Root morphology and shoot growth in seedlings of chia ( Salvia hispanica L.)

The use of chia ( Salvia hispanica L.) seeds as functional food is increasing worldwide and research on plant traits is important as the crop spreads. The seedling stage has been identified as crucial for establishment, survival, and competition with weeds but information on chia at this stage is scanty, especially regarding root traits. In this study, 8 genotypes of chia: 4 populations (Australia, Mexico, Peru, Basilicata) and 4 breeding lines (G3, G8, G17, WS) were evaluated under controlled conditions at two early stages (six leaves, S-6; ten leaves, S-10) with the aim to assess growth characteristics and variability in root morphological traits. The shoot height and dry matter were measured together with the following root traits: dry matter and architectural parameters characterized through image analysis of root scans: length, surface, average diameter, tips, forks and crossings. Plants showed a greater phenotypic variation at S-6 than at S-10 (average CV = 40% and 22%, respectively). A high variability was recorded for root biomass, root volume, number of forks and crossings (average CV = 54, 40, 44 and 48%, respectively), while root diameter showed lower variability (average CV = 10%). Four principal components explained more than 97% of the total variance and root length, surface area, volume and average diameter contributed mainly to the variability. Cluster analysis showed that genotypes were very different for morphological root traits. Australia and G8 had the most developed root system with longer and coarser roots. Our results could be used in a breeding program for new cultivars with a more vigorous seedling.