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Copyright of American Journal of Potato Research is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Highlights • Nitrogen fertilizer significantly decreased potato foliar total sugar concentration, which is a stimulant for CPB feeding. • High N rate increased potato foliar concentrations of glycoalkaloids, which are toxic to CPB. • High N fertilizer rates increased marketable tuber yield and N accumulation of potato plants. • Maximum marketable yield, lower sugar and higher glycoalkaloid concentrations were achieved at the N rate of 205 kg N ha−1. Abstract The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is a destructive pest of potato (Solanum tuberosum L.) crops. Leaf sugars are regarded as energy sources for the growth of the CPB, while glycoalkaloids are used to suppress the feeding behaviors of the CPB. The metabolic pathway of these leaf compounds is closely related to nitrogen (N) nutrition. Additionally, N plays an important role in determining tuber yield. The objective of this study was to investigate the effects of N fertilization on the concentrations of sugars and glycoalkaloids in potato leaves and on marketable tuber yield under field conditions in eastern Canada. Experiments were conducted at three sites and five N rates (0, 60, 120, 180, and 240 kg N ha−1) provided in a randomized complete block design. The potato cultivar "Russet Burbank" was used throughout the experiments. Twenty potato plants were randomly selected in each plot and the fourth leaf from the top of each plant was collected at 40, 54, 68, and 82 days after planting (DAP) for analyzing the concentrations of sugars (sucrose, glucose, and fructose) and glycoalkaloids (α-solanine and α-chaconine). Marketable tuber yield was determined along with the whole plant (vine + tuber) N accumulation. A significant decline of the averaged total sugar, including sucrose and glucose, was observed with increasing N rates. The average concentration of total glycoalkaloid, including α-chaconine, increased significantly in response to the increasing N rates. Based on our results, a rate of 205 kg N ha-1 was identified to obtain a maximum marketable tuber yield along with high concentrations of glycoalkaloid and low sugar concentrations which may influence the CPB feeding. [ABSTRACT FROM AUTHOR]