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Potato cultivars often show differences in tolerance to metribuzin. As new cultivars are released, it is important for growers to know the cultivar's response to metribuzin to avoid injury and yield loss. Love et. al. established a model which can predict yield loss due to metribuzin injury in Idaho. The model can help scientists and growers quickly evaluate a large number of potato cultivars. The objective of our work is to evaluate this model for application in North Dakota (ND). In 2016, 26 potato genotypes were evaluated for metribuzin sensitivity following the post-emergence application (1.12 a.i./ha) when potato plants are 8-12 inches tall, compared to untreated control plots, per the model protocol, at Inkster, ND. Plant injury was rated as the percent of foliage from an average plant showing typical symptoms 21 days post treatment; plant height was determined prior to harvest. Predicted yield reduction was calculated by comparing treated to untreated plots, using the equation of Love et. al. [1-(1.142+0.176(log(plant height treated/plant height untreated))X 0.00796( foliar injury)]. Most genotypes showed differences for their predicted and actual yield reductions. The model equation predicted yield reductions for AND00272-1R, ND8068-5Russ, ND8305-1 and ND092355CR-2Russ; however, all had a yield increases. Based on one year of evaluation, this model does not appear to accurately predict metribuzin sensitivity in ND., Razi Ibrahim * (G), Harlene H Valenti, and Asunta L Thompson Department of Plant Sciences, North Dakota State University, Fargo, ND Support: USDA Specialty Block Grant Corresponding Author's Email: [...]

Specific gravity (SpGr) is often used to measure the processing quality of potato (Solanum tuberosum L.) tubers for French fries or potato chips because of its strong correlation with dry matter content and ease of measurement. For French fry processing genotypes, the desirable range for mean SpGr is typically 1.080 to 1.095, and a small variance around the mean is essential for product uniformity. Two multi-year, multi-location trials were conducted to investigate the genetics of SpGr in elite russet germplasm. Consistent with earlier studies, the mean SpGr was measured with high repeatability within each environment: the median plot-basis value was 0.83 for a national trial with six locations and 3 yr. In contrast, the median repeatability of the SD between tubers was only 0.21. Thus, multi-environment trials are needed to identify genotypes with a narrow SpGr distribution. Finlay--Wilkinson stability analysis of the mean SpGr established one genotype as an outlier: when best linear unbiased predictions were regressed on the environment means, this genotype had a regression coefficient of 2.1, compared with 0.4 to 1.4 for the others. The genetic correlation between environments showed a consistent regional pattern in mean SpGr over the years. There was a higher mean correlation between environments within the Pacific Northwest (0.97), Upper Midwest (0.91), and Northeast (0.85) than between environments from the different regions (0.35-0.78). Although breeding for national adaptation is an attractive idea, our results suggest that genetic gain may be easier to achieve at the regional level. [ABSTRACT FROM AUTHOR]

Processed potato (Solanum tuberosum L.) products, such as chips and French fries, contribute to the dietary intake of acrylamide, a suspected human carcinogen. One of the most promising approaches for reducing its consumption is to develop and commercialize new potato varieties with low acrylamide-forming potential. To facilitate this effort, a National Fry Processing Trial (NFPT) was conducted from 2011 to 2013 in five states. More than 140 advanced breeding lines were evaluated for tuber agronomic traits and biochemical properties from harvest through 8 mo of storage. Thirty-eight and 29 entries had significantly less acrylamide in French fries than standard varieties Russet Burbank and Ranger Russet, with reductions in excess of 50%, after one and 8 mo of storage, respectively. As in previous studies, the glucose content of raw tubers was predictive of acrylamide in finished French fries (R2 = 0.64-0.77). Despite its role in acrylamide formation, tuber free asparagine was not significant, potentially because it showed relatively little variation in the NFPT population. Even when glucose was included in the model as a covariate, genotype was highly significant (p = 0.001) for predicting acrylamide, indicating there may be yet-unidentified genetic loci to target in breeding. The NFPT has demonstrated that there exist many elite US breeding lines with low acrylamide-forming potential. Our ongoing challenge is to combine this trait with complex quality attributes required by the fry processing industry. [ABSTRACT FROM AUTHOR]