Awned versus awnless wheat spikes: does it matter?

Area of Science:

• Plant genetics and evolution
• Agricultural science
• Crop physiology

Background:

• Wheat (Triticum spp.) exhibits both awned and awnless forms globally.
• Historical evidence indicates awns were predominant for most of wheat's domestication history.
• Selection against awns appears to be a relatively recent phenomenon in wheat cultivation.

Purpose of the Study:

• To investigate the evolutionary history and domestication of wheat awns.
• To quantify the impact of awns on spike photosynthesis and crop yield.
• To analyze the role of awns in different environmental conditions.

Main Methods:

• Analysis of archeological and historical records on wheat morphology.
• Quantification of spike photosynthesis in awned versus awnless wheat.
• Field experiments evaluating yield components under contrasting environments.

Main Results:

• Awns were found to increase grain weight, both directly by enlarging grains and indirectly by affecting distal grain development.
• Increased grain weight due to awns was not linked to enhanced spike photosynthesis.
• A trade-off was observed where awns led to a decrease in the total number of grains per spike.

Conclusions:

• The favorable effects of wheat awns on overall yield are not consistent and depend heavily on environmental factors.
• Awns play a complex role in wheat evolution, influencing grain weight and number with variable yield outcomes.
• Understanding the environmental interactions of awn traits is crucial for wheat breeding and cultivation.