Effects of Nitrogen Fertilization on the Leaf Chemical Composition of Two Potato Cultivars under Controlled Conditions

Abstract

Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is the most destructive pest of potato crops and the chemical composition of potato leaves plays an important role in CPB growth and development. Sugars and amino acids can promote CPB development by increasing feeding and flight behaviors, whereas glycoalkaloids are considered as plant defensive compounds to suppress CPB populations. In this study, the effects of nitrogen (N) fertilization on foliar sugar, amino acid, and glycoalkaloid concentrations of two potato cultivars (Russet Burbank and Goldrush) were investigated under controlled conditions. A pot experiment was carried out with five N rates (0, 60, 120, 180, and 240 kg N ha−1) in a randomized complete block design. The 3rd, 4th, and 5th leaves from the top of three randomly selected plants from a plot were collected at 61, 75, 89, and 103 days after planting for the analysis of sugars, glycoalkaloids, and amino acids. Nitrogen fertilization had no significant effect on glycoalkaloid concentrations, however, it quadratically increased foliar sugar and amino acid concentrations. Relatively low sugar and amino acid concentrations were observed at 180 kg N ha−1, suggesting that this N rate may be effective for CPB management. Significant differences in most of the foliar chemicals were observed between two cultivars, warranting further studies to investigate the leaf composition of different potato cultivars under field conditions and their effects on CPB behaviors.