Potential alternative crop for selenium biofortification under high saline and boron growing conditions: the case of Salsola soda

Authors: Banuelos, Gary; CENTOFANTI, TIZIANNA - Fresno State University; ZAMBRANO, CLEMENCIA - Fresno State University; VANG, KAOMINE - Fresno State University; LONE, TODD - Fresno State University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: The westside of central California is geologically unique because of the existence of natural-occurring selenium (Se) and boron (B) salts in soils and groundwaters of this region. In California, there is a shortage of good quality water available for irrigated agriculture due to severe drought, reductions in water allotments, and growing municipal, urban, and environmental demands. Consequently, other sources of water, including saline ground and drainage waters must be considered for irrigating crops. However, identifying crops that are salt and B tolerant is a prerequisite for any water reuse strategy with poor quality waters implemented in the westside of central California. In this regard, halophytic crops like agretti, which is scientifically known as Salsola soda, may be an alternative salt tolerant plant species to consider for cultivation in saline soil utilizing saline waters. The multi-year field Se biofortification study described herein was established to grow agretti under saline soil and irrigation conditions. In the first two years, agretti was irrigated with low saline water and grown in saline soils. During the last two years of the study, agretti was irrigated with saline water and grown in saline soils. Results showed that saline or low saline irrigation exerted no negative effect on fresh agretti biomass yields. Agretti accumulated moderate levels of selenium with both types of irrigation water This water reuse strategy in saline soils produced selenium enriched agretti, which is a natural process known as selenium biofortification. This is the first field investigation on the feasibility of growing agretti under saline growing conditions as a Se-biofortified crop with saline waters in the westside of the San Joaquin Valley in California.

Technical Abstract: In California, there is a shortage of good quality water available for irrigated agriculture due to severe drought, reductions in water allotments, and growing municipal, urban, and environmental demands. Consequently, other sources of water, including saline groundwater, must be considered for irrigating salt tolerant crops. One such crop is an edible halophyte-agretti ((Salsoda soda)). In this multi-year field study, we evaluated agretti grown as a Se-biofortification crop in typical saline/B-laden soils ( 10 dS/m and 12 mg B/L) and irrigated with saline (3-8 dS/m) and low-saline water (< 1 dS/m) containing B (1-10 mg B/L) and Se (0.02-0.25 mg Se/L) at different application rates (100, 75, and 50 Eto %, respectively). During the four-year study, fresh biomass yields ranged from 1000 to 3000 gm/ m2 and were generally highest at 100 % Eto with either saline or low-saline water. Tissue Se concentrations ranged from 2-3.2 mg Se / kg DW and 0.4-0.5 mg Se/kg DW with saline and low-saline irrigation, respectively. Selenium speciation showed tissue Se present as follows: selenomethionine (SeMet);selenate (SeO 4); methylselenocysteine (MeSeCy2), irrespective of any treatment (i.e., year of planting, saline or low saline irrigation, rate of water application, direct seeding or transplanted. Total phenolics (bioindicator of stress) ranged from 160 to 257 GAE/L and showed no significant differences among all treatments. Regarding toxic ion accumulation, agretti tolerated excessive sodium (Na) and boron (B) and tissue concentrations ranging from 55,000 to 98,000 mg Na/kg DW and 60 and 235 mg B/kg DW, respectively. Results from this multi-year study have identified agretti as a potential alternative Se biofortification crop that tolerates saline irrigation waters when grown in saline, B- and Se-laden soils.