Climate change impacts
Water temperature is extremely important for the cultivation of wasabi, which is more suited to cool climates; higher temperatures adversely affect growth. Water temperatures above the appropriate range are thought to suppress rhizome development and increase the incidence of pests. In recent years, stalk (Fig. 1) and soft rot (see Note 2) have increased in the Shimo-Ichida (see note 1), which is distant from water sources and has experienced severe fluctuations in water temperature. Damage caused by soft rot and other diseases is also increasing in wasabi fields at lower altitudes and higher temperatures.
Adaptation activity
Shizuoka Prefecture is cultivating a hardier variety of wasabi that is more drought-resistant and less sensitive to heat and other environmental factors (Fig. 2). The new variety is mainly intended for cultivation in lower-altitude fields (30% of total production) where productivity is declining.
Outputs / Expected benefits
It is expected that the effect of rising temperatures on wasabi cultivation can be mitigated by the development of wasabi varieties that have greater heat-resistance and are more adaptable to drought and other environmental issues.
(Note 1) Upstream cultivation areas close to spring sources, where water temperatures are stable, are "upper fields", and downstream, where temperatures are more variable, are "lower fields".
(Note 2) This occurs primarily in the rhizome, with dark, water-soaked lesions that spread rapidly, becoming grayish-white to light grayish-brown, causing softening and rot. Onset increases with warmer water, becoming more intense at 18-19℃ or higher.
