Root Traits of Twelve Pecan Accessions of Varying Origin

Fine root morphology is strongly affected by genotype, environment, and the interaction between genotype and environment. In surveys of herbaceous plants it has been shown that plants from competitive resource rich habitats generally produce fine roots with greater length per unit root dry mass (specific root length, SRL). Few studies have explored a similar relationship between habitat of origin and root traits within ecotypes of a woody species. We explored differences in a range of seedling fine root traits such as mean and median fine root diameter, diameter distribution, and SRL for twelve Pecan (Carya illinoinensis) accessions of origins that are widely divergent in environmental characteristics but grown under standard conditions in a common location. Preliminary analysis showed that fine roots of these accessions had a mean SRL that range from 37 to 58 m·g^-1. The two most southern accessions (87MX1-2.2 and 87MX5-1.7) exhibited the lowest SRL, while 'Moore', 'Riverside', 'Giles', and 'Elliot' exhibited the highest SRL. With the exception of 'Riverside', which originates from a site with intermediate precipitation (710 mm per year), accessions with the highest SRL originated from sites that receive 1000 mm or precipitation per year. Our data suggest that there is a link between root traits and environment, which we will explore further using principal components analysis where we will include longitude, latitude, precipitation, elevation, mean annual temperature, and soil type at origin.