EFFECT OF 2 PLANT-GROWTH REGULATORS ON THE YIELD AND QUALITY OF BURBANK,RUSSET POTATOES

Foliar applications of ethephon (ETH) 300 g a.i. ha-1; chlormequat chloride (CCC) 920 g a.i. ha-1, with a second application of 230 g a.i. ha-1 approximately 2 weeks later; and a mixture of the two (ETH/CCC) 156 g a.i. ethephon and 299 g a.i. chlormequat chloride ha-1 were made to field-grown Russet Burbank potatoes in 1986, 1987 and 1989. All the treatments increased the number of tubers set and reduced the average tuber weight compared to the control, resulting in a reduction in premium and marketable tubers, and an increase in small tubers. Differences were greatest for ETH and least for CCC. ETH and ETH/CCC decreased the specific gravity, increased the incidence of deformities, and decreased the incidence of tubers with hollow heart. The growth regulators did not affect fry colour.