Desempenho de cultivares de trigo em condições de estresses térmico e hídrico
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Data
2018-01-23
Autores
Corrêa, Aretha Arcenio Pimentel [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O melhoramento genético de trigo para a região do Cerrado brasileiro visa o desenvolvimento de genótipos adaptados à condições de calor e seca, além de produtivos. Neste sentido, o objetivo do presente estudo foi avaliar a tolerância de cultivares de trigo submetidas aos estresses térmico e hídrico, por meio da avaliação de caracteres relevantes para o melhoramento da cultura, bem como estudar a relação entre eles. Para tanto, 30 cultivares de trigo foram submetidas à quatro condições em casa de vegetação: Controle, Seca, Seca+Calor, e Calor, aplicando os estresses do período do emborrachamento até o final da antese, por meio da suspensão da irrigação e da exposição à temperaturas elevadas. Foram avaliados os caracteres: dias para o emborrachamento, dias para o espigamento, dias para a antese, ciclo, altura da planta, nº de espigas por planta, peso médio de espigas, peso de grãos por espiga, tamanho médio de espigas, nº de espiguetas por espiga, nº de grãos por espiga e porcentagem de espiguetas férteis. Foram realizadas análises de variância individuais e conjunta, análise de correlações genéticas e fenotípicas, análise de componentes principais e análise de agrupamento pelos métodos de Ward e “K-means”. Os resultados da análise de variância conjunta entre os ambientes Controle, Seca e Calor indicaram a existência de interação genótipo x ambiente para as características ciclo, nº de espigas por planta, peso médio de espigas, peso de grãos por espiga, tamanho médio de espigas, nº de espiguetas por espiga, nº de grãos por espiga e porcentagem de espiguetas férteis. As correlações entre os caracteres de produção foram afetadas no ambiente Seca, quando comparadas às correlações obtidas nos ambientes Controle e Calor. O caráter nº de espigas por planta apresentou correlação negativa com os outros caracteres de produção em todos os ambientes. A fertilidade das espiguetas foi mais afetada no ambiente Seca. Nas análises de componentes principais, três autovalores explicaram uma variância superior a 80% em todos os ambientes. Na análise de componentes principais envolvendo os três ambientes simultaneamente, os componentes de produção ficaram retidos no primeiro componente, seguido por peso de grãos e porcentagem de espiguetas férteis no segundo componente, enquanto ciclo e altura ficaram retidos somente no terceiro. As análises de agrupamento formaram cinco grupos para os ambientes Controle e Calor e sete grupos para o ambiente Seca. Observou-se ainda que, em situação de estresse térmico, as cultivares mais produtivas foram IPR Catuara TM, BRS Gralha Azul, Anahuac 75 e IPR 144. Sob deficiência hídrica, destacaram-se Embrapa 21, Quartzo, BRS 208. As cultivares com menor adaptação às condições de estresse de modo geral, foram BRS 229, BRS 327 e Topázio.
Wheat breeding for brazilian Cerrado region aims the development of productive genotypes adapted to heat and drought. In this sense, the objective of the present study was to evaluate the tolerance of wheat cultivars subjected to heat and drought stresses, as well as to study the relationships between traits that are relevant to wheat breeding. Therefore, 30 cultivars were conducted in four different greenhouse environments, namely: Control, Drought, Drought + Heat, and Heat, applying the stresses in the period of booting until final anthesis, by suspending the irrigation and exposing to high temperatures. Were evaluated the number of days to booting, number of days to heading, number of days to anthesis, cycle, plant height, number of spikes per plant, mean spike weight, mean grain weight, mean spike size, number of spikelets per spike, number of grains per spike and percentage of fertile spikelets. Was performed individual and joint analysis of variance, genotypic and phenotypic correlations analysis, principal component analysis and cluster analysis by Ward's and “K-means” methods. The results of the joint variance analysis between the Control, Drought, and Heat environments indicated the existence of genotype x environment interactions for the variables cycle, number of spikes per plant, mean spike weight, mean grain weight, mean spike size, number of spikelets per spike, number of grains per spike and percentage of fertile spikelets. The correlations between the production characters were affected in the drought stress environment when compared to Control and Heat environments. The variable number of spikes per plant showed a negative correlation with the other production characters in all environments. Drought stress affected the fertility of the spikelets. In the principal components analysis, three eigenvalues explained a variance greater than 80% in all environments. In the principal components analysis involving the three environments simultaneously, the yield traits were retained in the first component, followed by grain weight and percentage of fertile spikelets in the second component, while cycle and plant height were retained only in the third. The cluster analyzes formed five groups for the Control and Heat environments and seven groups for the Drought environment. It was also observed that, in the event of heat stress, the most productive cultivars were IPR Catuara TM, BRS Gralha Azul, Anahuac 75 and IPR 144. Under water deficiency, Embrapa 21, Quartzo and BRS 208 stood out. The cultivars that showed less adaptation under stress conditions were BRS 229, BRS 327 and Topázio.
Wheat breeding for brazilian Cerrado region aims the development of productive genotypes adapted to heat and drought. In this sense, the objective of the present study was to evaluate the tolerance of wheat cultivars subjected to heat and drought stresses, as well as to study the relationships between traits that are relevant to wheat breeding. Therefore, 30 cultivars were conducted in four different greenhouse environments, namely: Control, Drought, Drought + Heat, and Heat, applying the stresses in the period of booting until final anthesis, by suspending the irrigation and exposing to high temperatures. Were evaluated the number of days to booting, number of days to heading, number of days to anthesis, cycle, plant height, number of spikes per plant, mean spike weight, mean grain weight, mean spike size, number of spikelets per spike, number of grains per spike and percentage of fertile spikelets. Was performed individual and joint analysis of variance, genotypic and phenotypic correlations analysis, principal component analysis and cluster analysis by Ward's and “K-means” methods. The results of the joint variance analysis between the Control, Drought, and Heat environments indicated the existence of genotype x environment interactions for the variables cycle, number of spikes per plant, mean spike weight, mean grain weight, mean spike size, number of spikelets per spike, number of grains per spike and percentage of fertile spikelets. The correlations between the production characters were affected in the drought stress environment when compared to Control and Heat environments. The variable number of spikes per plant showed a negative correlation with the other production characters in all environments. Drought stress affected the fertility of the spikelets. In the principal components analysis, three eigenvalues explained a variance greater than 80% in all environments. In the principal components analysis involving the three environments simultaneously, the yield traits were retained in the first component, followed by grain weight and percentage of fertile spikelets in the second component, while cycle and plant height were retained only in the third. The cluster analyzes formed five groups for the Control and Heat environments and seven groups for the Drought environment. It was also observed that, in the event of heat stress, the most productive cultivars were IPR Catuara TM, BRS Gralha Azul, Anahuac 75 and IPR 144. Under water deficiency, Embrapa 21, Quartzo and BRS 208 stood out. The cultivars that showed less adaptation under stress conditions were BRS 229, BRS 327 and Topázio.
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Palavras-chave
Triticum aestivum, calor, seca, Cerrado, Interação genótipo x ambiente, thermal stress, water stress, genotype x environment interactions