Genetic Variation for Canopy Architecture and its Use in Wheat Breeding¹

Genetic studies showed that two genes control the dense spike (short rachis internodes) of PI 190982 ( Triticum aestivum L., sphaerococcum group), a tall wheat cultivar from Spain that has erect and short leaves. Few genes, most likely two or three, controlled most observed differences in flag leaf angle and length. Selection allowed the isolation of erect‐leaved types that yielded about 45% more grain than PI 190982 but about 20% less grain than standard cultivars. Erect and nonerect derived lines did not differ in yields between row spacings of 15 and 30 cm in field experiments in 2 years. PI 190982 appears to be a useful germplasm source for modifying canopy architecture, but the role of leaf erectness in reaching new high yield levels requires additional study.