Encelia farinosa is well adapted for drought tolerance as its leaves transform color based on water availability. We were puzzled by a question that any desert botanist must consider. How does the photosynthetic efficiency of E. farinosa fluctuate as it transitions from a state of drought to a state of soil saturation within a 72 hour period? In this experiment we looked at the effects of irrigation on the health and quantum yield of the brittlebush by looking at photosynthetic rates using the portable photosynthesis system LI-COR 6400 when applied to two leaves on a given plant and water potential (ψ) using a Scholander-type pressure chamber on the stems.
We attempted to understand how quickly these processes take place from pre-rainfall conditions to post-rainfall conditions up to 72 hours after. We concluded that E. farinosa does not fluctuate significantly in terms of photosynthetic rate, transpiration, and quantum yield with dry as opposed to irrigated soil. However, transpiration and quantum yield significantly increased for the first 24 hours immediately following rainfall, leading us to speculate whether the plant operates at peak efficiency within this window.
DiCiolli, Gabi; Lawson, Karre; and Reimer, Anders, "A comparison of Brittlebush (Encelia farinosa) productivity and health during drought and post rainfall" (2012). Pepperdine University, All Undergraduate Student Research. Paper 52.