AGRONOMIC AND ECONOMIC RESPONSE OF SPRING WHEAT CULTIVARS TO ETHEPHON

Efforts to optimize grain yields in wheat (Triticum aestivum L.) are often hindered by excessive lodging associated with intensive cereal management systems. The plant growth regulator ethephon [(2-chloroethyl) phosphonic acid] has been used as an essential component of intensive cereal management systems in Europe to control lodging and maintain high yield potential. The objective of this study was to determine the effect of ethephon on four hard red spring wheat cultivars in North Dakota environments. A randomized complete block design in a split plot arrangement with four replicates was used at each of four locations in 1987 and 1988. Main plot treatments consisted of the cultivars Era, Stoa, Len, and Nordic, and split plots were assigned to ethephon and control (no ethephon). Application of ethephon (280 g a.i. ha-1) increased grain yield 5.4% when averaged across environments and cultivars. Generally, ethephon application tended to increase spikes per square meter but had no effect on kernel weight and kernels per spike. Ethephon treatment reduced lodging in 1987. Lodging was absent in 1988. Application of ethephon had a significant positive effect on test weight, but did not influence grain protein concentration and maturity. Economic parameters, net benefit, and marginal rate of return, indicated ethephon could be recommended for cultivars Era, Len, and Stoa, but not for Nordic under environmental conditions similar to those in this study.