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Relationship Between Dry Matter Contents and Metabolic Enzymes During Potato Tuber Enlargement

To explore the relationship between the dry matter contents of potato tubers and metabolic enzymes, an experiment was designed. Ten individual indicators, including metabolic enzymes, could be reduced to 4 comprehensive indicators by using a principal component analysis. Using these 4 components as independent variables (X) and the dry matter content as the dependent variable (Y), the following linear regression equation was obtained: Y = ‒51.802 ‒ 1.022X5 ‒ 0.034X6 + 0.872X9 + 0.286X10 (R = 0.889, P = 0.012). In a comparison between the dry matter contents (22.74, 16.58 and 20.72%) calculated according to the equation and the measured value (22.96, 17.09 and 19.75%), the absolute error was < 1% and the estimation accuracy was > 95%. These results indicated that the linear regression equation can be used to predict accurately and quickly the dry matter contents during the tuber enlargement stage. Introduction Dry matter is an important indicator of the nutritional content and processing quality of potatoes. Improving the dry matter contents of tubers is an important objective for breeder varietal exploration (Chen and Chen 2015). The synthesis of carbohydrates (dry matter, starch, sugar and protein) is closely related to metabolic enzyme activities in plant during its fruit and seed development (Farrar et al. 2000). Metabolic enzyme levels are determined by the photosynthetic capacity of plants and the fruit sink strength (Ho 1988). To determine sink strength, the metabolic enzymes (important indicators) are determined by the level of sucrose metabolism in sink cells and its storage capacity (Sun et al. 1989, Farrar 1993). Sucrose synthase and starch synthase are key enzymes in the synthesis of carbohydrates in crop grains. In the grain-filling stage, sucrose synthase and starch synthase promote the synthesis of starch and other carbohydrates in grains, increasing grain weight and crop yield (Ian and Johannes 1994, Dong et al. 2003, Gao et al. 2003, Xu et al. 2015). On the other hand, during dry matter accumulation in peanut leaves verily shoots to sucrose phosphate and soluble sugar syntheses in promoting the rapid accumulation of dry matter in growing pods (Cui et al. 2010). The accumulation of potato dry matter begins in the tuber formation stage, with the most rapid accumulation taking place in the tuber enlargement stage (Chen and Chen 2015) as a direct activity of leaf metabolic enzyme. In this study, leaf metabolic enzymes and tuber dry matter contents during the potato tuber enlargement stage were evaluated. In particular, a principal component analysis (PCA) and multivariate linear regression were used to refine metabolic enzyme information and to establish a mathematical model for dry matter content. The model provides a convenient and rapid method for determining the intrinsic relationship between the dry matter contents and metabolic enzymes; it also lays a theoretical foundation for early generation selection and cultivation physiology in potato breeding. *Authors for correspondence: <jlpotato@163.com>. Jilin Academy of Vegetable and Flower Science, Changchun City, Jilin Province, China. Jilin Academy of Agricultural Sciences, Changchun City, Jilin Province, China. DOI: https://doi.org/10.3329/bjb.v50i2.54080