Abstract:

Aims Decreasing root biomass might be an effective way to increase crop production under drought stress. A winter wheat with root excision was chosen to determine whether 1) root biomass or R/S (root/shoot ratio) is reduced by root excision, 2) competitive ability is reduced by root excision and its link with R/S and 3) competitive ability influences crop production.

Methods The effects of root excision on root-to-shoot relations, competition ability and yield characters of winter wheat (Triticum aestivum cv Changwu135) were investigated using a deWit replacement series in a pot study. Root excision was conducted from tillering to jointing. Two culture methods (mono and mixed) were compared. The effect of drought was estimated from two groups of plants, one group maintained at 75% soil FWC and a second at about 50%, after root excision. Soil water was controlled by weight daily. At grain maturity, plants for each pot were harvested, divided into shoot and root, dried and weighed.

Important findings The R/S was significantly reduced after root excision in monocultures irrespective of water condition. Furthermore, spike weight and aerial biomass of wheat after root excision were reduced in mixed cultures, indicating that the competitive ability of wheat was reduced after root excision. There was positive correlation between competitive ability and R/S in crop varieties, i.e., the crop with the higher R/S had higher competitive ability. In monocultures, spike weight and yield of wheat after root excision were reduced with a complete water supply. However, the spike weight and yield of wheat were higher after root excision than without excision under drought conditions. This study indicated that the crop with higher competitive ability has a higher production capability with a complete water supply and that the crop could obtain higher yield with the reduction in individual competitive ability under limited water.

Key words: root excision, competitive ability, yield, drought, winter wheat