RESPONSE OF BARLEY TO ETHEPHON - EFFECTS OF RATE, NITROGEN, AND IRRIGATION

Lodging incidence in cereal crops depends upon both crop management and environmental conditions. Ethephon [(2-chloroethyl) phosphonic acid] controls lodging, thus preserving yield. The objective of this study was to investigate the effects of ethephon on spring barley (Hordeum vulgare L.) with different N rates, irrigation treatments, or application rates of ethephon. Ethephon was applied at Zadoks Growth Stage 43 at 0.28 kg ha-1 in the N and irrigation studies, and at rates between 0.1 and 0.5 kg ha-1 in the ethephon rate study. Plant height and lodging were reduced by ethephon in each study; however, ethephon did not consistently reduce lodging at Belgian indices of 7.0 and above. Differences in cultivar response were observed. In the ethephon rate trial, 0.1 kg ha-1 ethephon reduced lodging of 'Harrington', while 0.25 kg ha-1 was required to similarly reduce lodging of 'Leduc'. Ethephon reduced the number of kernels per spike, had variable effects on grain mass, and delayed crop maturity by up to 4 d. Whole plant protein was unaffected by ethephon. Ethephon reduced grain protein by 3% and increased straw protein by 11% in 1985, increased grain protein by 25% and decreased straw protein by 9% in 1986, and had no effect on grain protein in 1987. Ethephon was an effective antilodging agent only under moderate lodging pressures; it is not likely to preserve an increased yield under conditions of intense irrigation and high fertility.