Seed size influences the coleoptile length of wheat

Abstract

Variation in coleoptile length within and between 2 cultivars of semidwarf wheat (Triticum aestivum) was related to seed size. Seeds of cvv. Banks and Kite were separated by sieving for width into the size classes of >2.75, 2.75-250, 2.50-2.25 and 2.25- 2.00 mm. The mean grain weights of ungraded samples were 43.1 mg (Kite) and 34.3 mg (Banks), and for the subsamples were 52.4, 37.9, 30.4 and 20.7 mg (Kite) and 41.4, 33.2, 25.8 and 19.1 mg (Banks). The effect of size class on coleoptile length was significant (P<0.01). Over both cultivars, coleoptile length declined by 0.37 mm per mg reduction in seed weight. Kite produced the longer coleoptiles overall, 87.5 mm compared with 59.0 mm for Banks. However, only 3.3 mm of this difference can be accounted for by the mean difference in seed weight (8.8 mg) and the effect of seed weight on coleoptile length (0.37 mm/mg). Genetic differences, apart from adult plant height, appear to explain most of the difference in coleoptile length between the cultivars. There was considerable genetic variability within genotypes. In Banks, with seed width >2.75 mm (41.4 mg per seed), the lengths of coleoptiles ranged from 24-89 mm (mean 65.1 mm), suggesting considerable scope for the selection of genotypes with longer coleoptiles.