Quantifying the contributions and losses of dry matter from non-surviving shoots in four cultivars of winter wheat

The total dry matter in non-surviving shoots and the amount of this contributed by their own carbon fixation was quantified for four winter wheat cultivars in two UK field experiments in 1995-1996 and 1997-1998. Amongst the cultivars studied (Brigadier, Rialto, Soissons and Spark) the maximum shoot number ranged from 1000 to 1600 m(-2) and the percentage of shoots which died ranged from 32 to 63%. Cultivars for which shoot death was both great in number and late in development contributed most dry matter from their own carbon fixation (170 g m(-2)), but lost more dry matter when they eventually died (290 g m(-2)), resulting in a net loss of > 100 g m(-2). Non-surviving shoots belonging to cultivars with more economic patterns of tillering also caused a net loss of dry matter, but this was substantially less at 10-50 g m(-2). It is concluded that non-surviving shoots will reduce yield potential in the majority of situations by competing for assimilate with the developing ears in fertile shoots and that the detrimental effects are likely be most acute in drought situations. We have identified large genetic variation in the potential amount of dry matter wasted by non-surviving shoots that can be exploited to minimise their detrimental effects. (C) 2002 Elsevier Science B.V. All rights reserved.