Research

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

photo
Physiological measurements on smooth cord grass in Barataria Bay, LA after the 2010 oil spill. August, 2012.

Some past work

Ratnayaka HH*, Boue S, Dinh T**, Le SB**, Cherubin R**. 2018. Photosynthesis  and kaempferol yields of soy leaves under ABA application and mechanical wounding. Journal of Plant Biochemistry and Physiology 6:215;  doi: 10.4172/2329-9029.1000215

Ratnayaka HH*. 2017. An on-campus botanical tour to promote student satisfaction and learning in a university level biodiversity or general biology course. Education Sciences (1), 18; doi:10.3390/educsci7010018

Ratnayaka HH*, Molin WT, Sterlin g TM. 2012. Comparison of physiological and antioxidant responses of Anoda cristata and cotton to progressive drought. Weed Research 52: 358-366.

Bettmann GT, Ratnayaka HH, Molin WT, Sterling TM. 2006. Physiological and antioxidant responses of cotton and spurred anoda (Anoda cristata) under nitrogen deficiency. Weed Science 54:641-650.

Molin WT, Hugie JA, Ratnayaka HH, Sterling TM. 2006. Spurred anoda (Anoda cristata) competition in wide row and ultra narrow row cotton (Gossypium hirsutum and G. barbadense) management systems. Weed Science 54:651-657.

Ratnayaka HH*, Kincaid D. 2005. Gas exchange and leaf ultrastructure of Tinnevelly senna, Cassia angustifolia, under drought and nitrogen stress. Crop Science 45:840-847.

Ratnayaka HH*, Molin WT, Sterling TM. 2003. Physiological and antioxidant responses of cotton and spurred anoda under interference and mild drought. Journal of Experimental Botany 54:2293-2305.

Ratnayaka HH*, Meurer-Grimes B, Kincaid DT. 2002. Sennoside yields in Tinnevelly Senna affected by deflowering and leaf maturity. HortScience 37:768-772.

Ratnayaka HH*, Meurer-Grimes B, Kincaid DT. 1998. Increasing sennoside yields in Tinnevelly Senna (Cassia angustifolia Vahl): Effects of drought, foliar nitrogen spray and crop type. Planta Medica 64:438-442.

Ratnayaka HH*, Bandara KMC, Weerasinghe ASP. 1993. Cropping systems development with Solanum xanthocarpum in Mahaweli system C of Sri Lanka. Tropical Science 33:163-170.

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

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.asp?AccountID=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

Opusunju N*, Kofi B*, Etuk I*, Cook A*, Combe S, Ratnayaka HH. 2014. Physiological recovery of smooth cord grass (Spartina alterniflora Loisel.) in Barataria Bay after oil spill. State of the Coast Conference, March 18-20, New Orleans, LA. http://www.stateofthecoast.org/image/SOC14_Accepted_Posters_01152014.pdf (page 48, poster#24)

Cook A*, Onuaguluchi D*, Jackson J*, Patterson B*, Gilbert L4, Combe S, Ireland S, Muniruzzaman S, Boue S, Ratnayaka HH. 2013. Elicitation of physiological stress and kaempferol accumulation of soybean by sugar treatment. American Society for Horticultural Science Annual Conference. July 22-25, Palm Desert, CA. http://www.ashs.org/index.php?option=com_content&view=article&id=1302:2013-ashs-undergraduate-student-oral-competition-winners&catid=57:student-membership&Itemid=131

Combe S, Bernik B5, Jackson J*, Ojukwu K*, Davenport I, Knott C, Blum M, Ratnayaka HH. 2012. Comparative physiology of natural and cultivar genotypes of coastal marsh grass, Spartina alterniflora. American Society of Plant Biologists Annual Conference. July 20-24, Austin, TX. http://c.ymcdn.com/sites/my.aspb.org/resource/resmgr/Docs/Final_Program_Book.pdf (page 98, P07010)

3Wiessner G, Dinh T*, Muniruzzaman S, Izumori K, Boue S, Ratnayaka HH. 2011. Photosynthetic and leaf kaempferol profiles of soy seedlings under rare sugar treatment. 5th Rare Sugar Congress – Proceedings p 33. 9-12 Nov. Kagawa, Japan.

Dinh T*, Mustahsan W*, Boue S, Ratnayaka HH. 2011. Photosynthetic biochemistry and kaempferol profiles of soybean under leaf wounding and abscisic acid treatments. American Society for Horticultural Science Annual Conference. 25-28 Sept. Waikaloa, HI. http://www.ashs.org/index.php?option=com_content&view=article&id=988:2011-winnersashs-undergraduate-student-oral-competition&catid=57:student-membership&Itemid=131

Le S*, Cherubin R*, Boue S, Bhatnagar D, McLachlan J, Ratnayaka HH. 2010. Photosynthetic, Antioxidant and anticancer properties of soybean under drought and mechanical wounding. American Society for Horticultural Science Annual Conference. 2-5 August. Palm Desert, CA. http://ashs.confex.com/ashs/2010/webprogram/Paper4201.html

Cherubin R*, Ratnayaka HH. 2009. Photosynthetic Properties of Soybean [Glycine max L. (Merr.)] under drought and mechanical wounding. Annual Biomedical Research Conference for Minority Students, Nov. 4-7. Phoenix, AZ.

Le S*, Ratnayaka HH. 2009. Antioxidant and anticancer properties of soybean under drought and mechanical wounding. Annual Biomedical Research Conference for Minority Students, Nov. 4-7. Phoenix, AZ.

Cherubin R*, Do T*, Rajasekaran K, Gossett D, Ratnayaka HH. 2009. Photosynthetic, antioxidant and leaf ultrastructural responses to drought in two spinach cultivars of contrasting morphology. American Society for Horticultural Science Annual Conference. July 24-28, St. Louis, MO. http://ashs.confex.com/ashs/2009/webprogram/Paper2146.html

Do T*, Carey T*, Rajasekaran K, Ratnayaka HH. 2008. Physiological, growth and leaf surface characteristics toward understanding drought tolerance in Big Chili and Jalapeño pepper. American Society for Horticultural Science Annual Conference. July 21-24. Orlando, FL. HortScience 43:1275-76.

Hardy W*, Carey T*, Burnett A*, Shinkle J, Ratnayaka HH. 2007. Gas exchange and photosystem II responses of two spinach cultivars with contrasting morphology to moderate salt stress. American Society for Horticultural Science Annual Conference. July 16-19. Scotsdale, AZ. HortScience 42:943.

Williams FJ*, Barbarin AM*, Hauber DP, Ratnayaka HH. 2006. Drought acclimation of leaf gas exchange in Jalapeño and Big Chili pepper. American Society for Horticultural Science Annual Conference. July 27-30. New Orleans, LA. HortScience 41:1058.

Shinkle J, Hammer M2, Ratnayaka HH. 2006. Rapid transient induction of increased antioxidants by brief UV-B radiation. American Society of Plant Biologists Annual Conference. Aug. 5-9. Boston, MS.

Barbarin AM*, Williams FJ*, Bettmann GT1, Hauber DP, Ratnayaka HH. 2005. Gas exchange and antioxidant properties of two spinach (Spinacia oleracea L.) cultivars of contrasting morphology. American Society for Horticultural Science Annual Conference. July 18-21. Las Vegas , NV. HortScience 40:1057.

Undergraduate author is underlined.  *Xavier University Undergraduate, 1New Mexico State University Undergraduate, 2Trinity University Undergraduate, 3Warren Wilson College Undergraduate, 4University of Pikeville Undergraduate, 5Tulane University Graduate Student

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