Phenotypic and genetic analysis of spike and kernel characteristics in wheat reveals long-term genetic trends of grain yield components

Abstract

Phenotypic and genetic analysis of six spike and kernel characteristics in wheat revealed geographic patterns as well as long-term trends arising from breeding progress, particularly in regard to spikelet fertility, i.e. the number of kernels per spikelet, a grain yield component that appears to underlie the increase in the number of kernels per spike. Wheat is a staple crop of global relevance that faces continuous demands for improved grain yield. In this study, we evaluated a panel of 407 winter wheat cultivars for six characteristics of spike and kernel development. All traits showed a large genotypic variation and had high heritabilities. We observed geographic patterns for some traits in addition to long-term trends showing a continuous increase in the number of kernels per spike. This breeding progress is likely due to the increase in spikelet fertility, i.e. the number of kernels per spikelet. While the number of kernels per spike and spikelet fertility were significantly positively correlated, both traits showed a significant negative correlation with thousand-kernel weight. Genome-wide association mapping identified only small- and moderate-effect QTL and an effect of the phenology loci Rht-D1 and Ppd-D1 on some of the traits. The allele frequencies of some QTL matched the observed geographic patterns. The quantitative inheritance of all traits with contributions of additional small-effect QTL was substantiated by genomic prediction. Taken together, our results suggest that some of the examined traits were already the basis of grain yield progress in wheat in the past decades. A more targeted exploitation of the available variation, potentially coupled with genomic approaches, may assist wheat breeding in continuing to increase yield levels globally.

Uncovering the Genetic Architecture of Fruiting Efficiency in Bread Wheat: A Viable Alternative to Increase Yield Potential

“…4c). These results are in line with those reported by Würschum et al (2018), who found that increases in GNS were a direct consequence of the continuous increases in GFS, whereas FSS seems not to have changed. Given these results, it could be stated that it is more economical for the wheat crop to generate multiple grains within the same spikelet than multiple spikelets with few grains each.…”

Translating auxin responses into ovules, seeds and yield: Insight from Arabidopsis and the cereals

“…As described in the preceding sections, some insight has already been provided through studies in maize, rice and barley. These confirm that auxin fulfils key functions during reproductive development in a window spanning ovule initiation through to fertilisation, which has a major impact on grain yield (Alqudah et al 2014;Wurschum et al 2018).…”

Are We Getting Better in Using Nitrogen?: Variations in Nitrogen Use Efficiency of Two Cereal Crops Across the United States

“…On average, 20% of winter wheat planting area was categorized as highly erodible cropland and was converted to reserve land by the Conservation Reserve Program, leaving productive lands to support a higher NUE (Vocke & Ali, 2013). A recent study evaluating a panel of 407 winter wheat cultivars for six characteristics of spike and kernel development suggested that some of the key traits were the basis of grain yield gains over the past decades (Würschum et al, 2018). This experiment points out that further exploitations of the available trait variations, integrated with genomic approaches, may assist wheat breeding in continuing to increase yield levels globally.…”

“…From 2000 to 2015, although the national average N fertilizer use rate in winter wheat has decreased bỹ 20 kg N −1 ha −1 yr −1 (Cao et al, 2018), its yield and NUE in most states substantially increased in the same period (Figures 2d and 3b). A recent study evaluating a panel of 407 winter wheat cultivars for six characteristics of spike and kernel development suggested that some of the key traits were the basis of grain yield gains over the past decades (Würschum et al, 2018). On average, 20% of winter wheat planting area was categorized as highly erodible cropland and was converted to reserve land by the Conservation Reserve Program, leaving productive lands to support a higher NUE (Vocke & Ali, 2013).…”