Study on pre-fertilization barriers in the interspecific hybridization between Cucurbita pepo L. and C. moschata duchesne

The present investigation was conducted to evaluate the pre-fertilization barriers affecting interspecific hybridization between C. pepo and C. moschata at Punjab Agricultural University, Ludhiana during the year 2018. The different pollen and pistil parameters were compared among genotypes of both the species. The non-significant differences were recorded for pollen viability (87.60 to 91.26%), pollen germination (50.08 to 66.60%) and stigma receptivity among all the evaluated genotypes. However, significant variations were observed for the in vitro pollen tube growth and flower style length. C. pepo genotypes possessed the shorter pollen tubes (480.73 to 625.61 μm) and style length (12.00 to 14.00 cm) in comparison to larger pollen tubes (603.32 to 1588.18 μm) and style length (12.50 to 20.00 mm) of C. moschata, which accounted the failure of interspecific crosses. The fertilization of larger style length genotypes of C. moschata with shorter pollen tubes of C. pepo resulted the limited success in hybridization, whereas the reciprocal crosses were more successful. In addition, the pollen tube and flower style length were positively and significantly correlated with each other (r= 0.918), suggesting that these might be the major contributing factors involved in the present hybridization study. These findings provide new insights for the development of methods to overcome reproductive barriers.