Effects of Physical Treatments on Breaking of Seed Dormancy in Thai Cucumber

Abstract

The effects of various physical treatments and fruit incubation under ventilated ambient temperature for 5 or 7 days on the breaking of the seed dormancy of the local Thai cucumber varieties, ‘Puang’ and ‘Jed-Bai’ were investigated. The sun exposure and 9-day continuous hotair treatments (40°C) were effective in the breaking of the seed dormancy and improvement of seed germination rates and seed vigor in ‘Puang’, whereas the hot air and accelerated aging (45°C 100% RH. for 2 days) treatments increased the germination rates and seed vigor in ‘Jed-Bai’. Before the physical treatments were applied, fruit incubation did not improve seed germination, although it increased the GAs contents in seeds. In general, fruit incubation did not affect the influence of the treatments on dormancy. The analysis of GAs, ABA and cytokinins in seeds suggested that the sensitivity to ABA was different in the two varieties used and that some unknown germination inhibitory factors other than ABA played an important role in the dormancy of the local Thai cucumber varieties.