Effect of different physio-chemical factors on sex expression and fruit yield in green-house cucumber

Male flower expression is considered an important aim in greenhouse cucumber breeding for creating paternal lines as a base for hybrid progeny. The study was carried out to evaluate the effects of different treatments on sex expression and fruit yield of cucumber in two different season (autumn-winter and spring-summer), in particular this research focuses on the influence of 1) usage of two chemical agents: silver thiosulphate [Ag(S2O3)2-3] and silver nitrate (AgNO3) at different concentration, respectively 200 and 500 ppm and 100, 200 and 300 ppm 2) plant development stages at the moment of the treatment (5, 10, and 15-leaf growth stages) and 3) application of single or double sprayings. Analysis of variance showed that season, chemical applications and number of spaying had significant effect on the induction of a higher number of male flowers. A positive significant effect of season suggested that longer days and higher temperature promote the formation of male flowers in cucumber. This study showed that male flower production was induced by all concentrations of silver ions, especially high concentrations. Important traits related to change of sex expression such as the number of days to male flowering and the number of male flowers are more affected by different interactions of studied factors in contrast to vegetative and yield related traits. Also, the quadruple interaction effects indicated that silver ion could change sex expression at  higher temperatures and longer days (second season in summer) with high concentration when applied in 15 leaf stage for AgNO3 and 5 and 15 leaf growth stage for Ag(S2O3)2-3 with double spraying. Consequently, female lines can be induced to male flowering with silver ions, thus increasing the feasibility of large scale seed production of gynoecious × gynoecious cucumber hybrid.