Exploring the differences between organic and conventional breeding in early vigour traits of winter wheat

Breeding for organic systems may be done as pure line or population breeding. Early vigour, critical to organic systems, was compared for different winter wheat breeding origins in a hydroponic system, as well as in the field. Entries were: the F-15 of composite cross populations (CCP5), based on high yielding (Y), high quality (Q) or Y*Q varietal intercrosses after 11 generations evolving under organic management; four organically bred; four conventionally bred baking quality varieties; a hybrid bread wheat and a high yielding variety. Hydroponic traits corresponded well with ground cover and plant height measured in the field. The organically evolved Q and YQ CCP5, organic varieties 'Poesie', 'Butaro' and 'Tobias' and the conventional 'Capo' were best suited for organic conditions. Compared to most modern varieties, CCPs had fewer seminal roots, their roots tended to be thicker and their root systems heavier, suggesting specific adaptation to penetration into deeper soil zones. Conventionally bred 'Capo' exhibits a diverse combination of root traits adaptive to a variable range of soil and environmental conditions, which may contribute to higher nutrient-use efficiency. Average root diameter of conventional E-varieties (0.28 mm) was significantly lower compared to organic varieties or the Q/YQ CCPs (both 0.30 mm). Specific root length of conventional E-varieties (17.5 cm mg(-1)) was significantly higher than for organic varieties (15.9 cm mg(-1)) and both differed from the Q and YQ CCPs (14.3 cm mg(-1)). Seminal root length and shoot length were identified as reasonable non-destructive predictors for direct selection within segregating materials and populations.