INFLUENCE OF SEEDING DATES, SEEDING RATES, AND FERTILIZERS ON TWO CULTIVARS OF BARLEY

Two commercially suitable barley cultivars were compared for three years at different dates and rates of seeding and fertility levels. Conquest was significantly higher in yield than Olli and the differential magnitude increased as seeding was delayed. Olli matured 5 days earlier than Conquest when seeded early and 9 days earlier when seeded late. The two cultivars gave the same response to seeding rates and fertilizer treatments, and yields from seeding rates were not differentially affected by fertilizer treatments. The seeding rate of 67 kg/ha, considerably below the average used in practice, gave the highest yields. There were no significant differences in unit volume or kernel weights attributable to different treatments. The results indicated that the use of Conquest in a delayed seeding program could markedly increase the unit area production in central Alberta.

Spatial Discrimination and Reversal Learning Involving Differential Magnitude of Reinforcement

Three experiments are reported in which choice in the acquisition of spatial discrimination and subsequent reversal learning was based on differential magnitude of reinforcement. Exp. I presented evidence suggesting the operation of an important frustration factor on the smaller-magnitude side in this type of discrimination, and revealed a significant effect of temporal distribution of reinforcement on reversal learning. Exp. II showed that, while differential-magnitude discriminations may be originally acquired as readily as reinforcement-nonreinforcement discriminations, the former are not reversed as readily as the latter, and both types are affected by the administration of forced trials guaranteeing equal response frequencies to the two sides as compared with allowing free choice on all trials. Exp. III, concerned with reversal learning as a function of the magnitude ratio and delay of reinforcement, provided further evidence of poor reversal performance under differential-magnitude conditions, but indicated that performance resembling that in traditional reversal learning may be found if the magnitude ratio is very high.