Timing and Rate of Ethephon Application to Two‐Row and Six‐Row Spring Barley

Abstract

Ethephon (2‐chloroethyl phosphonic acid) reduces lodging in barley (Hordeum vulgare L.) by shortening straw, but the optimal rate and growth stage of application, both of which may interact with cultivar and environment, are unclear, especially for two‐row barley in North America. Field studies in Quebec in 1985 and 1986 evaluated the response of ‘Leger’ six‐row and ‘Birka’ two‐row barley to ethephon applied at varying rates, growth stages, and times of day. The two‐row cultivars Rodeo and Micmac were also included in one experiment. Lodging was slight or absent in all experiments. The taller Leger was usually shortened more than Birka, largely due to greater shortening of the peduncle. Late boot applications of ethephon consistently shortened straw, but the window of effective application began at the flag leaf stage and extended for more than 1 wk for Birka, while for Leger it was about 4 d, but differed phenologically between years. Heading was delayed by ethephon. In Rodeo and Birka, ethephon often reduced the degree of spike emergence from the flag leaf sheath. Incomplete spike emergence may have contributed to reduced kernel and test weights, particularly with applications from the flag leaf until the late boot stage. Ethephon increased Leger yield by up to 15% in one experiment under the favorable conditions of 1985. In 1986, a wet year, yield in one experiment was reduced by 11% by the higher ethephon rate (480 g a.i. ha−1), due to reduced spikes per square meter. Birka yield was reduced (P = 0.06) by 6% by the higher rate (480 g a.i. ha−1) in the 1986 application date study. Harvest index of Rodeo and Birka was reduced due to reduced tiller survival following application of ethephon at 480 to 500 g a.i. ha−1. Yield component compensation usually occurred between spikes per square meter and kernel weight, particularly for two‐row cultivars. Height was reduced more by applications at 0400 h and 0600 h than later in the day. Birka kernel weight was reduced with morning or evening applications, while Leger kernel weight was little affected by application time of day. In the absence of lodging and under conditions of environmental stress, ethephon applied at rates over 240 g a.i. ha−1 may reduce yields, particularly of two‐row barley, for which spike emergence may be severely reduced.

Validating FAO AquaCrop using Landsat images and regional crop information

“…Earlier studies suggested various HI values ranging from 0.4 to 0.6 for maize and barley (e.g. Kiniry et al, 1997;Bridger et al, 1995), but it is not easy to identify a suitable value for a given study area. The value depends on many factors such as cultivars and management practices.…”

Net Primary Production of U.S. Midwest Croplands From Agricultural Harvest Yield Data

“…In the breeding experiment of Boukerrou and Rasmusson (1990), the mean HI for commonly grown cultivars was 0.48. Bridger et al (1995) performed an experiment in preventing lodging with the application of ethephon and found a mean HI of 0.48 for controls to which no ethephon was applied. Bridger et al (1995) performed an experiment in preventing lodging with the application of ethephon and found a mean HI of 0.48 for controls to which no ethephon was applied.…”

“…Jedel and Helm (1994) examined the agronomic traits of barley in western Canada and found a HI of 0.52 for six-rowed cultivars and 0.50 for two-rowed cultivars. Bridger et al (1995) performed an experiment in preventing lodging with the application of ethephon and found a mean HI of 0.48 for controls to which no ethephon was applied. Nedel et al (1993) obtained a mean HI of 0.52 in a study of the effects of nitrogen fertilization on barley yield and malting quality, at nitrogen application rates up of 60 kg/ha.…”

Barley: Physiology of Yield

“…Ethephon treatment can result in a reduced barley harvest index. While ethephon reduces lodging, it also results in incomplete spike emergence and reduced tiller survival and, consequently, reduced grain weights (Bridger et al 1995). Harvest index is influenced by interactions among rainfall patterns, N fertilization and grain-filling temperature (Gonzales-Ponce et al 1992).…”

“…Harvest index and yield were shown to decrease with increased water deficit (Salam et al 1991), saline irrigation (Ahmed et al 1993) and interference by quackgrass (Pageau and Tremblay 1995). Decreased yield generally occurs where harvest index is reduced (Bridger et al 1995). However, growing conditions may be such that yield and total biomass production are increased but harvest index is reduced (Jedel and Helm 1992).…”