New article in Oecologia

Our new article Dew‑induced transpiration suppression impacts the water and isotope balances of Colocasia leaves was just published in a special issue of Oecologia honoring the career of Jim Ehleringer. In collaboration with Paul Gauthier and my PhD advisor Kelly Caylor, this paper looks at the effects of dew deposition on the isotope composition of Colocasia esculenta leaf water. See the abstract below for a quick overview of the study and results or head over to Oecologia’s website to read the full paper.Abstract

Foliar uptake of water from the surface of leaves is common when rainfall is scarce and non-meteoric water such as dew or fog is more abundant. However, many species in more mesic environments have hydrophobic leaves that do not allow the plant to uptake water. Unlike foliar uptake, all species can benefit from dew- or fog-induced transpiration suppression, but despite its ubiquity, transpiration suppression has so far never been quantified. Here, we investigate the effect of dew-induced transpiration suppression on the water balance and the isotope composition of leaves via a series of experiments. Characteristically, hydrophobic leaves of a tropical plant, Colocasia esculenta, are misted with isotopically enriched water to reproduce dew deposition. This species does not uptake water from the surface of its leaves. We measure leaf water isotopes and water potential and find that misted leaves exhibit a higher water potential and a more depleted water isotope composition than dry leaves, suggesting a ∼30% decrease in transpiration rate compared to control leaves. We propose three possible mechanisms governing the interaction of water droplets with leaf energy balance: increase in albedo from the presence of dew droplets, decrease in leaf temperature from the evaporation of dew, and local decrease in vapor pressure deficit. Comparing previous studies on foliar uptake to our results, we conclude that transpiration suppression has an effect of similar amplitude, yet opposite sign to foliar uptake on leaf water isotopes.


New paper out in pre-print

After thinking a lot about pre-print and how they fit in the world of plant research, I have decided to give it a try! My first pre-print entitled “Dew-induced transpiration suppression impacts the water and isotope balances of Colocasia leaves is now available on the bioRxiv: see the article!

The paper examines the effects of dew on transpiration suppression in Colocasia esculenta leaves using stable isotopes of water to track changes in the water status of the leaves. The article has been submitted to a peer-reviewed journal.

Abstract: Foliar uptake of water from the surface of leaves is common when rainfall is scarce and non-meteoric water such as dew or fog is more abundant. However, many species in more mesic environments have hydrophobic leaves that do not allow the plant to uptake water. Unlike foliar uptake, all species can benefit from dew- or fog-induced transpiration suppression, but despite its ubiquity, transpiration suppression has so far never been quantified. Here, we investigate the effect of dew-induced transpiration suppression on the water balance and the isotopic composition of leaves via a series of experiments. Characteristically hydrophobic leaves of a tropical plant, Colocasia esculenta, are misted with isotopically enriched water to reproduce dew deposition. We measure leaf water isotopes and water potential and find that misted leaves exhibit a higher water potential (p < 0.05) and a more depleted water isotopic composition than misted leaves (p < 0.001), suggesting a ∼30% decrease in transpiration rate (p < 0.001) compared to control leaves. We propose three possible mechanisms governing the interaction of water droplets with leaf energy balance. Comparing previous studies on foliar uptake to our results, we conclude that transpiration suppression has an effect of similar amplitude, yet opposite sign to foliar uptake on leaf water isotopes.

https://www.biorxiv.org/content/early/2017/08/30/178293
doi: https://doi.org/10.1101/178293


New paper out in PCE

My new paper is finally available online on Plant, Cell & Environment. For this paper, entitled “Leaf water 18O and 2H maps show directional enrichment discrepancy in Colocasia esculenta“, we looked at spatial patterns of water isotopes in Colocasia esculenta leaves. See the abstract below for a quick overview of the study and results or head to the PCE website to read the full paper.

Abstract

Spatial patterns of leaf water isotopes are challenging to predict because of the intricate link between vein and lamina water. Many models have attempted to predict these patterns, but to date most have focused on monocots with parallel veins. These provide a simple system to study, but do not represent the majority of plant species. Here, a new protocol is developed using a Picarro induction module coupled to a cavity ringdown spectrometer to obtain maps of the leaf water isotopes (18O and 2H). The technique is applied to Colocasia esculenta leaves. The results are compared to isotope ratio mass spectrometry. In C. esculenta, a large enrichment in the radial direction is observed, but not in the longitudinal direction. The string-of-lakes model fails to predict the observed patterns, while the Farquhar-Gan model is more successful, especially when enrichment is accounted for along the radial direction. Our results show that reticulate veined leaves experience a larger enrichment along the axis of the secondary veins than along the midrib. We hypothesize that this is due to the lower major/minor vein ratio that leads to longer pathways between major veins and sites of evaporation.


EEWR Seminar March 27th 2015

I gave the EEWR (Environmental Engineering and Water Resources) departmental seminar on Friday, March 27th 2015. My talk focused on the latest results from the lab experiments I conducted last summer and fall, looking at the impact of dew deposition on Colocasia esculenta‘s energy balance. Please contact me if you would like to hear more on the topic!

See the flyer and abstract here.

 


A summer in the lab

This summer I finally started my own research project. I spent the summer working in the Caylor Lab in Princeton, helped by Craig Sinkler, a student from Rider University who did an internship in our lab this summer. We planted six large bulbs of Colocasia esculenta that we watered until the plants reached maturity. After about 4 weeks of growth, we stopped watering the plants. Every two days, we sprayed the leaves of half of the plants with isotopically spiked water, while the other half of the plants did not get any water. We collected leaves from each treatment and looked at the spatial distribution of water isotopes in the leaf using the Picarro Induction Module. I then built maps of the leaf isotopes for leaves collected at different times within a 4 week long treatment. 

In order to help us interpret the evolution of the spatial patterns of the leaf isotopes, I also started running a water potential experiment in which I leave a leaf dry out under a heat lamp over a period of 10 hours and collect samples every half hour that I run on the WP4C to measure leaf water potential. I have been running the same experiment but spraying the leaf with ultra pure water every hour to look at whether foliar uptake is actually happening in Colocasia esculenta and how it improves water potential. Preliminary results show that foliar uptake is indeed happening!