Photosynthetic electron transport rate (ETR) in the littoral herb Launaea sarmentosa known as mole crab in Thailand.

Raymond J Ritchie, Suhailar Sma-Air, Napapit Limsathapornkul, Nedrangsee Pranama, Meakha Nakkeaw, Pramort Kaewnam, Pun Thongchumnum, Kanika Kanjanachatree

Photosynthesis research 2021 Dec

filter terms:

Launaea sarmentosa (Willd.) Sch. Bip ex Kunze (Asteracaeae) is a littoral sand dune herb found in the Indian Ocean region, used as a folk medicine and as a savory vegetable in Thailand. It is in the transition stage from a kitchen & cottage industry to a commercial proposition. Rapid light curves to measure the photosynthetic electron transport rate (ETR) were conducted on the plants over the course of daylight from 6:00 to 18:00 using a PAM fluorometer on plants grown under 50% (nominal) green horticultural and 20% black (nominal) shade cloth and in the open. Plants grown in the open were sun plants. Eopt (µmol photon m-2 s-1) decreased slightly under shade cloth (open air: 890 > green shade cloth, 778 > green shade cloth, 713). Launaea shows limited shade adaptation. ETR decreased under shade cloth on both a surface area and Chl a basis (µmol e- g Chl a-1 s-1) [open air: 388 > (green shade cloth, 209 = black shade cloth, 263)]. Maximum non-photochemical quenching (NPQmax) was significantly decreased under black shade cloth [(open air: 1.02 = green shade cloth, 0.969) > black shade cloth, 0.694]. ETR showed midday inhibition (9:00-15:00) when irradiance exceeded the Eopt of Launaea. Daily total photosynthetic electron transport was (mmol e- m-2 d-1): open air, 1890 ± 157; green shade cloth, 1620 ± 203, black shade cloth, 1217 ± 143. Green shade cloth has no effect on total daily photosynthetic electron transport of Launaea but offers some protection from desiccation and excessive evapotranspiration. Waterlogging decreases ETR by about 40%. Launaea can be grown watered with brackish (½ seawater) water unlike many other vegetables. Launeae is a physiologically undemanding cottage industry/market garden crop suitable for sandy coastline fishing communities. © 2021. The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.

Citation

Raymond J Ritchie, Suhailar Sma-Air, Napapit Limsathapornkul, Nedrangsee Pranama, Meakha Nakkeaw, Pramort Kaewnam, Pun Thongchumnum, Kanika Kanjanachatree. Photosynthetic electron transport rate (ETR) in the littoral herb Launaea sarmentosa known as mole crab in Thailand. Photosynthesis research. 2021 Dec;150(1-3):327-341