Genes expression and genetic control to cold tolerance during corn seeds germination

• Autor(a) principal: Silva Neta, Izabel Costa
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFLA
• Texto Completo: http://repositorio.ufla.br/jspui/handle/1/28253
• topic: Milho – Sementes – Fisiologia; Milho – Sementes – Qualidade; Milho – Melhoramento genético; Estresse térmico; Corn – Seeds – Physiology; Corn – Seeds – Quality; Corn – Breeding; Thermal stress; Zea mays; Fitotecnia

Increasing plant tolerance to environmental stresses is one of the most important objectives of breeding programs and selection of superior genotypes should take into account the germination and emergence phase of seedlings. Under suitable temperature conditions corn seeds germinate in approximately four days, however as the temperature is reduced, the time required for the germination process increase. The cold tolerance study in corn seeds and seedlings through physiological seed quality assessments, as well as the genetic feature study is associated with this characteristic. It allows an early genotypes characterization with tolerance to this adverse temperature condition. Thus, the objective in this work was to study the genetic control for cold tolerance during the germination process in corn seeds. Six corn lines were used, three classified as tolerant to low germination temperature (91, 64 and 63) and three susceptible to this stress condition (44, 54 and 57). A field was developed to multiply the six lines and concomitant production of hybrid seeds, in a partial diallel scheme including the reciprocal ones. Thus, seeds of 24 corn genotypes were produced. In order to evaluate the physical and physiological quality of corn seeds, the water content was determined and germination tests were carried out at temperatures of 10 and 25 ºC. After obtaining physiological seed quality data for all lines and hybrids considered, they were used to estimate values for heterosis and the estimates of the general and specific combination and reciprocal maternal and non-maternal effects. It was observed that there is heterosis expression for the germination low temperature tolerance characteristic in corn seeds. For the genetic control of germination low temperature tolerance in corn seeds, non-additive effect genes are more important. There is a reciprocal effect for the germination low temperature tolerance characteristic of corn seeds. There is an effect of maternal origin for the parents in the crosses tested, which shows the importance of the choice of the female parents to compose the crosses.