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Hybridization between upland and lowland and within upland cytotypes of switchgrass
Abstract
This research was part of a program for developing switchgrass as a biomass energy feedstock. The main objective of this research was to evaluate the feasibility of using controlled hybridization as a breeding method for switchgrass. To accomplish this goal, several experiments had to be conducted. A technique to produce hybrids under controlled mating condition was developed. This procedure was used to make controlled crosses to conduct genetic studies related to incompatibility, cytoplasm inheritance, meiotic pairing, and morphological-genetic markers. The extent of heterosis between ecotypes and within the upland ecotype also was evaluated as well as a system of seed production that could be used to produce F$\sb1$ hybrid seed. The results indicate that in switchgrass a pre-fertilization incompatibility system exists that resembles the S-Z system previously reported in the Poaceae. Additionally a post-fertilization incompatibility system also exists that inhibits intermatings among octaploid and tetraploid plants that is similar to the endosperm incompatibility due to the endosperm balance number system found in other species. Pubescence in the base of the upper surface of the leaf blade was a useful marker to verify the hybrids from upland by lowland crosses. The viability of the hybrid seed and the normal meiotic chromosome pairing shown by the hybrids indicate a high degree of similarity between upland and lowland genomes. Another common trait between switchgrass ecotypes is the maternal inheritance mode of cpDNA. Heterosis was only expressed in seedling weight while no heterosis was exhibited for first year biomass yield either in specific hybrids or population hybrids. Across years and locations there was not a significant difference among solid stand, solid seeded row, and transplanted row seed production methods. These results indicate that the switchgrass seed yield obtained using transplanted seed production fields should be similar to that obtained by using solid stand and row plantings. Therefore if plants producing progeny with high heterosis are identified, the transplanting method could be a feasible method to produce hybrid seed of cultivars of switchgrass.
Subject Area
Agronomy|Genetics
Recommended Citation
Martinez-Reyna, Juan Manuel, "Hybridization between upland and lowland and within upland cytotypes of switchgrass" (1998). ETD collection for University of Nebraska-Lincoln. AAI9823378.
https://digitalcommons.unl.edu/dissertations/AAI9823378