Tillering in Barley: Genotype, Row Spacing, and Seeding Rate Effects1

Abstract

Production of tillers and their subsequent survival are important events in growth and development of barley (Hordeum vulgare L.) that affect the number of spikes produced per unit land area. Studies were conducted at St. Paul and Crookston, MN to evaluate tiller production, tiller mortality, and yield of 10 barley genotypes with different tillering capacities. In addition, these studies evaluated the influence of row spacing and seeding rate on tillering.The genotypes differed significantly in shoot and spike number. Shoot number for the highest tillering genotype was 42 to 71% greater than for the lowest, depending on the study, but the genotypes ranked consistently over years and locations. The high tillering genotypes tended to form tillers more frequently at the coleoptile node, in the axil of the third leaf, and from the primary tiller in the axil of the first leaf on the main shoot. In general, absolute shoot mortality (difference between maximum shoot number and spike number) was higher in the high tillering genotypes. Genotype M72‐269 was an exception to this generalization in having high shoot number and low shoot mortality.Row spacings of 7.5 and 15 cm had more shoots per unit area than the 30 cm spacing. However, narrower rows also had higher shoot mortality which led to similar spike numbers for the three row spacings. Higher seeding rates of 101 and 134 kg ha‐1 increased shoot number and spike number compared to the 67 kg ha‐1 rate. Changes in row spacing and seeding rate did not differentially affect shoot production or absolute shoot mortality among the genotypes.Grain yields of both low and high tillering genotypes were as high or higher than those of intermediate tillering cultivars. The extremely high and low tillering genotypes were not consistent in their yield performance at Crookston, suggesting a possible association between tillering capacity and yield stability. Small stem diameter and a tendency to lodge were characteristic of the high tillering genotypes. Identification of apparent genetic diversity for tiller mortality provides material for further study of the relationship between tiller mortality and yield.