RESEARCH AND COMMERCIALIZATION OF ALYSSUM MURALE AND ALYSSUM CORSICUM AS POTENTIAL NEW NICKEL PHYTOMINING CROPS

Authors: ROSEBERG, RICHARD - OR STATE UNIV, MEDFORD; Chaney, Rufus; LI, YIN-MING - VIRIDIAN LLC, TX; ANGLE, J - DEPT NAT RES, UMD; BREWER, ERIC - VIRIDIAN LLC, TX

Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/2003
Publication Date: 10/12/2003
Citation: Roseberg, R.J., Chaney, R.L., Li, Y., Angle, J.S., Brewer, E.P. 2003. Research and commercialization of alyssum murale and alyssum corsicum as potential new nickel phytomining crops. p. 18. In Proceedings of the Association for the Advancement of Industrial Crops Conference (October 12-15, 2003, Portland, Oregon).

Interpretive Summary:

Technical Abstract: Nickel is used in large quantities for production of stainless steel, rechargeable batteries, etc. The USA currently imports all the Ni it uses. Traditional strip mining is very costly and can be environmentally damaging. However, certain rare plants, called hyperaccumulators, accumulate over 1% Ni dry weight in their above-ground biomass, and thus have the potential to phytoextract Ni from enriched soil, avoiding the cost and problems of traditional mining methods. Alyssum murale and A. corsicum were selected by USDA and Univ. of Maryland researchers as potential temperate zone Ni phytoextraction crops due to their significant biomass production and Ni uptake as observed in the wild. Because little was known about the crop production requirements of these wild species, a series of agronomic and genetic improvement studies were done in SW Oregon in the largest area of Ni-rich serpentine soils in the US. Seed from wild collections made in southern Europe was used in these studies, conducted near Cave Junction, OR, on a classic serpentine soil containing over 4000 mg Ni/kg. The area was prepared using standard farming and plot research equipment appropriate to each experiment. Herbicides used for canola controlled weeds in Alyssum. Crop biomass was harvested by hand and weighed, and plant Ni content was measured using ICP-atomic emission spectroscopy with internal standard. In fertilizer tests, only small amounts of added P were required to obtain full yields. Plant density and biomass yield were improved with added gypsum, but not with lime. Plant density was significantly reduced when the soil was acidified. In planting date tests, the yield from a spring planting date harvested one year later was just as good or better than yields from fall plantings made 1.5 years before harvest, regardless of whether the fall plantings were also harvested on one intermediate harvest date or not. Planting in April, May, or June did not have a significant effect on yield when harvested the following June. Seedbed preparation tests showed that emergence and density tended to be better when seeds were planted on the surface after minimal disturbance compared to those planted at 6 mm depth following more extensive preparation with a rotary tiller. Tests in rocky soil showed that Alyssum germinates readily given minimal soil disturbance. Although early growth is favored by some irrigation, plants that germinate in the spring can persist through the summer and the following winter, although the resulting yield will be less than those that have at least some irrigation through the first summer. Fall seeding will result in a greater number of plants that persist through the following summer if no irrigation is available. Alyssum tends to concentrate the stored Ni in leaves more than stems; leaves senesce and rapidly fall off the plant as it moves into its flowering phase, so harvest is done at early flowering. Plants that germinate in the late fall are less likely to be vernalized than those planted earlier, and thus will persist in the vegetative state longer the following summer, resulting in improved biomass and Ni yield the first year, although flowering behavior and biomass yield will be the same in subsequent summers. Ni uptake was not affected by any of the planting date treatments as long as harvest was made before flowering occurred. A program of classic plant selection and cross pollination, starting with over 160 wild accessions, has resulted in genotypes with a wide variety of growth habits and Ni uptake rates. Subsequent rounds of selection of these genotypes is ongoing. Based on limited agronomic tests, the first commercial fields of Alyssum have been planted in Josephine Co., Oregon. Although early results have been encouraging, many factors are not well understood, making it difficult to consistently and confidently produce predicta