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Abstract
Haploid production using in vitro anther and ovule cultures has long been recognized as an important tool to produce haploid and homozygous double haploid plants for genetic studies and plant breeding programs. In the present study, androgenic plants were derived from anthers at mid to late uninucleate microspore stage, without filament, were excised from sterilized male flower buds of three summer squash cvs. (‘Gabbla’, ‘Eskandarani ’, and ‘Rosina F1 ’). Anthers were cultured on MS (Murashige and Skoog, 1962) medium containing 90 g/l sucrose and supplemented with either 5.0 mg /l 2.4-D, or 1.0 mg/l 2,4-D and 1.0 mg/l Kin. It was found that both media and cultivars affected callus induction and plantlets regeneration. ‘Gabbla’ gave the maximum callus weight/anther (0.450 g) on MS medium containing 90 g/l sucrose and supplemented with 5.0 mg /l 2.4-D. On the other hand, ‘Eskandarani’ gave the largest number of plantlets per dish (21.3) and per callus (4.3). Additionally, gynogenic plants of squash were successfully produced in vitro from ovules prepared from unpollinated female flowers excised one day before anthesis, when placed on MS medium containing 30 g/l sucrose and supplemented with either 5.0 mg/l 2,4-D, or 1.0 mg/l 2,4-D and 1.0 mg/l Kin. Two temperature procedures were studied. The first was cold pretreatment at 4ºC for 0, 8, or 16 days for all three genotypes. The highest number of plantlets per 100 ovules was obtained from Rosina cv.