ABSTRACTS of Papers Presented at the 87th Annual Meeting of the Potato Association of America, Spokane, Washington, August 10-14, 2003

American Journal of Potato Research,  Jan/Feb 2004  

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The effect of planting small whole seed on yield and tuber size distribution of Russet Burbank potatoes. Arsenault, W. J. Agriculture and Agri-Food Canada, Crops and Livestock Research Centre, 440 University Ave., Charlottetown, PEI C1A 4N6.

Traditionally, in North America, potato growers plant their crops using cut seedpieces. However, in Europe, small whole seed is planted. Planting small whole seed eliminates the cost of cutting seed, reduces the transmission of seed-borne pathogens, minimizes seedpiece decay and enhances the performance of some potato planters, especially "cup type" planters. To meet market demand, some potato seed, mostly small whole seed, was imported to PEI in the late 1990s. In 2000, a three year study was initiated to determine the effect of whole seed, rates of N fertility, and in-row seedpiece spacing on the yield and tuber size distribution of Russet Burbank potatoes grown for the processing market. Nitrogen was applied at 168,196 and 224 kg/ha. Each year, whole seed was sized as less or greater then 56 g (depending on the seed available) and a cut seed treatment was included as a check. Total yields varied among years and were low in 2001. Little gain in yield was achieved by increasing the rate of nitrogen more than 168 kg/ha. In-row seedpiece spacings were 28, 33, 38 and 43 cm for seed less then 56 g and 33, 38, 43 and 48 cm for seed greater then 56 g while cut seedpieces were planted 38 cm apart. At a similar spacing (38 cm), results suggest that both sizes of whole seed produced similar yields to cut seed while the larger whole seed produced a larger number of smaller size tubers. Whole seed less then 56 g, spaced at 38 to 43 cm, and seed greater than 56 g, spaced at 43 to 48 cm, produced similar yields of tubers greater than 280 g in size compared to cut seed.

Hypothetical obscured recessive traits in tetraploid Solanum estimated by RAPDs. Bamberg, J. B., and Alfonso del Rio. USDA/ARS, US Potato Genebank, 4312 Hwy 42, Sturgeon Bay, WI 54235.

White tuber flesh, some nematode and virus resistances, glandular hairs, 2n gametes, cold acclimation and starch types are examples that demonstrate that recessive traits can be important in potato. However, recessive phenotypes will not be detected in populations of tetrasomic tetraploid germplasm (e.g., cultivated andigena, wild sucrense) unless the allele frequency is high or very many progeny are screened. We inferred the extent of this problem from RAPD band frequencies. The proportion of banded plants from a sample of 24 was determined with respect to a total of 214 RAPD loci within 7 populations of the wild tetraploid species Solarium sucrense. We then calculated the proportion of recessive phenotypes that would be expected if these bands were recessive alleles, and calculated the sample size needed to detect them. If these random RAPD loci reflected the frequencies of recessive alleles, only 50% of corresponding recessive traits would be detected even with a sample size of 250 tetraploid individuals (P> or =0.95). However, if haploids were generated, 50% of these hypothetical recessive traits would be detected with a sample of only 30 random diploid individuals (P> or =0.95). The US Potato Genebank has over 900 populations of tetraploid tetrasomic species, nearly 1/5 of the collection. Considering that researchers typically evaluate far less than hundreds of plants per population, many valuable undiscovered recessive traits may be practically undetectable at the tetraploid level.

The effect of Potato Virus A (PVA) on yield of Russet Burbank and Russet Norkotah potatoes. Bateman, Melinda, P. Nolte, P. B. Hamm and B. Geary. University of Idaho, Idaho Falls R & E Center, 1776 Science Center Drive, Idaho Falls, ID 83402, Hermiston Agriculture Research & Extension Center, PO Box 105, Oregon State University, Hermiston, OR 97838, University of Idaho, Parma R & E Center, 29603 U of I Lane, Parma, ID 83660.

Potato Virus A (PVA), found in Idaho seed in 1996, had increased to problem levels for certified seed producers in 1999. PVA is a mosaic virus and under the Idaho rules of certification, seed lots with more than 2% mosaic were not eligible for recertification. Information on how this virus effects yield under western US production conditions was nonexistent. For this project, seed lots of Russet Burbank and Russet Norkotah containing significant amounts of PVA were obtained and individual tubers were tested to identify and separate healthy from PVA-infected tubers. Healthy and PVA-infected tubers were cut into seedpieces which were blended together into 50-seed-piece portions to artificially create seed lots with 0%, 4%, 10%, 20%, 50%, and 75% PVA. Plots consisting of four replications of each infection level were planted in Parma, Idaho, and in Hermiston, Oregon. To determine actual virus levels, each plant was tested for virus once at emergence and again at the end of the growing season. Whole plots and single plant harvests were performed to determine the amount of yield loss associated with PVA infection. The single plant harvest data showed a more severe impact on yield than the whole plot data, indicating that healthy plants can probably compensate for infected ones to some extent. Yield loss appears to be less with seed-borne PVA than it is with PVY, but some plants with PVA still suffered up to a 30% decrease in yield. Russet Norkotah seems to be more severely affected by PVA than Russet Burbank.