Plant emergence and establishment is a critical issue in modern farming systems, particularly with the adoption of minimum tillage practices. Poor plant emergence and establishment can affect early plant vigour, weed competition, water use efficiency and, ultimately, grain yield. Poor establishment can be a problem in covered barley but is a frequent and more serious problem in hulless barley. For the successful development of a hulless barley industry, this issue needs to be thoroughly investigated and solved.
Initially, we considered emergence and establishment problems to be associated with the embryo being damaged during harvesting, resulting in poor seed viability and germination. Despite modification to harvest and seed cleaning procedures, we continue to be frustrated by yield trials with variable and inconsistent plant emergence and establishment.
In 1998 yield trials, the actual number of emerged plants ranged from 75 plants/m2 to 95 plants/m2 for hulless genotypes and from 120 to 140 plants/m2 for covered genotypes. Variations in plant establishment and seeding rate make interpretation of grain yields comparisons between hulless and covered genotypes very difficult. To compensate, the number of seeds sown/m2 in yield trials in 1999 were increased from 150 to 180 seeds/m2.
Preliminary investigations into the morphology of the coleoptile revealed that hulless barleys may produce a shorter coleoptile than covered barleys. In addition, hulless barleys appear to be more susceptible to growing an ‘abnormal’ coleoptile particularly when the embryo is damaged.
It is likely that a large proportion of variation for coleoptile length is under simple genetic control. Selection for improved coleoptile length in hulless barley, therefore, may improve establishment.
The aim of this study was: a) to determine the relative differences in coleoptile length between hulless and covered barley genotypes, b) to determine the effect of grain damage on coleoptile length in hulless barley and, c) to identify chromosomal regions conferring coleoptile length in barley which could, in turn, be used to select for coleoptile length in hulless barley.