TY - JOUR

T1 - Evolutionary agroecology

T2 - Trends in root architecture during wheat breeding

AU - Zhu, Yong He

AU - Weiner, Jacob

AU - Yu, Ming Xi

AU - Li, Feng Min

PY - 2019

Y1 - 2019

N2 - Root system characteristics determine soil space exploration and resource acquisition, and these characteristics include competitive traits that increase individual fitness but reduce population performance. We hypothesize that crop breeding for increased yield is often a form of “group selection” that reduces such “selfish” traits to increase population yield. To study trends in root architecture resulting from plant breeding and test the hypothesis that increased yields result in part from group selection on root traits, we investigated root growth and branching behavior in a historical sequence of wheat (Triticum aestivum) cultivars that have been widely grown in northwestern China. Plants were grown in gel-filled chambers to examine growth angles, numbers, and lengths of seminal roots, and in soil-filled chambers under eight soil resource levels for fractal analysis of root system architecture. Yield in field was evaluated at standard and low planting densities. Newer cultivars produced higher yields than older ones only at the higher sowing density, showing that increased yield results from changes in competitive behavior. Seminal root number and growth angles were negatively correlated with yield, while primary seminal root length was positively correlated with yield. Roots of higher-yielding modern varieties were simpler and less branched, grew deeper but spread less laterally than modern varieties. The fractal dimension of root branching was negatively correlated with the yield of cultivars at all resource levels. Root:shoot ratio was negatively correlated with yield under high soil resource levels. The results are consistent with the hypothesis that the success of wheat breeding for higher yields over past 100 years in northwestern China has been in part due to unconscious group selection on root traits, resulting in smaller, less branched, and deeper roots, suggesting a direction for further increases in crop yield in the future.

AB - Root system characteristics determine soil space exploration and resource acquisition, and these characteristics include competitive traits that increase individual fitness but reduce population performance. We hypothesize that crop breeding for increased yield is often a form of “group selection” that reduces such “selfish” traits to increase population yield. To study trends in root architecture resulting from plant breeding and test the hypothesis that increased yields result in part from group selection on root traits, we investigated root growth and branching behavior in a historical sequence of wheat (Triticum aestivum) cultivars that have been widely grown in northwestern China. Plants were grown in gel-filled chambers to examine growth angles, numbers, and lengths of seminal roots, and in soil-filled chambers under eight soil resource levels for fractal analysis of root system architecture. Yield in field was evaluated at standard and low planting densities. Newer cultivars produced higher yields than older ones only at the higher sowing density, showing that increased yield results from changes in competitive behavior. Seminal root number and growth angles were negatively correlated with yield, while primary seminal root length was positively correlated with yield. Roots of higher-yielding modern varieties were simpler and less branched, grew deeper but spread less laterally than modern varieties. The fractal dimension of root branching was negatively correlated with the yield of cultivars at all resource levels. Root:shoot ratio was negatively correlated with yield under high soil resource levels. The results are consistent with the hypothesis that the success of wheat breeding for higher yields over past 100 years in northwestern China has been in part due to unconscious group selection on root traits, resulting in smaller, less branched, and deeper roots, suggesting a direction for further increases in crop yield in the future.

KW - crop evolution

KW - evolutionary ecology

KW - group selection

KW - root architecture

KW - seminal root traits

KW - soil resource

KW - wheat cultivars

KW - yield

UR - http://www.scopus.com/inward/record.url?scp=85059071310&partnerID=8YFLogxK

U2 - 10.1111/eva.12749

DO - 10.1111/eva.12749

M3 - Journal article

C2 - 30976306

AN - SCOPUS:85059071310

VL - 12

SP - 733

EP - 743

JO - Evolutionary Applications

JF - Evolutionary Applications

SN - 1752-4563

IS - 4

ER -