New sweetpotato [Ipomoea batatas] cultivar "Harukogane" [Japan]

"Harukogane" or "Sweetpotato Norin 50" is a new cultivar released for fresh market use by the National Agriculture Research Center (NARC). It underwent trials throughout the temperate zone of Japan as the breeding line "Kanto 108". It was officially registered as "Sweetpotato Norin 50" in 1998 by the Ministry of Agriculture, Forestry and Fisheries. "Harukogane" was derived in 1987 from a cross between "Kanto 103" and "Beniazuma". This new cultivar produces prostrate but non-twining vines. Leaves are slightly dentated, heart shaped and the color of the immature leaf is pale green. The storage roots are long-fusiform with a dark red-purplish skin and yellow flesh. Steamed root taste is the same as that of "Beniazuma." Storage root yield of "Harukogane" is 20-30 % higher than that of "Beniazuma" in NARC. In Okinawa Prefecture where "Harukogane" is expected to be practically cultivated, storage root yield is less than that of "Okihikari" which is a popular cultivar in Okinawa having a yellow flesh. Storage root shape, uniformity, and the eating quality of steamed roots are also superior to those of "Okihikari." "Harukogane" is slightly susceptible to black rot (Ceratocystis fimbriata) and root knot nematode (Meloidogyne incognita), susceptible to Fusarium wilt {Fusarium oxysporum f. sp. batatas), and moderately resistant to soil rot (Streptomyces iponoeae). Storage roots can be adequately stored in winter