Inheritance of phyllochron in barley

Phyllochron, defined as the time beta een elongation of successive leaves. influences the development of cereals. Small phyllochron may be advantageou s for barley (Hordeum vulgare L.) groan 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 environ mental effects on phyllochron have been extensively studied, the inheritanc e of phyllochron has received little attention. The purpose of this study w as 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 Hide range of phyllochron was observed in their progeny, ranging from 51.7 to 69.7 GDD leaf(-1) in on e cross and 53.0 to 67.9 GDD leaf(-1) in the other. In both crosses, phyllo chron was positively associated with time to maturity, but not with grain y ield, Selection for small phyllochron reduced time to maturity, but also re duced 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.