Relationship of glaucousness and epicuticular wax quantity of wheat

Abstract

The quantity of epicuticular waxes of crops such as wheat (Triticum spp.) influences water relations, wettability by pesticide sprays, and resistance to insects and diseases. Determination of wax quantity for selection purposes is difficult, whereas visual selection for degree of glaucousness would be simple. However, the relationship between wax quantity and glaucousness is unclear. Common (T. aestivum L.) and durum (T. turgidum L. var. durum) inbred genotypes, nonglaucous/glaucous isogenics, and segregating families were grown under field conditions near Swift Current, Saskatchewan. Waxes were extracted with petroleum ether and determined gravimetrically for flag leaf sheaths, blades or spikes sampled 1–2 wk post-anthesis, and compared with visual glaucousness ratings. Wax quantity was generally lower for nonglaucous than for glaucous genotypes, but there was some overlap of observed quantities for the two groups. On average, wax was 44% greater for glaucous than for nonglaucous durum genotypes, and 32% greater for glaucous than for nonglaucous common wheat genotypes. Visual selection for glaucousness is thus likely to produce differences in epicuticular wax quantity, but the quantity difference would have to be verified at advanced generations. Key words: Triticum aestivum L., Triticum turgidum L. var. durum, glaucousness, epicuticular wax