Abstract
Excess moisture injury is a serious constraint for common wheat production in Japan. We hypothesized that the excess moisture injury (EMI) is mainly caused by water and nutrient deficiency due to inhibited root function, and thus aimed to examine if the basal application of controlled–release fertilizer (CRF) to surface soil and the top-dressing with quick-acting fertilizer would mitigate EMI. We used cv. Norin 61 for pot experiments for four years. Temporal waterlogging was imposed in the pots to cause EMI whose intensity was regulated by adjusting the water tables. The application of CRF to the 3 cm surface layer increased nitrogen uptake by the plants more than that to the 10 cm depth or deeper layer,irrespective of the degree of EMI. Thus top-dressing was found to be effective even after the symptom of EMI appeared, and it enhanced nitrogen uptake to the level equivalent to that in the plants top-dressed without EMI. The top-dressing not only enhanced nitrogen uptake by roots in a shallow layer but, in some cases, also promoted the function of roots injured by excess moisture to absorb the released nitrogen from CRF. We therefore conclude that a combination of basal application of CRF to the shallow layer and top-dressing of quick-acting fertilizer is an effective technique to mitigate EMI and promote recovery from such injury by utilizing the roots in the shallow layer that tend to maintain a relatively high function under excess moisture conditions.
