Abstract

Hidayat Ullah, Asghari Bano, K. M. Khokhar and T. Mahmood

Field experiments were undertaken at national agricultural research centre Islamabad, Pakistan during
2004 and 2005 to study the seed soaking effects of 2-chloroethylphosphonic acid (ethrel), gibberellic
acid and maleic hydrazide (MH) on sex modification in cucumber and to find out the critical
phytohormones level of endogenous hormones for lowest sex ratio. Seeds were soaked in different
concentrations of growth regulators for 20 h prior to sowing. Seed soaking with MH at 450 ???mol/L
highly increased the number of pistillate flowers and fruit yield per plant and decreased the sex ratio
compared to that of untreated control. The phytohormone levels of indole acetic acid (IAA) at blooming
and fruiting stages were significantly higher with MH at 450 µmol/L and had a positive significant
correlation with the number of pistillate flower/plant and negative correlation with sex ratio. Fruit yield
had also a positive significant correlation with endogenous IAA. Ethrel also significantly lowered the
male to female sex ratio in cucumber.