Quantifying Solanum chacoense root morphology responses to limited nitrogen supply using in vitro, hydroponic, and field monolith methods

Authors: CHRISTENSEN, CHRISTIAN - University Of Florida; ZOTARELLI, LINCOLN - University Of Florida; HAYNES, KATHLEEN - Retired ARS Employee; COLEE, JAMES - University Of Florida

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2021
Publication Date: 4/29/2021
Citation: Christensen, C., Zotarelli, L., Haynes, K.G., Colee, J. 2021. Quantifying Solanum chacoense root morphology responses to limited nitrogen supply using in vitro, hydroponic, and field monolith methods. American Journal of Potato Research. 98:157–170. https://doi.org/10.1007/s12230-021-09829-0.
DOI: https://doi.org/10.1007/s12230-021-09829-0

Interpretive Summary: Plants with larger root systems are able to forage for nitrogen more efficiently. Commercial potato varieties have a shallow root system and lose a large portion of the nitrogen growers apply, resulting in groundwater contamination. A wild potato species has previously been reported to have a large root system. In order to develop new potato varieties with greater root systems, an accurate, high thru-put method must be developed to screen parental materials for this trait. In this study we compared three different methods for studying root biomass production: tissue culture, hydroponics, and field. We found poor correlation for root system traits among these methods, although a few individuals were identified in the wild species that were better than commercial varieties in two or more of the screening methods. This information will be useful to potato breeders developing potato varieties that require less nitrogen to produce.

Technical Abstract: Solanum chacoense Bitt. (chc) is a short-day adapted wild diploid (2n = 2x = 24) species relative of the commercial potato S. tuberosum L. (tbr) that has demonstrated higher below-ground biomass when cultivated under limited nitrogen (N) supply, suggesting it possesses greater potential for N uptake by increasing root length density (RLD). The objectives of this study were to compare screening methodologies for evaluating RLD responses of chc genotypes and tbr cultivars under limited N supply for the screening of superior rooting chc genotypes. Seventeen genotypes of chc and three commercial tbr varieties were exposed to 0.5 and 1.0 N rates across three screening methodologies: in vitro, hydroponic, and field evaluated at tuber initiation state and plant maturity. An increase in RLD in response to the lower N rate was detected only in vitro. There were no significant correlations of genotype rooting responses between the in vitro and hydroponic or field methods. However, significant correlations of genotype performance for rooting responses between the hydroponic and field methods were observed. Differences amongst the growing conditions and media might have led to different rooting responses amongst genotypes. Although the effect of N rate on rooting parameters was detectable in vitro due to a high level of environmental control, there was a weak genotype correlation of RLD across methodologies in identifying superior rooting genotypes. The chc genotypes 0048-34 and 0053-7 performed in the top 50% for RLD in most instances when tested and significantly outperformed one or more tbr cultivars within each method confirming chc possesses the potential for increasing N foraging responses in future breeding with tbr.