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ASHS 2015 Annual Conference

Photosynthetic Physiology and Kaempferol Yield Affected by Leaf Treatments in Soy Plants

Wednesday, August 5, 2015
Napoleon Expo Hall (Sheraton Hotel New Orleans)
Noble Opusunju, Xavier University of Louisiana, New Orleans, LA
Alanna Humphrey, Xavier University of Louisiana, New Orleans, LA
Kareeba Gabriel, Xavier University of Louisiana, New Orleans, LA
Chiderah Ugbaja, Xavier University of Louisiana, New Orleans, LA
Shannon Combe, Xavier University of Louisiana, New Orleans, LA
Steve Boue, USDA-ARS, New Orleans, New Orleans, LA
Harish Ratnayaka, Xavier University of Louisiana, New Orleans, LA, United States
Environmentally sound plant treatments that can impose mild stress and elicit bioaccumulation of useful phytochemicals are not readily available.  We treated leaves of soy plants at V4 stage by an ABA spray, a dodder spray, leaf piercing and leaf holing to investigate their effects on photosynthesis, photosystem II efficiency and kaempferol accumulation in leaves and roots.  Although photosynthesis was in the order of leaf holing > dodder spray > control > leaf piercing > ABA spray, only ABA vs. any other treatment, and leaf holing vs. leaf piercing were significant.  Stomatal conductance followed the same pattern.  However, instantaneous water use efficiency and air-to-leaf temperature difference were the same across treatments.  Although maximum photosystem II efficiency (Fv/Fm) was the same across treatments, quantum yield (F'v/F'm) was lower in leaf piercing than control or dodder spray.  Nonphotochemical quenching (NPQ) was >100% greater in leaf piercing and ABA spray compared to control.  Concentrations of all four leaf kaempferols tested were greatest in ABA spray.  However root kaempferols were the same across treatments.  Different types of leaf wounding – piercing vs. holing – affect photosynthetic physiology of young soy leaves differently.  ABA spray provides a promising lead as a leaf treatment to elicit leaf kaempferols while leaf holing and dodder spray may boost gas exchange.