The present study was carried out at Mallawi Agric. Res. Station, Minia, in
2001 and 2002 seasons to study the effect of foliar application of ethrel (ethephon) in
low concentrations (0, 10, 20 and 40 ppm) at squaring stage or at early flowering
stage on late sown cotton plants of Giza 83 cultivar. The obtained results showed that, in comparison with the control, ethrel
tended to decrease plant height, leaves content of chlorophyll and number of days to
first open boll with increasing the reduction in Ihese traits as ethrel concentration
increased. On the other hand, aU ethrel concentrations, In generat, increased leaves
content of sugars, number of sympodla, flowers, and open bolls per plant, boll
relenlion%, ear1iness%. and seed colton yield per faddan, however, all of these traits
were significantly increased over the control only by 10 or 20 ppm which gave Ihe
highest yield and the best results in general. Fiber properties were not affected by
ethrel treatments.   Both time of application and the interaction between time of application and
elhrel concsntration had almost no rnarxed affects on plant growth and yield. It could be concluded that treatment of late sown cotton plants with 10 or 20
ppm of ethrel at either squaring stage or early flowering stage improved the plant
fruiting performance and yield under lale planting conditions.