DEVELOPMENT OF ABNORMAL FLOWERS IN GENERATION OF DOUBLED HAPLOIDS OF SUMMER SQUASH (CUCURBITA PEPO L.)
The culture of unpollinated ovules in vitro in summer squash was used to develop fully homozygous breeding lines with the aim of the speeding-up breeding program. As a resuit of assessment for economically valuable traits, the seven promising DH-lines obtained from summer squash accessions differed by fruit shapes and colours were selected out. All breeding lines produced showed high homogeneity that retained in following generations and also have an appropriate set of economically valuable traits. DH-lines belonging to female type have up to 96% female flowers and only 4% male flowers. It is very important for breeding when the male flowers appeared in two weeks just after the female flower began blooming. The development of morphologically abnormal female and male flowers, along with gynandromorphy flowers was noted on selected DH-lines. During vegetation period from 26 to 36 flowers appeared on the plant, where out of them 19-21 ones were normally developed female flowers, 3-5 ones were normally developed male flowers, and up to 10-11 ones showed an abnormal way of development. The percentage of abnormal flowers stayed invariable when growing in greenhouse condition with high humidity and temperature as well as in open field condition. As it was shown the development of deformed abnormal flowers inherited and manifested in the following generation after self-pollination. As a result of the study, the occurred anomalies in course of male and female flower development in summer squash (C. pepo L.,) DH-lines produced through a cultivation of unpollinated ovules in vitro were described in details for the first time.