Remobilization of water soluble carbohydrates in non-leaf organs and contribution to grain yield in winter wheat under reduced irrigation

The remobilization of water soluble carbohydrates (WSC) has an important role for grain yield. This study investigated the accumulation and remobilization of WSC in non-leaf organs (chaff, upper stem, and lower stem) and their contribution to grain yield, under different irrigation levels (rainfed, reduced irrigation, and full irrigation) and seeding rate treatments (450, 600 and 750 plants m   -2) using two winter wheat cultivars, Shijiazhuang 8 (SJZ-8) and Lumai 21 (LM-21), in two field experiments. Results showed that decreasing irrigation and increasing seeding rates increased WSC accumulation and remobilization, remobilization efficiency, and contribution to grain yield in non-leaf organs. When the organs are ranked from highest to lowest in terms of the WSC accumulation amount, remobilization amount, remobilization efficiency, and contribution to grain yield, they are: the lower stem, the upper stem, and then the chaff. And between cultivars, these amounts were higher in SJZ-8 than in LM-21. The total contribution, pre-anthesis contribution, and post-anthesis contribution of WSC remobilization from all non-leaf organs to grain yield ranged from 11.7 to 21.5%, 4.8 to 9.4%, and 6.9 to 12.1%, respectively. This increase in WSC accumulation, remobilization, and contribution to grain yield in non-leaf organs is an important reason high grain yields can be maintained in water-saving and optimal high density management systems.