Abstract

Agropyron cristatum CB-9-85, was obtained from a seed treated with a 0.1% colchicine solution. The plant which displayed multipolar cell division was grown in the field to permit open pollination. The effects of colchicine-treatment were found to be inheritable. All F1 progeny of CB-9-85 showed abnormal chromosome segregation irrespective of their chromosome number, 7 II or 7 II+1 I. Multipolar cell division, univalents, unequal disjunction, precocious division, chromosome fragments, chromosome bridges and micronuclei were found related to the formation of multincleated and aneuploid pollen. Pollen fertility was related to the size of thr grain, with small grains displaying low fertility. Seed fertility in plants which did not form quartets was zero. Multipolar cell division is the only mechanism which can be demonstrated by experimental data that can explain genome segregation and chromosome elimination in natural population and a scheme is presented.