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Developmental Allometry and Its Implication to Grain Yield in Barley

Zakri A. Hamid, J. E. Grafius
Crop science 1978 v.18 no.1 pp. 83-86
Hordeum, allometry, backcrossing, barley, culms, cultivars, gene pool, genotype, grain yield, leaf area, leaves, photosynthesis, plant organs, seeds, tillers, yield components
Five parental pairs of barley selections (Hordeum vulgate L. Emend. Lam) exhibiting differences in leaf area (S) and culm diameter (D) were used in this experiment. The crosses and backcrosses to each parent were allowed to self to the equivalent of the F₄ at which time 20 random plant selections were drawn from each of the 15 populations. Seed was increased for two generations and standard nursery plot trials were conducted on the equivalent of the F₇. The objectives were to observe the allometric relationships among leaf area, culm diameter, and the yield components, and to relate these relationships to differences in yield between the 15 populations. Evidence was presented to show that earlier-developed organs have a profound influence on later-formed structures. A striking relationship was observed between the number of fertile tillers per unit area (X) and all the other plant organs involved. It was found that X was negatively correlated at a highly significant level with culm diameter (D) and the average leaf area (S). The pattern was clear: when the number of tillers increased, the size of the organs on each tiller tended to decrease. In other words, a genotype with a high number of tillers tended to have smaller culm diameters, smaller leaves and smaller heads. In addition, highly significant correlations were observed among D, S, and Y (number of kernels per head). Grain yield (W) was not significantly associated with either D or S, although the two traits may be strongly correlated with one or more of the three components of yield. With this gene pool and in this particular growing environment, the components of yield were more limiting than the size of the photosynthetic surface in causing variation of grain yield among these cultivars.