A tiller inhibitor gene in wheat and its effect on plant growth

A recessive gene that inhibits tillering was identified in a wheat (Triticum aestivum L.) from Israel. The locus for tiller inhibition, designated Tin, is linked to the locus for hairy glume (10 � 3 map units apart) and black awns, and hence is presumed to be on the distal end of chromosome IAS. Such a gene has been proposed as desirable for wheat in both low and high input environments. Serial sowings were made every 21 days between autumn and spring in buckets outdoors with lines differing in tillering. At a harvest at the 4.5 leaf stage, tillering was less in the low tillering lines than in the conventional lines in all sowings, but leaf area and weight per plant were unexpectedly higher. Stunting, which is a characteristic of low tillering lines when temperatures are low and daylength long, became apparent in one of the low tillering lines in sowings made in late winter and spring at a time when daylength was 11.5 h and increasing. In four populations segregating for the tillering trait, low tiller number was associated with a higher harvest index, reduced height, an increased duration of the flag leaf life and of grain filling, a lower leaf to stem weight ratio at maturity, higher specific leaf weight, higher stem density and a higher kernel number per unit stem weight. Traits likely to severely limit crop yield other than stunting were not found.