Search for sweet cherry (Prunus avium L.) cultivars suitable for warm climate in the southwestern region of Japan

The cool climate of the northern part of Japan’s main island, Honsyu is suitable for the cultivation of sweet cherry (Prunus avium L.). In recent years, the warm southwestern region of Japan has also been proposed as a candidate region for cherry cultivation; cherry fruit set has, however, previously been reported to be significantly inhibited under warm climate conditions before flowering. We aimed to identify a suitable cherry cultivar for cultivation in the warm southwestern region by examining five cherry cultivars: ‘Summit’, ‘Benitemari’, ‘Kokanishiki’, ‘Benisyuho’, and ‘Saori’. Trees were grown in 2013 and 2014 in Matsue city, Shimane prefecture, Japan, (35°28’N; 133°03’E) with an annual mean temperature of 14.9°C, annual means of maximum and minimum temperature of 19.9 and 11.6°C, respectively (2013) and annual precipitation of 1787.2 mm. The data showed that the full bloom dates were around mid-April. These cultivars could all cross-pollinate one another. The fruit set of the cultivars was over 10% but that of ‘Summit’ was only 5.7% in 2013. Harvesting time was overlapping in June (June 1-20 in ‘Kokanishiki’ and ‘Benisyuho’, June 1-30 in ‘Benitemari’, June 4-16 in ‘Summit’, and June 6-20 in ‘Saori’). Harvesting time in Shimane prefecture could be two weeks earlier than those in the Yamagata prefecture, primary cherry producing prefecture in Japan. The soluble solid content of ‘Kokanishiki’ and ‘Benisyuho’ cherries was over 20 °Brix, and ‘Kokanishiki’ softened more rapidly. With juice extraction ratios of between 30 and 40%, the fruits of all cultivars were juicy. We recommend ‘Benisyuho’ which possessed the highest quality as being the most suitable cultivar for cultivation in the warm southwest region of Japan; the other three cultivars, excluding ‘Summit’, were also suitable for cultivation in this area.