Variation and inheritance of certain characters of brome grass, Bromus inermis Leyss

The primary objectives were studies of the inheritance of leaf spot infection, of beta-carotene content, and of the effects of self-fertilization on plant characters of probable importance in brome grass. Clonal lines and 1-year-selfed progenies of both the Parkland and creeping types were used. A study of hot-water methods of bulk emasculation was made also. Highly significant differences in reaction to leaf spot, Selenophoma bromigena, were found between clonal lines tested in a replicated nursery under artificial epidemic conditions. A considerable proportion of the 1-year-selfed lines tested in an individual plant nursery proved superior in leaf spot resistance to the commercial variety of their respective type. Highly significant r values of +0.63 and +0.66 were obtained for reaction to leaf spot of 1-year-selfed progenies and their parental clonal lines with the Parkland and creeping types, respectively, grown under comparable artificial epidemic conditions. Studies were made of a number of agronomic characters on the clonal lines of both the Parkland and creeping types tested in a replicated nursery and also of their 1-year-selfed progenies tested in an individual plant nursery. Significant differences were found within each group for all the characters studied with only a few exceptions. Some vigorous lines were found in the selfed group which were equal or superior to the commercial check variety for each character studied. Plant characters including yield of hay, basal diameter, vigor of recovery, and leaf width were found to be inherited in brome grass as the selfed progenies were highly correlated with their parental clonal lines. Significant differences for heat and drought resistance were found among the clonal lines of both the Parkland and creeping types and also among their selfed progenies. The relationships for heat and drought resistance between the parental clonal lines and selfed progenies of both the Parkland and creeping types were found to be positive, but neither of the two r values calculated reached the 5% level of significance. There were significant differences for beta-carotene content among the clonal lines of both types of brome grass. The data on individual plants of 1-year-selfed progenies showed rather wide variations within and between lines in their content of beta-carotene. Heritable variations in beta-carotene content were found in creeping brome grass as indicated by a significant r value of +0.76 obtained for the parental clonal lines and their selfed progenies. Spectrographic analyses of content of six mineral elements were made upon 36 clonal lines of creeping brome grass. Significant differences were found only for the content of Mg and of K between these lines. Interrelationships of plant characters were studied with clonal lines of both types of brome grass. Relationships of importance were summarized. Treatment of panicles of brome grass with hot water at a temperature of either 47 degrees C for 3 minutes or 48 degrees C for 1 minute was found to be a relatively satisfactory method of bulk emasculation.