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, 13 (10), e0205452

Grain Number and Grain Yield Distribution Along the Spike Remain Stable Despite Breeding for High Yield in Winter Wheat


Grain Number and Grain Yield Distribution Along the Spike Remain Stable Despite Breeding for High Yield in Winter Wheat

Norman Philipp et al. PLoS One.


Two winter wheat (Triticum aestivum L.) populations, i.e. 180 genetic resources and 210 elite varieties, were compared in a field trial to analyse how grain number and grain yield distribution along the spike changed during the breeding process and how this associates to yield-related traits. Elites showed in average 38% more yield compared to resources. This breeding improvement mainly derived from an increase in grains and yield per spike in addition to grains and yield per spikelet. These increments corresponded to 19, 23, 21 and 25%, respectively. Not much gain in thousand grain weight (4%) was observed in elites as compared to resources. The number of spikelets per spike was not, or even negatively, correlated with most traits, except of grains per spike, which suggests that this trait was not favoured during breeding. The grain number and grain yield distributions along the spike (GDAS and GYDAS) were measured and compared by using a novel mathematical tool. GDAS and GYDAS measure the deviation of a spike of interest from the architecture of a model spike with even grain and yield distribution along all spikelets, respectively. Both traits were positively correlated. Elites showed in average only a 1% improvement in GDAS and GYDAS values compared to resources. This comparison revealed that breeding increased grain number and yield uniformly along the spike without changing relative yield input of individual spikelets, thereby, maintaining the general spike architecture.

Conflict of interest statement

The authors have declared that no competing interests exist.


Fig 1
Fig 1. Origin of the two winter wheat populations.
(A) Origin of 180 genetic resources and (B) origin of 210 elite varieties.
Fig 2
Fig 2. Contrasting values of the grain yield distribution along the spike (GYDAS).
(A) The genetic resource TRI_1218 and (B) the elite variety Limerick as well as (C) an example spike showing spikelet numbering according to the position along the spike.
Fig 3
Fig 3
Distribution of Best Linear Unbiased Estimates (BLUEs) of 12 yield-related traits (A-L), measured in two winter wheat populations of 180 genetic resources (Resource) and 210 elite varieties (Elite). P-value indicates significantly different mean values between populations; ns, not significant.
Fig 4
Fig 4. Distribution of yield-related traits along the spike displayed for the population of 180 genetic resources (Resource) and 210 elite varieties (Elite).
(A) Grain yield per spikelet, (B) grains per spikelet, (C) relative yield contribution per spikelet and (D) average grain weight per spikelet.

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Grant support

AWS was supported by the Federal Ministry of Education and Research of Germany within the GeneBank2.0 Project (Grant FKZ031B0184A). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.