Plant Ecophysiology
The way different environmental conditions affect plant function, especially photosynthesis is fascinatingly unpredictable. I am especially interested in studying how light-dependent and carbon assimilatory processes adjust in response to environmental stress. I also attempt to find if useful phytochemicals are elicited during such adjustments.
Continuing work
Comparative physiology of wild type (TM) and immature mutant (im) cotton – with Dr. Hee Jin Kim, USDA, New Orleans.
Identification of smooth cord grass genotypes with possible tolerance to petroleum oil

Some past work
Kim HJ*, Kato N, Ndathe R, Thyssen GN, Jones DC, Ratnayaka HH*. 2021. Evidence for thermosensitivity of the cotton (Gossypium hirsutum L.) immature fiber (im) mutant via hypersensitive stomatal activity. PLoS ONE 16(12): e0259562. https://doi.org/10.1371/journal.pone.0259562 *Co-corresponding authors.
Ratnayaka HH. Sangakkara UR. 1988. Cowpea (Vigna unguiculata Walp) as a component of alley cropping. Sri Lankan Journal of Agricultural Science 25:75-82.
* Corresponding author, ** Xavier student
Some student presentations since 2015
Marrero E*, Wilson A, Kim HJ, Ratnayaka HH. 2021. Cotton immature fiber imPPR mutant performs gas exchange differently compared with its isogenic wild type. Plant Biology Worldwide Summit. American Society of Plant Biologists Annual Conference. July 19 – 23. Online. https://www.eventscribe.net/2021/ASPB/fsPopup.asp?Mode=posterinfo&PosterID=404253&query=cotton
Marrero E*, Nguyen A, Kim HJ, Ratnayaka HH. 2020. An analysis of growth characteristics of cotton immature fiber mutant, im, compared with its near isogenic wild type, TM‐1. ERN Conference in STEM. February 6 – 8. Washington, D.C. https://emerging-researchers.org/projects/153-3/
Marrero E*, Vu A, Vu T, Johnson C, Kim HJ, Ratnayaka HH. 2019. Carbon assimilation and fast fluorescence kinetics between cotton thinner fiber mutant, im, and its near isogenic wild type, TM-1, under controlled environment. American Society of Plant Biologists Annual Conference. Aug 3 – 7, San Jose, CA. https://plantbiology.aspb.org/wp-content/uploads/2020/01/Plant-Biology-2019-Posters.pdf – p.557.
Vu A*, Vu T, Stern K, Johnson C, Arasah A*, Kim HJ, Ratnayaka HH. 2018. Gas exchange and light harvesting properties between cotton immature fiber mutant, im, and its near isogenic wild type, TM-1, that differ in fiber wall thickness. American Society of Plant Biologists Annual Conference. July 14 – 18, Montreal, Canada. https://www.eventscribe.com/2018/ASPB/PosterTitles.asp?goToLetter=G&pfp=PosterTitles
Johnson C*, Vu T*, Opusunju N, Arasah A*, Stern K*, Kim HJ, Ratnayaka HH. 2017. Comparative photosynthetic physiology of near isogenic cotton lines differing in the degree of fiber cell wall thickness in cotton (Gossypium hirsutum L.). American Society of Plant Biologists Annual Conference. June 24-28, Honolulu, HI. Poster # 1200-012. https://www.eventscribe.com/2017/ASPB/PosterTitles.asp?h=Posters%20and%20Abstracts
Gordon M*, Arasah A*, Stern K*, Kim HJ, Ratnayaka HH. 2016. Photosynthesis and growth characteristics of cotton immature fiber mutant (im) in comparison with isogenic wild type (TM-1). American Society of Plant Biologists Annual Conference. July 9-13, Austin, TX. http://www.eventscribe.com/2013/ app/tweets.aspAccountID=9908822&EventID=2088&ClientID=253&PresentationID=&BoothID=&PresenterID=&PosterID=63587
Opusunju N*, Humphrey A*, Gabriel K*, Ugbaja C*, Combe S, Boue S, Ratnayaka HH. 2015. Photosynthetic physiology and kaempferol yield affected by leaf treatments in soy plants. American Society for Horticultural Science Annual Conference. August 4-7, New Orleans, LA. https://ashs.confex.com/ashs/2015/poster/papers/index.cgi?username=21392&password=523062
Undergraduate author is underlined.