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Abstract:
Leaf Economics Spectrum (LES) trait variation underpins multiple agroecological processes and many
prominent crop yield models. While there are numerous independent studies assessing trait variation in crops, to
date there have been no comprehensive assessments of intraspecific trait variation (ITV) in LES traits for wheat
and maize: the world’s most widespread crops. Using trait databases and peer-reviewed literature, we compiled
over 700 records of specific leaf area (SLA), maximum photosynthetic rates (Amax) and leaf nitrogen (N) concentrations,
for wheat and maize. We evaluated intraspecific LES trait variation, and intraspecific trait–environment
relationships. While wheat and maize occupy the upper 90th percentile of LES trait values observed across a
global species pool, ITV ranged widely across the LES in wheat and maize. Fertilization treatments had strong
impacts on leaf N, while plant developmental stage (here standardized as the number of days since planting) had
strong impacts on Amax; days since planting, N fertilization and irrigation all influenced SLA. When controlling for
these factors, intraspecific responses to temperature and precipitation explained 39.4 and 43.7 % of the variation
in Amax and SLA, respectively, but only 5.4 % of the variation in leaf N. Despite a long history of domestication in
these species, ITV in wheat and maize among and within cultivars remains large. Intraspecific trait variation is a
critical consideration to refine regional to global models of agroecosystem structure, function and food security.
Considerable opportunities and benefits exist for consolidating a crop trait database for a wider range of domesticated
plant species.
