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Leaf photosynthesis and cold tolerance in Miscanthus genotypes. Kirsten Kørup 1 , Xiurong Jiao 1,5 , Helle Baadsgaard 1 , Thomas Prade 2 , Stanisław Jeżowski 3 , Szymon Ornatowski 3 , Robert Borek 4 , Mathias N. Andersen 1 , Poul Erik Lærke 1 and Uffe Jørgensen 1
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Kirsten Kørup1, Xiurong Jiao1,5, Helle Baadsgaard1, Thomas Prade2, Stanisław Jeżowski3, Szymon Ornatowski3, Robert Borek4, Mathias N. Andersen1, Poul Erik Lærke1 and Uffe Jørgensen1
1 Aarhus University, Department of Agroecology, BlichersAllé 20, DK-8830 Tjele, Denmark; 2 Swedish University of Agricultural Sciences, Department of Agrosystems, SE-230 53 Alnarp, Sweden; 3 Institute of Plant Genetics of the Polish Academy of Sciences, Strzeszyńska 34, 60-479 Poznań, Poland; 4 Institute of Soil Science and Plant Cultivation - State Research Institute, Czartoryskich 8, 24-100 Puławy, Poland; 5Xiurong.Jiao@agrsci.dk
Miscanthusspecies, which are C4 perennial grasses, are considered to be good candidates for a potential high production of biomass. They are of particular interest to meet the bioenergy goals using less land (Somerville et al., 2010). However, the productivity is challenged by inhibition of the photosynthetic capacity at temperatures below 15°C (Purdy et al., 2013).
In unbredMiscanthus, biomass production of up to 20 Mg/ha dry matter has been recorded in Denmark (Jørgensen and Sander, 1997). Identification of genetic differences in cold tolerance may be useful to breed new genotypes with high photosynthetic capacity in a cool temperate climate, which might increase the yield further.
To identify Miscanthusgenotypes with high photosynthetic activity and productivity under cool growth conditions
Materials and methods
Figure 1 Miscanthus in the field (left) and greenhouse (right)
Figure 3 Net photosynthetic rate versus photosyntheticactive radiation (PAR) of sixMiscanthusgenotypes grown under warmconditions (25℃).
Figure 2 Leaf growthmeasurements in the field (left) and gas exchangemeasurements in the climatechamber (right)
Plant material (Fig 1): A total of 15 genotypes ofM. sacchariflorus, M. sinensis, M. tinctorius, M.×giganteusorM.sinensis× M. sacchariflorus.
Leaf growth measurements (Fig. 2, left)
Shoot length was measured every second or third day. Daily growth was calculated for cold and warm periods.
Gas exchange measurements, response of leaf photosynthesis to light measured by CIRAS-2 (PP Systems, Amesbury, MA, US) (Fig. 2, right)
Climate chamber conditions :
Day/night period: 14/10 hour; Temp. (d/n): 24/20ºC (warm), 14/10ºC (cold).
Relative humidity (d/n): 85/85% (warm), 75/85% (cold);
PAR: 670 µmol m-2 s-1;
CO2-conc.: 400 ppm
Leaf temp.:24/14ºC (warm/cold); VPD:1.2/1.0 kPa(warm/cold);
CO2-conc.: 400 ppm
PAR: decreased from 2000 to 0 μmol m-2 s-1 in fourteen steps
Figure 4 Net photosynthetic rate versus photosyntheticactive radiation (PAR) of sixMiscanthusgenotypes grown under coldconditions (14℃).
Figure 5Reduction in Asat from warm to coldconditions. Asatis the net photosynthetic rate at a PAR of 1500 µmolm-2 s-1
Table 1Dailyleafgrowth rates measured in fieldexperimentsduring a cold and a warmperiod in May 2012
Somerville C, Youngs H, Taylor C, Davis SC & Long SP (2010). Feedstocks for LignocellulosicBiofuels. Science. 329:790-792.
PurdySJ, MaddisonAL & Jones LE et al. (2013) Characterization of chilling-shockresponses in four genotypes of Miscanthusreveals the superior tolerance of M.×giganteuscompared with M. sinensis and M. sacchariflorus. Annals of Botany. 111: 999-1013
Jørgensen U & Sander B (1997). Biomass requirement for power production: How to optimise the quality by agricultural management. Biomass and bioenergy. 12: 145-147
Projects and financial support:
BIORESOURCE www.bioresource.dk, The Danish Council for Strategic Research
GrassMarginswww.grass,argin.com.The European Unions’sSeventh Framework Programme (FP7/2007-2013) under grant agreement no. 289461