DIPLOIDIZATION OF CUCUMBER (CUCUMIS-SATIVUS L) HAPLOIDS BY COLCHICINETREATMENT

Haploid cucumber plants are totally infertile and do not undergo spont aneous diploidization. The use of haploids depends on the possibility of doubling the chromosome number and the obtaining of stable doubled haploids DH. Four haploids of different genotypes propagated vegetativ ely were treated with colchicine in order to obtain DH. The following procedures were used: I) apical shoot meristem treatment, 2) soaking o f shoot explants, 3) placing of shoot explants on medium with colchici ne. Plants of the C1 generation were evaluated in respect to morpholog ical and cytological characters and fertility. The best result of 20.9 % DH was obtained after repeated treatment of the meristem with colchi cine. A large group of chimeras (28.5%) was also distinguished as were haploids and tetraploids. DH plants were fertile and gave uniform pro geny. Chimeras had a decreased fertility and showed disturbances in me iotic divisions.