Sampling leaves of young potato (Solanum tuberosum) plants for glycoalkaloid analysis

Earlier attempts to measure potato (Solanum tuberosum) leaf glycoalkaloids indicated variability among similar plants, suggesting that a single small sampling of a young plant might not be a reliable measure of composition. I t was also suggested that freeze-dried leaf samples might be less variable than fresh ones. In the present work, variability was minimized by comparin g single leaves from the same stem position of each plant. Comparisons invo lving other leaves indicated that the glycoalkaloid content was not constan t with respect to either time or position on the stem. In addition, the pos sible influence of differences in growing conditions at different times sug gests that repeated plantings should include a known variety as a control t o which other plants are compared. Variability was reduced by calculating g lycoalkaloid concentrations on a dry weight rather than fresh weight basis. The method of drying the samples, however, had no influence on the variabi lity of data. These considerations should be generally applicable to the sa mpling of replicate leaves of any plant for analysis of any components.