adjustment was observed in H.T. 376-31 and H.T. 408-11 hybrids under drought conditions. In addition to the active changes in its osmotic potential, the H.T. 376-31 hybrid, together with Catiguá MG2, exhibited reductions in the global modulus of elasticity and increases in leaf capacitance. In general, there was an increased expression of the enzymatic antioxidant system in all genotypes, and oxidative damage was only observed in the H.T. 408-11 hybrid, as judged by the higher concentrations of hydrogen peroxide and malonic dialdehyde. In light of the data presented and under the present experimental conditions, there were no clear differences between the tested genotypes with regard to differential tolerance to drought. Keywords: Coffea sp.. Drought tolerance. Photosynthesis. Water restriction.
Descrição
Dissertação de mestrado defendida na Universidade Federal de Viçosa.
Palavras-chave
Café - Resistência à seca, Café - Melhoramento genético
Citação
MIRANDA, Felipe Rodrigues. Potencial de cafeeiros híbridos de Timor para tolerância à deficiência hídrica. 2023. 32 f. Dissertação (Mestrado em Fisiologia Vegetal) - Universidade Federal de Viçosa, Viçosa-MG. 2023.