Petunia (Petunia ×hybrida) cultivars vary in silicon accumulation and distribution

Authors: Boldt, Jennifer; Altland, James

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2020
Publication Date: 1/19/2021
Citation: Boldt, J.K., Altland, J.E. 2021. Petunia (Petunia ×hybrida) cultivars vary in silicon accumulation and distribution. HortScience. 56(3):305-312. https://doi.org/10.21273/HORTSCI15486-20.
DOI: https://doi.org/10.21273/HORTSCI15486-20

Interpretive Summary: Silicon is a beneficial element which helps plants tolerate stress from adverse environmental conditions, nutrient deficiencies or toxicities, insects, and pathogens. Research studies have generally focused on leaf silicon accumulation, overlooking its distribution pattern elsewhere in the plant. Also, research studies often evaluate only one genotype per plant species due to space or resource constraints. Quantifying silicon distribution patterns across multiple genotypes enables us to see how much within-species variation exists. In petunia, roots had higher silicon concentrations than aboveground portions of the plant (i.e., leaves, stems, and flowers). Non-uniform increases in silicon concentration occurred when supplemental silicon was supplied and increased to the greatest extent in roots. Both findings suggest tight regulation of silicon export from roots in this species. The eight petunia cultivars examined did vary in their distribution patterns and in the magnitude of increase in silicon concentration when provided supplemental silicon; for example, root silicon concentration increased 5.9 to 91.6-fold, whereas leaf silicon concentration increased 1.7 to 5.3-fold. This suggests the potential to select genotypes with enhanced Si uptake or preferred Si distribution, which may enhance their stress tolerance.

Technical Abstract: Silicon (Si) is a plant-beneficial element that can alleviate the effects of abiotic and biotic stress. Plants are typically classified as Si accumulators based on foliar Si concentrations (= 1% Si on a dry weight basis for accumulators). Based on this definition, most greenhouse-grown ornamentals are low Si accumulators. However, plants that accumulate low foliar Si concentrations may still accumulate high Si concentrations in other tissues. Additionally, screening cultivars for variability in Si uptake has not been investigated for low Si accumulator species. Therefore, the objective of this study was to assess cultivar variability in Si accumulation and distribution in petunia (Petunia ×hybrida). Eight cultivars (‘Supertunia Black Cherry’, ‘Supertunia Limoncello’, ‘Supertunia Priscilla’, ‘Supertunia Raspberry Blast’, ‘Supertunia Royal Velvet’, ‘Supertunia Sangria Charm’, ‘Supertunia Vista Silverberry’, and ‘Supertunia White Improved’) were grown in a commercial peat-based soilless substrate under typical greenhouse conditions. They were supplemented with either 2 mM potassium silicate (+Si) or potassium sulfate (-Si) at every irrigation. Silicon supplementation increased leaf dry mass but did not affect total dry mass. In plants receiving Si supplementation, leaf Si across cultivars ranged from 1248 to 3541 mg·kg-1, stem Si ranged from 195 to 654 mg·kg-1, flower Si ranged from 253 to 1383 mg·kg-1, and root Si ranged from 4018 to 10,457 mg·kg-1. The distribution of accumulated Si varied between cultivar; in Si-supplemented plants, it ranged from 63.5% to 67.7% in leaves, 10.5% to 22.6% in roots, 9.4% to 17.7% in stems, and 1.6% to 9.6% in flowers.