Breeding, physical and chemical features of maize inbred lines and hybrids with significant breeding traits and efficient photosynthetic functions

Four maize inbred lines with erect top leaves and significant breeding traits, ZPPL 16, ZPPL 218, ZPPL 62 and ZPPL 233, were studied. These inbreds, as a female or a male component, are included into the development of more than 50 maize hybrids. However, only the following four hybrids are widely grown: ZP 341, ZP 434, ZP 578 and ZP 684 and they were also observed. This study confirms our hypothesis that there are elite maize inbred lines and hybrids with top erect leaves that have a dominant trait of an efficient photosynthetic model. The stated maize inbred lines with significant breeding traits are successfully used in contemporary breeding programmes and the production of hybrid seed of high quality. This observation is supported by results obtained on erect leaves of maize inbred lines with significant breeding traits, dynamics of grain dry down during the maturation period and photosynthetic and fluorescenece parameters: changes in the chlorophyll delayed fluorescence intensity during its course and dynamics, the Arrhenius plot for determination of critical temperatures (phase transition temperatures) and the activation energies, as a measure of conformational changes in the thylakoid membrane. Furthermore, a grain structure of observed maize hybrids, including its physical and chemical parameters, were studied. The presented results indicate that properties of maize inbreds and hybrids with significant breeding traits are based on nature of structural and functional changes that occur in their chloroplasts and thylakoid membranes, as well as, other chemical tissue structures of intact leaves and grain, but also on progressive effects in the process of breeding and the production of commercial maize.