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Thesis (M.S.)—University of Nebraska—Lincoln, 1954. Department of Agronomy.


Copyright 1954, the author. Used by permission.


Investigations on inbreeding and outcrossing were conducted in connection with the bromegrass breeding program at the Nebraska Agricultural Experiment Station in 1952-53. Studies were conducted to determine the effects of self pollination, sib pollination, cross pollination and open pollination on the production of seed of bromegrass and on the performance of the resulting progenies. This study was made by comparing the results from the following: two years of self pollination; one year of selfing and one year of cross pollination; and one year of selfing and one year of open pollination.

Average numbers of seeds per panicle and per spikelet from different modes of pollination showed that continued inbreeding by selfing in parchment sleeves gave only half as much seed as controlled sibbing or crossing. Twice as much seed or more was obtained with open pollination as with controlled pollination. Seed produced on the panicles not enclosed in the sleeves was nearly twice as heavy as that produced on the panicles enclosed in the sleeves, regardless of mode of pollination, thus indicating a significant sleeve effect. Inbred seed appeared to have a lower percent of germination than the cross-fertilized seed. All of the seed produced on panicles in the sleeves had a lower percent of germination than the open-pollinated seed.

The leaf and plant height of the inbred plants were shorter than those characters of the hybrids. The hybrid progenies averaged the same height as Lincoln bromegrass but hybrids of some lines were taller. The average number of flowering culms was smallest on the inbred progeny. The difference in the number of vegetative shoots among the modes of pollination was relatively small. The average forage index ratings for the progenies from all modes of pollination and the plants used as checks showed that the hybrids and checks were the best forage plants. The average forage index ratings indicate that the self-pollinated progenies were slightly inferior to the sib-pollinated plants.

Advisor: L. C. Newell.