Stability analysis of stem solidness, grain yield, and grain protein concentration in spring wheat

Abstract

The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of wheat (Triticum aestivum L.) in the northern Great Plains where it is a constant threat in Montana and is resurging in Alberta, Saskatchewan and North Dakota. Adoption of solid-stemmed cultivars is an important management tool for wheat growers; however, the inconsistent pith expression first noted with the release of ‘Rescue’ has been repeatedly observed in modern cultivars such as ‘Lillian’ in Canada. Given the extensive hectares planted to solid-stemmed wheat cultivars during an outbreak, identification of cultivars that display stable stem solidness, grain yield and grain protein concentration across a wide range of environments where stem sawfly infestations occur is desirable. We assessed spring wheat plant responses in eight solid-stemmed and two hollow-stemmed genotypes grown across diverse environments using multiple statistical models. Study sites included southern Alberta and Saskatchewan, Montana and North Dakota. Most models agreed that the genotypes, ‘Choteau’ ‘BW925’ and ‘Mott’ consistently displayed high and stable stem solidness concomitant with high grain yield. ‘Choteau’ and ‘BW925’ also consistently met or exceeded the desired threshold of a 3.75/5 pith rating (averaged from the lower four stem internodes) for optimum resistance whereas, ‘Mott’ developed optimal pith at a specific (early) phenological stage when resistance to WSS infestation is critical. Exploring stability of stem solidness identified ideal genotypes that would enhance germplasm development efforts, which exemplifies how this approach can facilitate the selection, production, and adoption of solid-stemmed wheat cultivars in regions prone to WSS attack.

Estimation of Stem-Solidness and Yield Components in Selected Spring Wheat Genotypes

“…These were two solid-stemmed genotypes (AC Eatonia, Rescue), two hollow-stemmed genotypes (Bombona and Łagwa), and one cultivar with intermediately filled stems (401). The stability of the AC Eatonia genotype was confirmed in a study by Subedi et al [26].…”

“…For example, the solid-stemmed Lillian cultivar, which is commonly grown in Canada due to its resistance to wheat stem sawflies, high yield and high protein content in seeds [17,24] did not exhibit a strong expression of this trait in Poland and was classified into the group with stems intermediately filled with pith. Subedi et al [26] also noted the inconsistent pith expression in this cultivar.…”

Evaluation of wheat stem sawfly‐resistant solid stem Qss.msub‐3BL alleles in hard red winter wheat

“…However, winter wheat experiences greater exposure to peak WSS emergence than spring wheat. WSS emergence and oviposition activity can begin as early as mid‐May and continue until mid‐July (Buteler et al., 2015; Morrill & Kushnak, 1996; Subedi et al., 2021). In winter wheat, the peak WSS activity is concurrent with stem elongation to anthesis period; however, a substantial number of WSS continue to emerge post winter wheat anthesis (Varella et al., 2016).…”

QTL analysis identified two major all-internodes solidness loci from a completely solid-stemmed spring wheat line

“…Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), imposes severe economic barriers to wheat ( Triticum aestivum L.) production in the northern great plains of North America and many other wheat-producing regions around the globe ( Morrill et al., 1992 ; Talbert et al., 2014 ). WSS females deposit eggs in hollow stems soon after emergence from the infested stubble of the previous year’s crop following mating, usually in the early crop growing season ( Beres et al., 2011a ; Talbert et al., 2014 ; Subedi et al., 2020 ). These eggs hatch within 5–7 d of deposition and the resulting larvae begins feeding upon the vascular bundle tissues within the stalk ( Ainslie, 1929 ).…”

“…Larvae feed on the vascular bundles, make tunnel across internodes in the stem, interfere with the stem storage and transfer of water and nutrients to the developing grains, and reduce photosynthesis and grain yield ( Macedo et al., 2007 ). In recent years, WSS has not only expanded its infestation area outside its traditional territories ( Lesieur et al., 2016 ) but has also become a constant economically challenging insect pest in North America ( Subedi et al., 2020 ). WSS-infested plants showed 5–30% kernel weight reductions in field and greenhouse conditions ( Wallace et al., 1973 ; Delaney et al., 2010 ).…”