The Effects of Genes Controlling Barley Leaf and Sheath Waxes on Agronomic Performance in Irrigated and Dryland Environments1

Abstract

Epicuticular waxes have been associated with drought tolerance in numerous species. Several barley, Hordeum vulgare L., mutants have been identified that alter, generally lessen, epicuticular leaf and sheath waxes. These mutants have been used to study the biochemistry of leaf and sheath wax synthesis, however, they have not been examined for agronomic performance in droughty environments. Fourteen isolines and cultivars were grown in three irrigated and three dryland environments to determine the effect of barley leaf and sheath wax mutants on agronomic performance in irrigated and dryland environments. The irrigated environments had significantly greater yields and 1,000 kernel weights, but were not significantly different for test weight and kernel plumpness. A significant irrigated vs. dryland by cultivar interaction was found only for yield. No mutant isoline was significantly better than its normal counterpart for any of the agronomic traits measured in either the irrigated or dryland environments. Some of the mutant genes were deleterious as their isolines were significantly inferior to their normal counterpart in both the irrigated and dryland environments. Photosynthetic measurements made in a growth chamber were similar for the mutant isolines and their normal counterparts and were unable to explain the observed field inferiority of the mutant isolines.