Impact of grain morphology and genotype by environment interactions on test weight of spring and winter wheat (Triticum aestivum L.)

Authors: YABWALO, DALITSO - South Dakota State University; BERZONSKY, WILLIAM - Bayer Cropscience; Brabec, Daniel - Dan; PEARSON, THOMAS - Amgen, Inc; GLOVER, KARL - South Dakota State University; KLEINJAN, JOHATHAN - South Dakota State University

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2018
Publication Date: 7/2/2018
Citation: Yabwalo, D.N., Berzonsky, W.A., Brabec, D.L., Pearson, T., Glover, K.D., Kleinjan, J. 2018. Impact of grain morphology and genotype by environment interactions on test weight of spring and winter wheat (Triticum aestivum L.). Euphytica. 214:125. https://doi.org/10.1007/s10681-018-2202-7.
DOI: https://doi.org/10.1007/s10681-018-2202-7

Interpretive Summary: Wheat grades and grain prices are determined in part by test weight which is a basic physical measurement relating to the apparent density of the wheat. Flour millers value wheat that has high test weight, because it is typically associated with higher flour extraction rates and increased end-use quality. In this study the primary morphological grain traits that contribute to test weight in both hard winter and hard spring wheat classes were evaluated. These traits included seed-length, seed-width, image-area, thousand kernel weight, seed density, and many ratios of the basic parameters. The wheat samples include 24 hard winter wheat and 32 hard spring wheat cultivars which were grown at 8 locations for winter wheat and 5 locations for spring wheat over two seasons in South Dakota. Seed density was shown to be the trait that accounted for most of the variation in the expression of test weight in both wheat classes. Although, the test weight of wheat in both classes was significantly impacted by environmental factors such as growing season and location. For instance the hrw wheat Robidoux average 55.2 lb/bu in the first season and 60.1 lb/bu in second season across the eight growing locations. The relationship of seed density with test weight was strong enough that it could be used by wheat breeders as a secondary trait to indentify wheat cultivars with high test weight to develop new varieties. Seed density is amenable to rapid methods and only requires a few hundred seeds. This method could be useful to breeders because little is known about the underlying genetic basis of seed density and test weight, which makes the use of molecular markers problematic at the moment.

Technical Abstract: Wheat (Triticum aestivum L.) market grades and grain prices are determined in part by test weight (TW). Millers value high TW, because it is typically associated with higher flour extraction rates and increased end-use quality. Test weight is expected to be influenced by other directly measurable grain attributes such as; grain length, width, shape, single-grain-density (SGD), thousand-grain-weight (TGW) and packing efficiency (PE). The objectives of this study were to; (i) determine the primary morphological grain attributes that contribute to TW in both winter and spring wheat classes; and (ii) determine stability and the genotype (G), and the genotype x environment interactions (GEI) of the attributes that contribute to TW. A market class representative group of 24 hard winter wheat and 32 hard spring wheat cultivars were grown at several locations in South Dakota in 2011 and 2012. Regularized regression was used to develop a TW model. A GGE biplot was used for stability analyses; whereas, a linear mixed model was used for variance analyses. Data were collected on 8 grain traits: TW, SGD, TGW, protein content, single grain width (GW), length (GL), shape, size, and PE. Regularized multiple regression methods were used to determine what grain attributes can reliably predict TW. Observations showed that in both spring and winter wheat SGD accounted for over 90% of the phenotypic variation of TW. Stable and high TW genotypes were identified in both wheat market classes. Apart from TW, significant (p<.0001) genotype, environment and GEI variances were observed for SGD and GW.