2025 Volume 27 Issue 1 Pages 39-50
In the southern part of Kyushu region, where about 40% of sweetpotato in Japan is produced, sweetpotato foot rot disease (foot rot disease) caused by Diaporthe destruens has done severe damage to sweetpotato production since 2018. Because the major cultivars for table use ‘Kokei No. 14’ and ‘Beniharuka’ are susceptible to this disease, new cultivars that can replace them are desired by farmers. ‘Benihinata’ is a new sweetpotato cultivar bred by NARO in 2023 for table use with strong resistance to this disease. From the 2 years’ experiments of the infested field by Diaporthe destruens, the foot rot resistance of ‘Benihinata’ was “strong”, which was much better than that of ‘Kokei No. 14’ (“moderately weak”) and that of ‘Beniharuka’ (“weak to moderately weak”). The other main characteristics of ‘Benihinata’ are as follows. The yield was higher than that of ‘Kokei No. 14’, but similar to that of ‘Beniharuka’ in standard and early production periods at the NARO Miyakonojo research station. The skin color of ‘Benihinata’ was “purple red” and the uniformity of storage root shape was “medium to moderately uniform”, and generally the appearance of the root was “medium to moderately good”. The steamed flesh color of ‘Benihinata’ was “light yellow white” which was lighter than those of ‘Kokei No. 14’ and ‘Beniharuka’. Using storage roots stored for 1 to 2 weeks after harvest, the brix value and texture of steamed roots were evaluated. The brix value of ‘Benihinata’ was higher than that of ‘Kokei No. 14’ and lower than that of ‘Beniharuka’. The texture of steamed storage root of ‘Benihinata’ was “medium” which was the same as ‘Kokei No. 14’ and ‘Beniharuka’. Even with a storage duration of three months, the texture of ‘Benihinata’ staid “medium”. This trait is clearly different from ‘Beniharuka’ with “moderately sticky” to “sticky” texture and is rather similar to ‘Kokei No. 14’. ‘Benihinata’ was evaluated in other fields in Miyazaki and Kagoshima prefectures from 2021 to 2023 which are target areas of its extension. The yields were 79% to 126% compared to ‘Kokei No. 14’. The texture of the storage root of ‘Benihinata’ was “powdery” to “moderately powdery”. From these results, ‘Benihinata’ is expected to mainly replace ‘Kokei No. 14’ and to contribute to stable sweetpotato production for table use in the southern part of the Kyushu region.
