GROWTH AND DEVELOPMENT OF UNICULM AND CONVENTIONAL-TILLERING BARLEY LINES

Barley (Hordeum vulgare L.) producers in northern regions require genotypes that develop and mature rapidly. Although the phenological development of barley has been studied extensively, the effect of the uniculm character on rate of growth and development has not been investigated. The objective of this study was to compare the growth and development of uniculm and conventional-tillering near-isogenic barley lines. Three pairs of near-isogenic lines that differed by the presence of the uc2 (uniculm) gene were evaluated at Palmer and Fairbanks, AK during the 1990 and 1991 growing seasons. Averaged over four environments, uniculm genotypes required more growing degree days (GDD) to reach double ridge formation, but there were no differences for GDD to terminal spikelet formation (P < 0.01). Uniculm genotypes had 0.3 more leaves per main culm, required 12 fewer GDD to reach full flag leaf extension, and had a leaf appearance rate that was 0.12 leaves (100 GDD)-1 faster than conventional genotypes (P < 0.01). Uniculm genotypes matured 23 GDD earlier and were 10.9 cm taller than their conventional counterparts (P < 0.01). The restriction of a single culm per plant decreased kernels per spike by 2.2 kernels and increased kernel weight by 8.4 mg (P < 0.01). Our results suggest that the uniculm phenotype results in several favorable modifications of phenological development, which may be of practical value in regions where early maturity is important.