ORDINATION OF 4 BELGIAN SUGAR-BEET CULTIVARS AS A TOOL IN THE DETECTION OF ONTOGENIC PHOTOSYNTHESIS MODULATIONS - PRINCIPAL COMPONENT ANALYSIS USING CYTOLOGICAL, ANATOMICAL AND ECOPHYSIOLOGICAL LEAF CHARACTERISTICS

Principal Component Analysis, an ordination technique frequently used in phytosociological ecology, has been successfully applied in an atte mpt to consolidate unknown factors and processes responsible for influ encing and modulating photosynthesis determining sugar beet leaf chara cteristics. Starting from a rough data matrix which consisted of the o bserved values of 18 cytological, anatomical and ecophysiological leaf parameters, measured in 32 leaf series, this technique calculated the co-ordinates of 32 entities with respect to a whole new set of princi pal axes. The ordination of all leaf entities was highly correlated wi th the relative increase of internal (leaf) area, the total relative s tomatal area and the chlorophyll a content. Since their arrangement on the main principal axis was also strongly determined by plant age, th e conclusion could be drawn immediately that these three leaf paramete rs were significantly modulated by plant age. So, conclusions found in a rather subjective way were confirmed by this mathematical ordinatio n technique.