Intensive Crop Management Practices on Wheat Yield and Quality

Some researchers have reported increased wheat (Triticum aestivum L.) yields with increased N levels, narrow row spacings (R), and applications of plant growth regulators (PGR) and fungicides (F). However, little information is available concerning the effects of these factors and their interactions on irrigated wheat production in California. Therefore, this study was conducted in the eastern San Joaquin Valley of California at two locations (Dinuba and Fresno) with two planting dates (mid-December 1986, and late January 1987) to determine the effects of three N levels (168, 220, and 252 kg ha⁻¹), PGR ethephon [Ethephon (2-chloroethyl) phosphonic acid], and F triadimefon [1-(4-Chlorophenoxy)-3,3-dimethy-1-(lH-1,2,4-triazol-l-yl)-2-butanone] applied to the semidwarf, hard red spring wheat cultivar Yecora Rojo planted at 10- and 17-cm-row spacings. Early planting increased grain yield, but no other variables affected grain yield or grain protein content. Yield and protein were not increased with N rates above the lowest rate, 168 kg ha⁻¹, Lodging was increased with increasing amounts of applied N, except for the second planting date at Fresno. Applications of PGR reduced lodging but did not effect yield or grain protein, even at increased N levels. A lack of foliar disease resulted in no benefits from F applications. No notable interactions were observed between the different treatments on grain yield, but PGR interacting with other variables generally reduced stem base NO₃−N. Intensification of cultural practices was not effective for increasing grain yield and grain protein content in this region with the environmental conditions experienced. This may be due to the already optimized cultural practices used in the region. Research supported in part by grants and support from the California Wheat Commission, Union Carbide Corp., Mobay Corp., and Germain's Inc.¹ California Agric. Technol. Inst. Tech. Pap. no. 900703.