Growth and Yield of Winter Wheat as Influenced by Chlormequat Chloride and Ethephon
Lodging can be a constraint in wheat (Triticum aestivum L.) production, therefore interest exists for use of plant growth regulators (PGRs) such as Chlormequat chloride or CCC (2-Chloroethyl-N, N, N-trimethylammonium chloride) and ethephon [(2-Chloroethyl) phosphonic acid] for lodging control. Field experiments were conducted in New York in 1985 and 1986 on a Honeoye silt loam (fine-loamy, mixed mesic Glossoboric Hapludalfs) to examine the influence of CCC (1.37 kg ha−1 a.i. at Zadoks Growth Stage (GS) 31) and ethephon (0.40 kg ha−1 a.i. at GS 39) on vegetative and reproductive growth of two winter wheat cultivars, Geneva and Houser. Leaf, stem, and spike phytomass were determined at 10-d intervals from GS 25 to 95, and kernel number and weight were determined on 15 main-culm spikes at 3 to 4-d intervals during the grain-filling period. The CCC application reduced culm and total phytomass by 9% at GS 45, whereas ethephon reduced spike and total phytomass by 10 and 8% at GS 55 and GS 75, respectively. Neither PGR had an effect on total or component phytomass at harvest. In 1985, a year when no lodging occurred, ethephon and CCC yielded the same compared with the yield of the check (6.12, 6.60, and 6.39 Mg ha−1, respectively). In 1986, a year of considerable lodging, ethephon reduced lodging compared with that of CCC and the check, which was reflected in a higher kernel growth rate (1.00, 0.84, and 0.81 mg kernel−1 day−1), kernel weight (43.4, 39.8, and 38.9 mg), and grain yield 5.73, 4.71, and 5.30 Mg ha−1, respectively) in the more lodging-susceptible cultivar, Houser. The data indicate that, under the environmental conditions of this study, CCC does not benefit wheat and that ethephon should be utilized only under severe lodging conditions.
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