Stability of fruit set of newly selected parthenocarpic eggplant lines

Abstract

New parthenocarpic eggplant ( Solanum melongena L.) lines (‘AE-P’ lines) with favorable fruit quality (according to Japanese preferences) were bred by hybridizing a parthenocarpic European cultivar (‘Talina’) with two Japanese cultivars (‘Nakate Shinkuro’ and ‘Nasu Chuukanbohon Nou 1’), which have high fruit set. To clarify the effects of the parental genes on fruit set, development, and productivity in the progeny lines, we examined the progeny's characteristics by means of cultivation tests during different seasons and at different temperatures. In the autumn–winter greenhouse test, all tested AE-P progeny showed higher total fruit set (including malformed fruit) than the ‘Talina2/1’ line (a parthenocarpic double-haploid line of ‘Talina’), and higher production of normal fruit than the Japanese cultivar ‘Senryo Nigou’. Fruit set (normal fruit) was 100% in lines ‘AE-P03’ and ‘AE-P10’, and we selected ‘AE-P03’ for further study. Under other cultivation conditions, the fruit set of ‘AE-P03’ was at least as high as that of the Japanese lines, and ‘AE-P03’ also had a higher rate of normal fruit production in early-summer tests under various conditions and in a winter test in a growth chamber. An emasculation study indicated that the high fruit set of the Japanese eggplant lines contributed to the improved fruit set of ‘AE-P03’. Thus, the combination of two genetic traits (the high fruit set of the Japanese cultivar and the parthenocarpy of ‘Talina2/1’) appears to be necessary for breeding eggplant cultivars with improved ability to endure the stress imposed by unsuitable cultural conditions such as hot condition.