Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Thomas Lübberstedt


The maize (Zea mays L.) in vivo maternal doubled haploid system has been widely applied to maize breeding and genetics in recent decades and is an important part of the majority of public and private maize breeding programs today. The principal advantage of the doubled haploid system is the ability to generate completely homozygous inbred lines in as little as two seasons. Other advantages to this system include more rapid integration of loci of interest and increased usefulness over traditional lines developed through self-pollination. In this dissertation, some of the major problems in the maternal doubled haploid system are addressed. Namely, improvement of maternal inducers, improved understanding of the genetics controlling inducibility, development of an automated system to sort haploid kernels, investigation and application of spontaneous chromosome doubling, and a proposal for the acceleration of the breeding cycle beyond doubled haploids through the in vitro nursery. This dissertation provides some new insight into these problems, as follows. The development and release of a new improved maternal haploid inducer for use in doubled haploid programs. Improved understanding of the quantitative nature of inducibility and the effects of misclassification are discussed. Successful automated discrimination of haploid and diploid kernels using optical and fluorescence methods is described. In an effort to make the doubled haploid system more efficient and safe, a bypass of the colchicine doubling step is proposed through the application and investigation of spontaneous chromosome doubling in haploid plants. Finally, as a proposal for what could be the next step in accelerating the breeding cycle, the in vitro nursery and its applications is discussed.


Copyright Owner

Gerald Neil De La Fuente



File Format


File Size

152 pages