Preharvest sprouting tolerance in three triticale biotypes

Abstract

Preharvest sprouting is a major constraint to the utilization of triticale for human consumption in regions where moist, humid conditions prevail during harvest. To examine variation for different components of preharvest sprouting tolerance (PST), trials were conducted over six environments in Mexico. Seed dormancy, bract related chemical and mechanical inhibitory effects and falling number (FN) were measured in primary and secondary triticales and their wheat and rye progenitors. Seed dormancy contributed 78% to PST with significant variation among and within triticale biotypes and progenitor species for bract water soluble inhibitors, bract mechanical barriers and FN. Bract chemical inhibition was higher when soil moisture was non-limiting in moisture-stress/non-stress experiments, suggesting the presence of inhibitors other than abscisic acid. In combination, tolerance components enhanced PST. Substituted triticales [2D(2R)] showed higher seed dormancy and bract related tolerances compared with other triticale biotypes and displayed PST equivalent to wheat. The higher PST in wheat could be attributed to higher FN levels. Components of PST evident in the wheat and rye progenitors were suppressed by wheat/rye genomic interactions in primary triticales. The selection of triticales with high stable FN will be an important first step in the development of PST cultivars, by providing the building block upon which seed dormancy and other related factors can be introduced.