We studied how the content of silica (Si) phytoliths varies during the growing season in the leaves of Phalaris arudinacea and what impact the amount of silicon has on optical properties. The plants were sampled at Lake Cerknica during the growing season of 2012. In the laboratory, we conducted biochemical, morphological and anatomical analysis. We also measured the content phytoliths as well as reflectance and transmission spectra of the leaves.
Optical spectra of the leaves are similar, as are the morphological features. There is an increased amount of UV-absorbing compounds in the leaves of the first sampling and a greater amount of chlorophyll a in the leaves of last sampling. From the dendrogram of similarity it can be observed that young leaves from all samplings are most similar and old leaves of the first sampling most different.
Silicon content did not increase, the minimum Si quantity was measured in the leaves in the second sampling. We did not detect the effect on silicon on optical properties. We noticed that the quantity of silicon and the amount of anthocyanins is anti-correlated. Redundancy analysis has shown that the optical properties are most affected by chlorophyll a, which is which is inversely correlated with the intensity of yellow and green light.