Identification of dynamic growth of Hedera helix as response to variation in daily light levels

Summary

The dynamic responses in shoot growth of three pot plants ofHedera helix L. ‘Mein Herz‘ in relation to changes in photosynthetic photon flux density (PPFD) is identified. In the experiment a two-level strategy of PPFD to the plants was used. The current level of PPFD on any day was either high or low, and was determined using a pseudo random binary signal (PRBS) both to avoid any correlations between the PPFD and other variables, and to ensure that the dynamic characteristics of the plant growth were present in the data. For each of the three pot plants a discrete dynamic model of growth responses to PPFD was estimated, and an agreement between the parameters of the three models was observed. The results show that not only is the current PPFD level of the current day related to the daily increase in fresh weight, but growth is also a function of the PPFD level of the previous days. With respect to the previous days the effects of PPFD can be described as an exponential decay where from one day to the previous day the effect of PPFD is reduced to 67%, 66% and 80% respectively for the three pot plants in the experiment.