Production of haploid plants using techniques such as anthers and ovule culture has long been considered important for genetic studies and plant breeders. These haploid plants can be used to produce homozygous dihaploid plants useful for plant breeding .This study is concerned with the production of dihaploid plants of Cucurbita pepo L. from ovule culture technique, gynogenic plants of squash were successfully produced by in vitro culture from unpollinated ovules at one day before anthesis. The ovules were placed on two media induction. Two temperature procedures were compared: 1) cold pre-treatment at 4ºC for 0,8,16 days of all three genotypes. The highest number of plantlets per 100 ovules was obtained from Rosina (22.5) ovules cultured on MS medium supplemented with 1.0 mg/l 2,4-D and 1.0 mg/l Kin without cold treatment. While Eskandarani cv. gave the highest number of embryogenic callus on MS medium supplemented with 5.0 mg/l 2,4-D at 8 days . 2) Cold (4ºC) and heat (35ºC) shocks post-treatment of Eskandarani cv. for 0, 4, 8, 16 days. The highest number of plantlets per 100 ovules (17.0) was obtained from ovules cultured on MS medium supplemented with 5.0 mg/l 2,4-D at 35ºC for 16 days, On the other hand, the highest number of embryogenic callus (100.0) was obtained from ovules cultured on MS medium supplemented with 5.0 mg/l 2,4-D at 4 days for 35ºC. Plantlets were acclimatized in the controlled environment. In each genotype, the root tips of plantlets were cytologically examined for ploidy level.
The derived plants are classified to 64% haploid and 36 % diploid. Therefore, the ovule culture could be used as efficient method for haploid production in squash.