The effect of ethephon seed treatment on leaf development and head initiation of wheat

The ability to control the transition from vegetative to reproductive growth could potentially increase wheat yields, particularly in regions subject to midseason drought stress. Little is known about the factors that regulate or affect this transition in wheat and other graminae. Because ethephon is known to accelerate this transition in other plants, the effect of seed treatment on spring wheat growth and development was investigated. Seedlings derived from seeds imbibed in ethephon underwent the transition from vegetative to reproductive growth earlier than seeds imbibed in water. The percentage of 17-day-old plants with four fully-emerged leaves (i.e., plants in which meristem development had proceeded from vegetative apex to double-ridge formation) showed a positive correlation with ethephon concentration. Subsequent yield components were unaffected with the exception of a small increase in the number of kernels/spike in plants derived from seeds imbibed in ethephon solutions for 24 h. Neither root nor shoot dry weights of 21-day-old plants were affected by the treatments. Germination percentages were unaffected by the treatments but 8-day-old plants derived from seeds imbibed for 24 h had reduced height with increasing ethephon concentrations. These results will be useful in further studies of the biochemical basis of the transition to reproductive growth.