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Two drought-tolerant wheat cultivars, 'TAM 111' and 'TAM 112', have been widely grown in the Southern Great Plains of the U.S. and used as parents in many wheat breeding programs worldwide. This study aimed to reveal genetic control of yield and yield components in the two cultivars under both dryland and irrigated conditions. A mapping population containing 124 F5:7 recombinant inbred lines (RILs) was developed from the cross of TAM 112/TAM 111. A set of 5,948 SNPs from the wheat 90K iSelect array and double digest restriction-site associated DNA sequencing was used to construct high-density genetic maps. Data for yield and yield components were obtained from 11 environments. QTL analyses were performed based on 11 individual environments, across all environments, within and across mega-environments. Thirty-six unique consistent QTL regions were distributed on 13 chromosomes including 1A, 1B, 1D, 2A, 2D, 3D, 4B, 4D, 6A, 6B, 6D, 7B, and 7D. Ten unique QTL with pleiotropic effects were identified on four chromosomes and eight were in common with the consistent QTL. These QTL increased dry biomass grain yield by 16.3 g m-2, plot yield by 28.1 g m-2, kernels spike-1 by 0.7, spikes m-2 by 14.8, thousand kernel weight by 0.9 g with favorable alleles from either parent. TAM 112 alleles mainly increased spikes m-2 and thousand kernel weight while TMA 111 alleles increased kernels spike-1, harvest index and grain yield. The saturated genetic map and markers linked to significant QTL from this study will be very useful in developing high throughput genotyping markers for tracking the desirable haplotypes of these important yield-related traits in popular parental cultivars. [ABSTRACT FROM AUTHOR]

For hybrid wheat (Triticum aestivum L.) to be successful in the Great Plains, good‐quality hybrid seed production must be reliable, and hybrid yield must exceed best commercial inbred cultivars (commercial heterosis). This research evaluates hybrid wheat cultivars developed from a full diallel of 26 parents that were planted in an augmented design at three locations in Nebraska in each of two years. The effects of using chemical hybridization were evaluated by testing the parents against hybrids that were created as full‐sib crosses and showed no detrimental effects of the chemical hybridization method on the hybrid performance. Maternal effects were tested by comparing the reciprocals for each combination of parents, where it was shown that reciprocal effects were of minor importance. General and specific combining abilities and narrow‐sense heritability were obtained and are being used to select parents for future hybrid combinations. [ABSTRACT FROM AUTHOR]

In the U.S. Great Plains and other parts of the world, Wheat streak mosaic virus (WSMV) disease is one of the most important biotic stresses affecting wheat (Triticum aestivum L.) productivity. Breeding for wheat cultivars with resistance provides a socioeconomic and environmentally sustainable approach for combating WSMV. The use of markers as a proxy for quantitative and qualitative traits is widely applied in crop improvement programs. Among the available markers, single nucleotide polymorphisms (SNPs) are routinely used in plant breeding programs to distinguish potentially superior genotypes with genetic merit for traits of interest. In this study, we used the 90K Illumina Infinium iSelect SNP assay to tag the Wsm2 gene in a set of 152 recombinant inbred lines (RILs) derived from the cross between CO960293–2 and TAM 111. The RILs were evaluated twice for WSMV resistance in the growth chambers. A dense linkage map with coverage of 2079.5 cM was constructed. The Wsm2 gene was mapped on chromosome 3BS. A total of eight SNPs flanking Wsm2 were mapped within 1.0 cM. These tightly linked SNPs could be useful for marker-assisted selection for WSMV resistance. [ABSTRACT FROM AUTHOR]

Water supply and distribution are the main limiting factors to wheat (Triticum aestivum) yield in a semi-arid region of the U.S. southern Great Plains. To manage crop water demand, limited irrigation (also called deficit irrigation) is commonly practiced in the region. A 4-yr study was conducted to evaluate yield in winter wheat cultivars as influenced by the depth and amount of net soil water extraction (SWE) under limited irrigation. For timing the irrigation application, we considered critical growth stages (jointing, tillering, and anthesis) as well as soil water depletion at the crop root zone below 50%. Volumetric soil water content was measured in 0.2 m increments to the depth of 2.4 m at planting, jointing, anthesis, and physiological maturity. Since the irrigation capacity was limited, seasonal precipitation was still an important factor for determining SWE. The 2011 season was one of the historic drought seasons with only 60 mm of seasonal precipitation and the net SWE in that season was limited to the upper 1.2 m profile. In contrast, the 2016 season was more favorable for crop growth with 315 mm of seasonal precipitation and the net SWE in that season reached to 2.0 m deep. Grain yield was largely influenced by the amount of net SWE during the growing season. For the wheat with grain yield of 4807 kg ha−1, net SWE was 165 mm (2016). However, wheat with grain yield of 2933 kg ha−1 only extracted 70 mm stored soil water (2011). The 2012 and 2017 seasons remained intermediate in terms of seasonal precipitation, SWE, and yield. Although the 2011 and 2016 seasons had similar stored soil moisture at planting, more early-season as well as total precipitation in 2016 appears to have enabled plant growth to access the deeper water. In contrast, a greater amount of stored soil water was left unused at the end of the 2011 season due to drought and poor plant growth. Hence, in addition to adding water at critical growth stages, ensuring early plant growth to promote root development for extracting soil water from the deeper profile later in the season should be a key strategy to take full advantage of limited irrigation. • A 4-yr wheat field study was conducted under limited irrigation. • More precipitation helped plants to grow and extract water from deeper soil profile. • Grain yield was positively correlated to net SWE, biomass at maturity, and harvest index. • Early plant growth is crucial to develop roots and extract soil water from deeper profile later in the season. [ABSTRACT FROM AUTHOR]