Registration of Three Low Cadmium (HA 448, HA 449, and RHA 450) Confection Sunflower Genetic Stocks

Two maintainer and one restorer confection sunflower (Helianthus annuus L.) genetic stocks were developed and released by the USDA-ARS, Fargo, ND, and the North Dakota Agricultural Experiment Station, Fargo, ND, in 2003; HA 448 (Reg. no. GS-30, PI 639171), HA 449 (Reg. no. GS-31, PI 639172), and RHA 450 (Reg. no. GS-32, PI 639173). These genetic stocks are available for use by confection sunflower industry and public researchers to create germplasms, parental lines, or hybrids with decreased Cd uptake into kernels. Confection sunflower having kernels with a lower Cd content would allow more growers to produce this crop and meet crop Cd limits imposed by kernel purchasers. A guide value (Richtwert) for Cd concentration in confection sunflower was established by Germany in 1992 at 0.60 mg kg dry weight. This value caused considerable concern for the U.S. confection industry with respect to international marketing since seed being produced on poorly drained, fine-textured soils (containing higher chlorides) of North Dakota and Minnesota had kernel Cd concentrations reaching 1.33 mg kg dry weight. Two hundred genotypes, including USDA-ARS germplasm lines, plant introductions from various countries, and interspecific germplasm lines were screened at four locations with two replications at each location in 1994 (Li et al., 1995). The accessions with very low Cd uptake included Primrose (PI 490318) and HA 290 (PI 552935), an accession derived from crosses between cultivars ‘Peredovik’ (PI 345611) and ‘VNIIMK 1646’ (PI 307940) developed in the FSU. Among the USDA-ARS confection germplasm lines, the maintainer HA 323 (NSL 208771) and the restorer RHA 324 (NSL 202282) were intermediate in Cd uptake. Crosses among the accessions and lines were initiated and resulted in the development of lower Cd genetic stocks. HA 448 and HA 449 are F6–derived F7 maintainer genetic stocks selected from the cross HA 323/HA 290. HA 323 (NSL 208771) is a maintainer line released by USDA-ARS and the NorthDakotaAgricultural Experiment Station in 1985 (Miller, 1986a). HA 290 is a maintainer line released by USDA-ARS and the Texas and North Dakota Agricultural Experiment Stations in 1975 (Fick et al., 1979). The pedigree method of breeding was used to develop HA 448 and HA 449. Plants selected in the F2 generation were planted as F3 seed in the USDA-ARS breeding nursery at Fargo, ND, in 1998. The soil series at this location was Fargo (fine, smectitic, frigid Typic Epiaquerts), known to be high in plant-available Cd. F4 seed harvested from the F3 plants were threshed by hand. The samples were hand picked to remove all trash and seed that had been insect damaged. Seeds were dehulled by hand which allowed no Cd contamination of kernel samples from metal machinery. Kernels (5 g per sample) were sent to the USDA-ARS Environmental Chemistry Laboratory, BARC, Beltsville, MD for analysis. The kernels were dry ashed at 4808C overnight; the ash was wetted with 2 mL of concentrated HNO3, and heated to incipient dryness; 10 mL 3 M HCl was added, the beakers heated to reflux for 2 h, and then the solution was filtered and brought to volume in 25-mL volumetric flasks using 0.1 M HCl (final concentration 1 M HCl). Cadmium concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP–OES) using an internal standard. Appropriate ground sunflower kernel analytical reference standards and sample blanks were analyzed with each batch of samples. Remnant F4 seed of the lines with the lowest Cd contents were planted in the USDA-ARS breeding nursery at Fargo, ND, in 1999. Similar selections and Cd analysis were completed on F5 kernels in 2000, and F6 kernels in 2001. F7 lines of two F6 selections were grown in the 2002 breeding nursery and harvested seed bulked to form HA 448 and 449. The Cd content of HA 448 and HA 449 kernels averaged over 3 yr (1999–2001) was 0.75 mg kg (range 0.61–0.84 mg kg) and 0.64 mg kg (range 0.57–0.74 mg kg), respectively. The average Cd content of two check inbred lines, HA 285 (PI 599780) and HA 323, was 1.34 and 0.88 mg kg, respectively. RHA 450 is an F6–derived F7 restorer genetic stock selected from the cross RHA 324/Primrose. RHA 324 (NSL 202282) is a USDA-ARS restorer germplasm line released in 1985 (Miller, 1986b). Primrose (PI 490318) is an ornamental accession with lemon-yellow flowers and was introduced from Poland. The pedigree breeding method was used to develop RHA 450. Plants selected in the F2 generation were planted as F3 seed in the USDA-ARS breeding nursery at Fargo, ND, in 1998. F4 seeds harvested from the F3 plants were hand threshed and kernels analyzed for Cd content as previously described. The Cd content of RHA 450 averaged over 3 yr (1999–2001) was 0.55 mg kg (range 0.44–0.65 mg kg). The average of two check inbred lines, RHA 294 (PI 599764) and RHA 324, was 1.19 and 0.70 mg kg, respectively. Hybrids were produced by emasculating HA 448 and HA 449 and crossing with the restorer line RHA 450. These hybrids were compared with the commercial hybrid, Hybrid 924, in 2000, 2001, and 2002 trials planted at Fargo, ND. The kernel Cd content of hybrids HA 448/RHA 450 and HA 449/RHA 450 averaged 0.68 mg kg (range 0.62 to 0.78 mg kg) and 0.67 mg kg (range 0.65–0.70 mg kg), respectively. The average of Hybrid 924 was 1.38 mg kg (range 1.03–1.57 mg kg). Even though the values exceeded the German Richtwert (0.60 mg kg), planting hybrids utilizing parental inbred lines developed from these genetic stocks on well drained, silty loam, sandy loam, or black calcareous loam soils of the north central states should result in hybrids with kernel Cd contents averaging below the 0.60 mg kg content level. Limited quantities of seed of each genetic stock are available from the Seedstocks Project, Dep. of Plant Sciences, Loftsgard Hall, North Dakota State University, Fargo, ND 58105. We ask that appropriate recognition be made if these germplasms contribute to the development of a new hybrid, breeding line, or germplasm. U.S. Plant Variety Protection will not be requested for HA 448, HA 449, or RHA 450.