Inheritance of Phyllochron in Barley

Phyllochron, defined as the time between elongation of successive leaves, influences the development of cereals. Small phyllochron may be advantageous for barley ( Hordeum vulgare L.) grown in cool or short‐season conditions, in order to increase the number of leaves produced from a given number of heat units, usually measured in growing degree days (GDD). Although environmental effects on phyllochron have been extensively studied, the inheritance of phyllochron has received little attention. The purpose of this study was to quantify the inheritance of phyllochron in barley, and determine its genetic relationship with other agronomic traits. Phyllochron, leaf number, and other traits were measured on parents and 33 double‐haploid lines in two crosses grown at Palmer, AK, for 3 yr. Heritability of phyllochron was 91.1% in one cross and 70.6% in the second. Despite the relative similarity of parents for phyllochron within each cross, a wide range of phyllochron was observed in their progeny, ranging from 51.7 to 69.7 GDD leaf −1 in one cross and 53.0 to 67.9 GDD leaf −1 in the other. In both crosses, phyllochron was positively associated with time to maturity, but not with grain yield. Selection for small phyllochron reduced time to maturity, but also reduced grain yield in one cross. These results indicate that phyllochron is a good measure of plant development, and that it is associated with time to maturity and other developmental traits.