Continued Selenium Biofortification of Carrots and Broccoli Grown in Soils Once Amended with Se-enriched S. pinnata.

Gary S Bañuelos,Sadikshya R Dangi,Maria C Zambrano,Irvin S Arroyo

doi:10.3389/fpls.2016.01251

Abstract

Selenium (Se) biofortification has been practiced in Se-deficient regions throughout the world primarily by adding inorganic sources of Se to the soil. Considering the use of adding organic sources of Se could be useful as an alternative Se amendment for the production of Se-biofortified food crops. In this multi-year micro-plot study, we investigate growing carrots and broccoli in soils that had been previously amended with Se-enriched Stanleya pinnata Pursh (Britton) three and 4 years prior to planting one and two, respectively. Results showed that total and extractable Se concentrations in soils (0–30 cm) were 1.65 mg kg-1 and 88 μg L-1, and 0.92 mg kg-1 and 48.6 μg L-1 at the beginning of the growing season for planting one and two, respectively. After each respective growing season, total Se concentrations in the broccoli florets and carrots ranged from 6.99 to 7.83 mg kg-1 and 3.15 to 6.25 mg kg-1 in planting one and two, respectively. In broccoli and carrot plant tissues, SeMet (selenomethionine) was the predominant selenoamino acid identified in Se aqueous extracts. In postharvest soils from planting one, phospholipid fatty acid (PLFA) analyses showed that amending the soil with S. pinnata exerted no effect on the microbial biomass, AMF (arbuscular mycorrhizal fungi), actinomycetes and Gram-positive and bacterial PLFA at both 0–5 and 0–30 cm, respectively, 3 years later. Successfully producing Se-enriched broccoli and carrots 3 and 4 years later after amending soil with Se-enriched S. pinnata clearly demonstrates its potential source as an organic Se enriched fertilizer for Se-deficient regions.

Highlights

Selenium biofortification of food crops has been practiced in Se-deficient regions of different countries by adding inorganic-Se containing fertilizers to soils, e.g., Finland (Alfthan et al, 2010), United Kingdom (UK) (Lyons, 2010), New Zealand (Curtin et al, 2006), and in China (Wu et al, 2015)
Mean total and extractable soil Se concentrations were measured as high as 1.65 mg kg−1 and 88 μg L−1, respectively, at preplant from 0 to 30 cm in planting one and as high as 0.95 mg kg−1 and 48.6 μg L−1 at preplant in planting two
Analysis of soil samples collected at postharvest of planting two from T3 and T4 showed that water soluble and total Se were present at different concentrations from 0 to 120 cm (See Supplementary Tables S3 and S4)

Summary

Introduction

Selenium biofortification of food crops has been practiced in Se-deficient regions of different countries by adding inorganic-Se containing fertilizers to soils, e.g., Finland (Alfthan et al, 2010), United Kingdom (UK) (Lyons, 2010), New Zealand (Curtin et al, 2006), and in China (Wu et al, 2015). Great Britain has undertaken efforts to develop soil amendment practices with inorganic-Se designed to increase dietary Se intake in Selenium Biofortification in Carrots and Broccoli the general population via the Se biofortification of food (Rayman, 2012). For this purpose, the successful use of inorganicSe fertilizers is, strongly dependent on uniform physical soil conditions with consideration of soil types, soil redox potentials, soil pH (Hartfiel and Bahners, 1988), and the absence of high soil sulfate concentrations and elevated organic matter (Terry et al, 2000). Se fertilization strategies must be carefully designed for non-uniform soil growing conditions or in soils with shallow groundwater

Methods

Results

Conclusion