Study On In Vitro Culture Of Unpollinated Ovary Of Summer Squash (Cucurbita Pepo L.)

In order to obtain regenerated plants(R0) from embryo sac,unpollinated ovaries of 5 genotypes of summer squash(Cucurbita pepo L.) were cultured in vitro.The results showed that inductivity were influenced by genotype and culture medium.The development degree of ovule has a significant influence on induction rate of regenerative plants.The highest induction rate of regenerative plants were obtained from the ovary of one day before flowering,followed by the day of flowering,the lowest is from two days before flowering. Heat pretreatment in dark had an positive role,the best treatment was at 35℃for 5 days. Among the factor affected embryogenesis,phytohormone was indispensable,while it was the best for treat by 3mg/L2,4-D+0.25 mg/LNAA+1mg/L6BA.Embryologic research showed that the regenerated Embryo plants was via embryogenesis.Embryoid origined from the inner overy wall,ootid or synergid.Counting of chromosome of root cells and chloroplast in guard cells were utilized to identify ploidy of regenerated plants.The result showed that most of regenerated plants is diploid,followed by tetraploid and uncertained ploidy.Three hiploid plants were obtained from '281' only,is about 1.5%of detected regenerated plants of this genotype.The observation of regenerated plants(R0) indicated that most of the plants' character were in accord with provider and very few plants showed variation in morphological character of leaf and vine colour,and ovary shape.Compared haploid plants with the diploid plants, haploid plants grow slowly,and the size of organ is smaller,male flowers have no pollens, stigmas are deformed.