Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2013
Publication Date: 1/10/2014
Citation: Shi, Z., Stacks, D., Keller, C., Grant, M., Harsh, J., Letourneau, M., Balogh-Brunstad, Z., Gill, R., Thomashow, L.S., Dohnalkova, A. 2014. Cation uptake and allocation by red pine seedlings under cation-nutrient stress in a column growth experiment. Plant and Soil. 378:83-98. Interpretive Summary: The ability of plants to take up nutrients is affected by environmental stress, but how plants respond to stress for cation nutrients, especially calcium and potassium, is poorly understood. We assessed the impact of varying degrees of nutrient stress on cation nutrient uptake in an experimental plant-mineral nutrient system. Red pine seedlings were grown in sand/mineral mixtures for up to 9 months. Calcium and potassium were supplied as the minerals anorthite and biotite, respectively, mixed with the sand, and as nutrient solutions with varying concentrations of calcium and potassium. The ratios of calcium to strontium and potassium to rubidium were used to estimate the amounts of calcium and potassium dissolved from the mineral nutrient sources in the sand. We found that stress for cation nutrients had little impact on the distribution of carbon within the plant after 9 months of growth, and potassium was the limiting nutrient for production of new plant material. The fraction of potassium in plant material from biotite increased with decreasing potassium supply from nutrient solutions. The mineral anorthite, mixed into the soil, was consistently the major source of calcium regardless of nutrient treatment. We conclude that red pine seedlings exploited more mineral potassium in response to increasing potassium deficiency. This did not occur for calcium since calcium was not limiting to plant growth.
Technical Abstract: Background and aims: Plant nutrient uptake is affected by environmental stress, but how plants respond to cation nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient stress on cation uptake in an experimental plant-mineral system. Methods: Column experiments, with red pine (Pinus resinosa Ait.) seedlings growing in sand/mineral mixtures, were conducted for up to 9 months. The Ca and K were supplied from both minerals and nutrient solutions with varying Ca and K concentrations. Results: Cation nutrient stress had little impact on carbon allocation after 9 months of plant growth and K was the limiting nutrient for biomass production. Measurement of Ca/Sr and K/Rb ratios allowed independent estimation of dissolution incongruency and discrimination against Sr and Rb during cation uptake processes. The fraction of K in biomass from biotite increased with decreasing K supply from nutrient solutions. The mineral anorthite was consistently the major source of Ca, regardless of nutrient treatment. Conclusions: Red pine seedlings exploited more mineral K in response to more severe K deficiency. This did not occur for Ca since Ca was not limiting plant growth. Plant discrimination factors must be carefully considered to accurately identify nutrient sources using cation tracers.