| Percentage emergence in Triticum aestivum as
affected by seeding rate, season, and variety A. M. SCHLEHUBER Oklahoma Agricultural Experiment Station, Stillwater, Oklahoma, U. S. A. As a result of poor stands of hard red winter wheat in certain years and locations in the semi-arid sections of the Southwestern U. S. A., farmers frequently resort to higher seeding rates. Not irifrequently the increased seeding rates do not produce the expected increased stands. Often the stands are somewhat better, i. e. more seedlings emerge, but the percentage emergence does not appear to be proportionate to the increase in seeding rate. In a study set up to determine certain yield components (number of spikes per unit of area, number of seeds per spike, and weight of seeds) as affected by variety and seeding rate, seedling emergence was also determined by variety, by rate, and by replication. The 3 varieties in the test - Concho C. I. 12517, Kaw C. I. 12871 and Triumph C. I. 12132 - are all commercially grown in Oklahoma and adjacent states. The varieties were seeded in 10 foot 4-row plots with 12 inches between rows and between plots at rates given in Table 1. Each variety and rate was seeded in 4 replications. Seedling counts were made in all 4 rows of each variety within each seeding rate. The tests were conducted two crop years, 1958 - 1959 and 1959 - 1960. Conditions for seeding as to moisture and seed bed preparation were good to excellent in the fall of 1958, but because of extremely heavy rains in the fall of 1959 seeding had to be delayed beyond optimum time (October 1). Consequently, seeding conditions were only poor to fair in the fall of 1959. The seeding rates (in pounds per acre), the number of seeds planted and the number of seedlings emerged per square foot, and the percentage emergence are given in Table 1. In the 1958 - 1959 season, the percentage emergence for the 20.8 pound seeding rate was significantly higher than for the other three rates. There was no significant difference in percentage emergence in the three higher rates. However, in the adverse year of 1959 - 1960, the picture was somewhat different. Again the lowest seeding rate produced the highest percentage emergence, although considerably less than in the previous year. However, for each variety save one, as the seeding rate increased, there was a decrease in the percentage emergence. The lone exception was for the variety Triumph at the 80-pound seeding rate, which had a slightly higher percentage emergence than the 60-pound rate. It can be noted that in 1959-1960, the emergence was be low 60% in 8 out of 12 cases. Based on purely physical aspects of the surface soil and of emergence, it would seem logical to expect a higher percentage emergence as the seeding rate is increased within limits. The factors responsible, be they of an inhibitory nature or otherwise, have not been investigated here and the answers are not apparent. |