Environmental Effects on Developing Wheat as Sensed by Near-Infrared Reflectance of Mature Grains

Cereal Chem. 79(6):885-89\ For 30 yean,. near-infrared (NIR) spectrmcopy has routinely heen applied to the cereal grains for the purpose of rapidly measuring concentrations of constituents such as protein and moisture. The research descrihed herein examined the ability of NIR reflectance spectroscopy on harvested \!; heat to determine weather-related, quality-determining properties that occurred during plant development. Twenty commercial cultivars or advanced breeding lines of hard red winter and hard white wheat (Triticum aestivum L.) were grown in \0 geographical locations under prevailing natural conditions of the U.S. Great Plains. Diffuse reflectance spectra (l, I 00-2,498 nm) of ground wheat from these samplcs were modeled by partial least squares one (PLS \ ) and multiple linear regression algorithms for the following properties: SDS sedimentation volume, amount of time during grain fill in which the temperature or relative humidity exceeded or was less than a threshold level (i.e., >30, >32. >35. <24°C; >80'7c, <40o/r rh). Rainfall values associated with four preand post-planting stages also Despite considerable effort in research on the genetic basis of wheat (Triticum aestinlln L.) quality (often defined by dough properties). the role of environment or seasonal variation has been much less studied and. conscquently. is less understood. Whereas wheat quality is partially determined by genetics (hence the rcliance on cultivar specification in many wheat-prcxlucing countries). cultural environment and its interaction with genotype can also detem1ine quality (Busch et al 1969). In the United States, the environmental etTect is often larger than the genetic effect on wheat quality (Peterson et al 1992). Sueh effects may include soil type, fertilizer level (especially N or S [Paredez-Lopez et al 1985; Mac Ritchie and Gupta 1993; Daniel and Triboi 2000; Luo et al 2000j). distribution of rainfall level (Faridi and Finlay 1989). and late season frosts (Lookhart and Finney 1984). In certain regions. elevated temperature during grain filling is possibly the most important environmental detenninant of grain quality (Randall and Moss 1990). It is believed that high temperatures during grain filling, especially >35°C, alter the protein biosynthetic pathways of grain. leading to protein compositional changes (Blumenthal et al 1993). This temperature is particularly significant in light of wheat's general adaptation to moderate climates. such that the gradual increa<;e in worldwide temperature from global wanning may cause severe limitations for wheat cultivation (Ciaffi et al 1996). In a recent report by Blumenthal et al (1998), four hypotheses were proposed to account for changes in dough strength that are caused by heat stress: I) changes in the ratio of glutenin to gliadin: 2) alteration in the fonnation of disulphide bonds between glutenin peptides, thus leading to a reduction of the size of the glutenin polymers: 3) the direct elleds of heat-shock proteins on dough strength; and 4) changes that heat-shock proteins and chaperones impose on the folding and polymerization of I USDA! ARS. Belbville Agricultural Research Center. Instrumentation and Sensing Laboratory. Beltsv~le. \1D 20705-2:150. Names are necc"ary to report factually on available data: however. the USDA neither guarantees nor warrants the standard of the product. and the use of the name hy the eSDA implies no approval of the product to the exclusion of others that may also be suitable. 2 Corresponding author. E-mail: [email protected]"da.go\. 3 Department of Agronomy and Horticulture. Cniversity of "lebraska. Lincoln. NE. 4 USDAJARS at Department of Agronomy and Horticulture. Cnive"ity of Nehraska.