A NATURAL AMPHIDIPLOID FROM AN ONION SPECIES HYBRID

Abstract

A fertile amphidiploid has been obtained from a cross between Allium cepa var. Australian Brown and A. fistulosum type Nebuka. Second generation plants are very uniform in appearance and set seed readily. This amphidiploid shows greater vegetative vigor than either parent, as evidenced by increased height, larger sto-mata, larger flowers, larger pollen grains, greater weight of seed, and more rapid growth of seedlings. It is a perennial like Nebuka. The haploid number of chromosomes in the amphidiploid is sixteen. Meiotic behavior is fairly regular. Sixteen bi-valents are generally found at first meta-phase. Fragments, chromatin bridges, and micronuclei were observed but were not as common as in the diploid hybrid. During meiosis both the random and localized type of chiasma formation are found in different bivalents in the same cell.