Effects of 2-chloroethylphosphonic acid on fruit set and subsequent development in Prunus salicina

A study to determine the effects of Ethrel on fruit set and the subsequent development of Prunus salacina was conducted on the cultivars Late Santa Rosa and Nubians. The results of the study showed 75, 150, and 300 ppm Ethrel effectively reduced the fruit set in Late Santa Rosa when applied at 5-, 8-, and 12-nun ovule length. In Nubiana, 300 ppm Ethrel reduced the fruit set of 6, 9, and 11 mm ovule length fruits, but the 75 and 150 ppm rates were only effective on the 6-ram ovule length fruits. The wheat coleoptile straight-growth test was used to determine the effects of Ethrel on endogenous auxins and inhibitors. Both developing and abscissing Ethrel-treated fruits attained higher levels of auxin activity than did their respective controls. It is suggested that such an accumulation is brought about by an ethylene induced inhibition of auxin transport. The mode of action of such a system is discussed.