Internal ethylene of attached fruit of ‘Starkspur Golden Delicious’ apple as influenced by 6 rootstocks: Seedling, Mailing (M1) 1, Mailing Merton 106 (MM 106), M 7, OAR 1, M 26, at 2 levels each of soil-applied K and N were measured during maturation for 2 years (1980 and 1981). Ethylene evolution of detached fruit as a result of these treatments also was measured after 2.5 months of storage at 0°C in 1981. Internal ethylene in the attached fruit was less than 0.1 μl·liter-1 in late September and early October and began to rise between 9 Oct. and 15 Oct. Internal ethylene increased in all treatments, almost at the same time in 1980. In 1981, ethylene in the fruit on OAR 1 began to increase 9 days later than in the other rootstocks. However, levels of ethylene in the fruit were relatively low on OAR 1 and high on M 26 as compared to those on other rootstocks in late October 1980 and 1981 and during poststorage 1981 samplings. Ethylene levels in fruit from other rootstocks were similar. Because of these variable effects of rootstocks, and the effects of a low field temperature in reducing internal ethylene levels, field sampling of internal ethylene levels was an unreliable indicator of the proper harvest time, as measured by other maturity indices. No consistent influence of K or N applications was found in the internal ethylene of the attached fruit; however, high N applications increased ethylene evolution after storage.
Postdoctoral Research Associate.
National Technical Advisor for Clonal Germplasm.
Received for publication 16 Mar. 1984. Technical paper no. 7116 of the Oregon Agr. Expt. Sta. Part of the PhD thesis of the senior author. Technical assistance of Bahar Fallahi is gratefully appreciated. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.