Yield and Grain Protein Response of Spring Barley to Ethephon and Triadimefon

Abstract

Barley (Hordeum vulgare L.) is used principally as a feed crop in Québec. Consequently, a high protein concentration in the grain is desirable. A 2‐yr field study was conducted to study the effects of ethephon [(2‐chloroethyl)phosphonic acid] and a late application of triadimefon [l‐(4‐chlorophenoxy)‐3,3‐dimethyl‐1‐(1H‐l,2,4‐triazol‐1yl)‐2‐butanone] on yield and grain protein concentration (GPC) of three cultivars of spring barley. Recommended rates of ethephon were applied at booting, and of triadimefon at heading. Ethephon consistently reduced plant height, and reduced lodging when lodging occurred in control plots. Ethephon and triadimefon effects on yield and GPC were inconsistent. In 1987 triadimefon applied in the absence of ethephon increased the yield of Cadette 22%. Ethephon increased yield of Leger 24%, and decreased yield of Argyle 19%. Increased spikelet sterility at the distal end of main stem spikes was responsible for the yield reductions in Argyle. Ethephon and triadimefon had no significant effect on yield in 1988. Ethephon could alter GPC by reducing the nonprotein dry matter component of the grain, by increasing protein per grain, or by altering the distribution of grain sizes in harvested samples. In 1987 ethephon significantly decreased total and nonprotein dry matter per grain for Argyle, but increased protein per grain, and consequently, GPC. In 1988, ethephon reduced nonprotein dry matter per grain in Cadette and Argyle. With Argyle, both total dry matter per grain and protein per grain were reduced so that GPC was not significantly affected. The results show that ethephon can influence GPC by altering the protein and nonprotein components of the grain.