Greenhouse set up in 2017
Overview: This greenhouse-based experiment examines
the direct foliar effects of acute, short-term exposure to simulated
acid rain (SAR) on seedlings of three domesticated plant species:
sunflower, radish, and clover. The photo above show the typical
arrangement of plants during the experiment. At least once during
the treatment phase the treatment groups are shifted between
tables and the pots randomized to some extent. Simulated acid
rain of pH 3.5 and pH 2 (tapwater acidified with a 2:1 molar
ratio of sulfuric:nitric acids) is sprayed onto the above-soil
foliage of 10 day old seedlings once daily to completely wet
the foliage and moisten the soil surface for a total of 20 daily
applications. The controls are similarly treated with plain tap
water (typically ~pH 6.8-7.4). The seedlings are also watered
once daily with tapwater either several hours before or after
treatment application.There are 16 replicates (pots of seedlings)
per species per treatment group in 2017. Upon completion of the
treatment phase, the plants are measured for leaf area, dry biomass
per plant, the proportion of plants that exhibit any damage (dead
cells, lesions, spotting, etc.), and the percent leaf area exhibiting
damage. Leaf wettability is examined by placing water drops on
the leaves to observe retention and drop shape (contact angle).
Leaf samples are also prepared and viewed using a scanning electron
microscope to document microscale effects on tissues, surface
structures, and epicuticular wax (view
poster of 2016 experiment SEM images).
Establishment 2017 (1/23/17 - Day 1 SAR application)
Click image to see full size.
Day 12 of SAR Applications
Day 15 SAR applications - Feb 6, 2017.
Appearance at data collection
(Feb 13-14, 2017)
Last SAR applications on Feb 12th, 2017. Total of 20
Droplet formation images
(from 2009 experiment)
ARCHIVAL PHOTOS OF TYPICAL
EFFECTS OF SIMULATED ACID RAIN IN THIS EXPERIMENT
Following are detail shots
of the typical physical effects of the acid treatment on the
pH 2 plants. These photos are from various years, but typify
direct effects we see routinely in this experiment.