Waterlogging differentially affects yield and its components in wheat,barley, rapeseed and field pea depending on the timing of occurrence

Waterlogging on croplands is increasing in various areas of the world. This study evaluated the yield penalty by early and late waterlogging on wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), rapeseed (Brassica napus L.) and field pea (Pisum sativum L.). Plants cultivated outdoors were exposed to a 14-day waterlogging during vegetative (at 65 days after sowing (DAS)) or reproductive (at 85/87 DAS) stages, followed by drained conditions until maturity. Yield (seed weight per plant) and its components (number of spikes/siliques/pods per plant, number of grains per spike/silique/pod and 1,000 grain weight) were assessed at maturity, along with morphological (number of tillers/branches) and shoot and root dry weight responses after waterlogging and during recovery. Wheat was the most tolerant species achieving 86% and 71% of controls in yield with early and late waterlogging, related to fewer grains per spike. Barley and rapeseed tolerated early waterlogging (yields 85% and 79% of controls) as compared to late waterlogging (32% and 26% of controls), mainly due to fewer spikes per plant (barley) or reductions in seeds per silique (rapeseed). Field pea was greatly affected by waterlogging at both timings, attaining a yield of only 6% of controls on average due to much fewer pods and fewer seeds per pod. So, wheat could be an option for areas facing either winter or spring transient waterlogging (i.e. early or late stages); barley and rapeseed are recommended only with if water excess occurs in early stages and field pea is intolerant to waterlogging.