Field performance of bromegrass strains from different regional seed sources

Striking differences in the success of bromegrass plantings on farms in Nebraska suggested a test of strains from different seed sources. Strains were obtained from old fields and known centers of seed production to represent the region of adaptation of the grass from north to south in the Great Plains. A field test including 24 strains from Canada, North Dakota, Nebraska, and Kansas was planted in September, 1939. The strains were observed and data obtained during three seasons. In all, a total of 60 such strains were observed in this and subsequently planted tests. On the basis of their origin and performance, the strains tested were placed into two general groups here referred to as northern and southern types. The strains of southern type produced more vigorous seedlings under short days of fall and early spring, were more tolerant of drought and heat, possessed more vegetative vigor, and were more productive under the conditions of this test than the strains of the northern type. The highest yields of forage of all strains were obtained in the second year after seeding, the yields by groups of strains increasing in order according to source of strains from north to south. The southern strains also gave their highest seed yields in the second year, outyielding the northern strains. The northern strains maintained relatively high seed yields in the third as compared to the second year of production, and accordingly gave somewhat larger seed yields than the southern strains in the third year. Southern strains produced a larger percentage of their total forage in early spring than the northern strains. Under the conditions of this study, the designations "early" and "late" are thus suggested for the strains of southern and northern type, respectively. The southern or early strains are preferred in the region served by these tests, since the relatively low production of late-producing strains may be further curtailed by recurrent spring and summer droughts. The effects of nitrogen fertilization on the forage and seed productions of the strains were measured. Both forage and seed yields, as well as the protein content of the forage, were increased by the fertilizer application. Other factors in the environment were apparently more important than the level of nitrogen availability in determining the relative yields of the strains, as all strains responded similarly to fertilization. The results of this study show that variations in bromegrass, similar to the variations in other cross-pollinated crops, occur from farm to farm as well as between regions. These variations appear to have resulted from the selective effects of environmental factors operating both before and after the introduction of this grass into the United States.