Abstract
The aim of the present research work was to evaluate the similarity and remoteness of the impact of different irrigation regimes for tomatoes (Vitelio variety) and their grouping by main biochemical indicators, using mathematical approaches (cluster analysis and factor analysis). Two-year data from a field experiment was used including a non-irrigation and an optimum option, as well as options for canceled irrigation and low irrigation norms (12 options in total). The experiment was carried out in Plovdiv in the period 2016-2017.
Cluster analysis results were in line with the conclusions from the irrigation and fertilization regime analyses and their impact on the tomato quality indicators. The strongest positive correlation existed between the indicators common dyes and lycopene for both experimental years. There was a strong negative correlation between the indicators lycopene and beta-carotene.
The basic indicators leading to the separation of the irrigation and fertilization options into clusters were the following quality indicators: titratable organic acids, ascorbic acid, common dyes, lycopene and beta-carotene combined in the first factor, responsible for 78.621% of the total dispersion of the variables.
Keywords: tomato, irrigation regime, correlation, cluster analysis, factor analysis