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

Spring barley cultivated in Mitcherlich pots under both climatic chamber and field conditions were treated at developmental stage Feekes 2 with a foliar application of jasmonic acid (JA), its methyl ester (JAMe) and ethephon. Tillering was determined at Feekes 5 by counting all emerged tillers. The number of ear-bearing tillers, yield, and shoot length were ascertained at harvest. A combination of either JA or JAMe together with ethephon, applied simultaneously or successively (within 24 h), led to a significant increase in tiller production. However, the additional tillers were not sustained to maturity. Neither JA or JAMe nor ethephon alone were able to cause these effects at Feekes 2. JA seems to increase the sensitivity to ethylene, possibly by influencing the level of other native regulators. The JA/ethephon application at Feekes 2 did not affect the yield and the final shoot length.