From an Empirical to Conceptual Modeling View of Energy Crop Productivity

Abstract

Abstract.When empirical research provides incomplete data, it is often not accepted, especially if the primary data is slightly controversial. This article investigates this situation exactly, where there is little data and quite unexpected results. A conceptual modeling approach is applied here to supplement the empirical research and to examine the yield obtained from the Silphium perfoliatum energy plant under certain environmental conditions in Lithuania. The designed conceptual model is based on an analysis of informational relationships within the "donor-acceptor" ("source-sink") plant (sub)system. It was found, that the chlorophyll-a amount did not affect the yield, what according to the model, may be determined by the different acceptor activity. Nitrogen and potassium influenced the biomass positively, possibly through the activation of acceptor metabolism and assimilate transport, and the consequent signaling on the photosynthetic apparatus (via cytokinin and sugar). Meanwhile, the high phosphate amount in soil negatively influences the yield. A hypothesis of yield limitation by signaling through the high phosphate levels in the case of slowed down photosynthesis is proposed. In addition to determining the causality of the yield formation, the conceptual modeling enables us to make use of limited empirical data to design future experiments, aimed at testing the hypothesis and verifying the model.

Two Novel Energy Crops: Sida hermaphrodita (L.) Rusby and Silphium perfoliatum L.—State of Knowledge

“…For phosphorus, the highest application of 175 kg P ha −1 (400 kg P 2 O 5 ha −1 as a triple superphosphate) are reported in an experiment by Pichard [73], and the results suggested that S. perfoliatum has very low requirements for P, having no impact on yield after a baseline is reached. By contrast, Šimkūnas et al [114] in Lithuania observed a negative effect on S. perfoliatum yields of an increased soil phosphorus concentration from 220 to 290 mg P 2 O 5 kg −1 . In Germany, Frölich et al [111] recommended the application of magnesium in the year of establishment (50-70 kg ha −1 Mg), with organic fertilization afterwards.…”

“…Šiaudinis et al [33] regard the development of weed control technology for the establishment year as one of the principal causes stopping the widespread cultivation of S. perfoliatum. It is also necessary to study how signal processing affects photosynthesis and growth of S. perfoliatum [114].…”