MORPHOLOGY, FERTILITY AND CROSS-COMPATIBILITY OF SOMATIC HYBRIDS BETWEEN BRASSICA-OLERACEA L AND BRASSICA-CAMPESTRIS L

Thirty-one somatic hybrids between a heat tolerant cabbage cultivar 'Y oshin' (Brassica oleracea var. capitata L.) and a Chinese cabbage cult ivar 'Kenshin' (Brassica campestris var. pekinensis L.) were obtained with the aim of breeding new Brassica vegetables adapted to tropical a reas. After excluding two hexaploid somatic hybrids, 29 individuals we re investigated for pollen fertility and seed set after self-pollinati on and back-crossing with the parental species. All 29 amphidiploid so matic hybrids showed pollen fertility higher than 70%, and 28 set seed s by self-pollination (2.2 seeds per silique). The hybrids were cross- compatible with Chinese cabbage (1.5 seeds per silique), while practic ally incompatible with cabbage. Progeny lines obtained by self-pollina tion had larger leaves than, and intermediate leaf shape of, the paren tal species. The lines obtained by back-crossing with Chinese cabbage showed larger leaves than the parents and similar leaf shape to Chines e cabbage. These progeny lines, on the whole, exhibited an appreciably wide variation in both leaf size and shape. Variation was found also within the lines for leaf shape. The somatic hybrid method, therefore, could provide new genetic variations to be used to develop new vegeta ble cultivars.