Effects of Jasmonic Acid and Ethephon on Tillering to Maturity in Spring Barley

Spring barley cultivated in Mitcherlich pots under both climaticchamber and field conditions were treated at developmental stageFeekes 2 with a foliar application of jasmonic acid (JA), itsmethyl ester (JAMe) and ethephon. Tillering was determined atFeekes 5 by counting all emerged tillers. The number of ear-bearingtillers, yield, and shoot length were ascertained at harvest.A combination of either JA or JAMe together with ethephon, appliedsimultaneously or successively (within 24 h), led to a significantincrease in tiller production. However, the additional tillerswere not sustained to maturity. Neither JA or JAMe nor ethephonalone were able to cause these effects at Feekes 2. JA seemsto increase the sensitivity to ethylene, possibly by influencingthe level of other native regulators. The JA/ethephon applicationat Feekes 2 did not affect the yield and the final shoot length. Spring barley, Hordeum vulgare L., tillering, apical dominance, plant growth regulators, ethephon, jasmonic acid