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Planta Med 2009; 75 - P-5
DOI: 10.1055/s-2009-1216443

Variations in Temperature Response of Photosynthesis in Drug and Fiber Type Varieties of Cannabis sativa L.

S Chandra 1, H Lata 1, IA Khan 1, 2, MA ElSohly 1, 3
  • 1National Center for Natural Product Research, School of Pharmacy, University of Mississippi, University, MS, 38677, USA
  • 2Department of Pharmacognosy, University of Mississippi, MS, 38677, USA
  • 3Department of Pharmaceutics, School of Pharmacy, University of Mississippi, University, MS 38677, USA

The effect of temperature on photosynthetic characteristics of three high yielding drug type (HP Mexican, MX and W1) and three fiber type (Kimpolty, Zolo 11 and Zolo 15) varieties of Cannabis sativa, originally from different agro-climatic zones worldwide were studied. The results clearly indicate that among three drug type clones, high potency Mexican (HP Mex) clone was found to be the most thermotolerant. Optimum temperature for photosynthesis (Topt) was observed around 30°C in HP Mex whereas, Topt was observed in the range of 25 to 30°C in W1 [1]. A comparatively lower value (25°C) for Topt was observed in MX. Among fiber type clones, Topt was observed around 30°C in Zolo 11 and Zolo 15 (Ukrainian origin) whereas, in Kimpolty (from Switzerland) it was observed around 25°C. Differences observed in water use efficiency (WUE) among the clones at lower temperature were less pronounced at higher temperatures. Higher WUE and, lower stomatal conductance and transpiration in HP Mex indicate that this clone may be suitable for the plantation in relatively dry and exposed sites. Both stomatal and mesophyll components seemed to be responsible for the temperature dependence of photosynthesis (Pn) however, their magnitude varied with the clones. A two to five fold increase in dark respiration with an increase in temperature was observed in clones. However, higher increases were associated with clones having higher rate of photosynthesis, indicating an association between photosynthetic and respiratory rates. The results provide a valuable indication regarding clonal variations in temperature dependence of Pn in Cannabis sativa and may be used as a tool for initial selection of suitable clones for outdoor cultivation or to provide suitable indoor environment depending upon a particular variety/clone. Acknowledgements: The work was supported in part by National Institute of Drug Abuse (NIDA), Contract No. N01DA-0-7707. References: [1] Chandra S, et al. (2008) Physiology and Mol Biol of Plants, 14(4), October 2008 (in press).