Use of potted seedlings for reducing damage by rice water weevil in transplanted rice plants

Abstract

Rice cultivation using potted-seedlings is practiced mainly in cold regions. The technique limits plant injury during to transplanting and promotes tillering ability, which may in turn reduce damage to rice plant roots by the rice water weevil (RWW) early in the growing season. We assessed the effect of RWW infestation on the growth and yield of rice by releasing RWW adults on rice plants cultivated from potted and conventionally grown seedlings in the field and in pots. In the field experiments, the tiller number of rice plants exposed to RWW tended to be lower than in control rice plants grown from potted and conventional seedlings during the early growing season (40 to 50 days after transplantation (DAT) ). In addition, the tiller number of rice plants cultivated from potted seedlings tended to be higher than the tiller number of plants cultivated from conventional seedlings. In the pot experiments, above-ground dry biomass, root dry biomass, and exudation rate tended to decrease after RWW infestation in rice plants cultivated from potted and conventional seedlings. However, these parameters tended to be higher in rice plants cultivated from potted seedlings than from plants cultivated from conventional seedlings. The findings suggested that using potted seedlings reduces the potential for damage by RWW during the early growing season. However, since the tiller number of many of the rice plants damaged by RWW had recovered by the heading stage in the field, the benefits of using potted-seedlings to minimize RWW damage early in the growing season is not reflected in improved rice yield.