A New Self-Compatible Asian Pear: 'Sweet Cost'

Abstract

'Sweet Cost', a new self-compatible Asian pear cultivar carrying the S ₄ ^sm(SM, stylar-part mutant) allele, was developed from a cross between 'Wonwhang' (S ₃S ₅), the main early-maturing pear cultivar with high fruit quality in Korea and the self-incompatible '92-18-31' (S ₄ ^smS ₄ ^sm) obtained from self-crossing of 'Osa-Nijisseiki' (S ₂S ₄ ^sm), a self-compatible bud mutant that originated from self-incompatible 'Nijisseiki' (S ₂S ₄). The cross was made in 2000 at the National Institute of Horticultural and Herbal Science, Rural Development Administration in Korea. It was first selected as '2000-10-22' in 2006 for its attractive eating quality, good appearance and self-compatibility. After regional adaptability tests at 10 sites for 5 years from 2008 to 2012 as 'Wonkyo Na-61', it was selected and named in 2012. It bloomed 1 day earlier than 'Osa-Nijisseiki' and 1 day later than 'Wonwhang' in 2007 - 2012. It is medium in tree vigor and has an upright-spreading tree habit. 'Sweet Cost' is classified as susceptible to pear scab (Venturia nashicola),similar to 'Osa-Nijisseiki'. Its S-genotype, determined using PCR-RFLP, is S ₃S ₄ ^sm. 'Sweet Cost' had a 49.5% fruiting rate by self-pollination. The average optimum harvest time of 'Sweet Cost' was 138 days after full bloom and it matured around one week earlier than 'Osa-Nijisseiki' and one week later than 'Wonwhang'. The fruit is roundish oblate in shape and yellowish brown in skin color. Average fruit weight was 464 g and soluble solids concentration was 12.2°Brix. The flesh had abundant juice and negligible grit.