「土佐文旦」と「水晶文旦」との交雑実生における染色体数の変異

Abstract

To breed pummelo (Citrus grandis [L.] Osb.) varieies with a few seeds, a female parent 'Tosa-Buntan' and a male parent 'Suisho-Buntan' were crossed ; the seed weight and the chromosome number of the progenies were determined from 1996 to 1998 inclusive. The weight of full developed seeds peaked between 301mg to 330mg. Those which weighed less than 30mg were considered to be unfertilized ovules. About 20% of partially developed seeds weighed between 31 to 180mg. Embryos rescued from seeds, weighing between 61 and 180mg, germinated better under embryo culture than when sown in plug trays. Hence, embryo culture is an effective means of obtaining seedlings from these poorly developed seeds. Furthermore, about 15% of them were not diploid. Chromosome counts of 128 embryo cultured seedlings derived from seeds weighing between 61 and 180mg revealed that there were 109 diploids, eight triploids, three tetraploid, and eight aneuploids. The aneuploids had chromosome numbers of 2n=17, 19, and 28.