Irrigation and fertilization decrease freezing tolerance of the shrub Senecio filaginoides in the patagonian steppe

CARBONEL SILLETTA L; ARIAS NADIA; CAVALLARO A; SCHOLZ FABIAN; GOLDSTEIN G; BUCCI SANDRA

MADISON

Seminario; 11TH iNTERNATIONAL PLANT COLD HARDINESS SEMININAR; 2018

In Patagonia the asynchrony between water availability and optimum growth temperatures, low nutrient availability and the high intensities of wind, are the main variables that shape plant life forms. The objective of this study was to determine freezing resistance of a evergreen shrub species (Senecio filaginoides) under different water and fertilization treatment in a patagonian steppe. The experiment carried out in 20 plots of 25x25 m with four treatments: control (C), irrigation (I), fertilization (F) and I+F. We determined leaf lethal damage (LT50), ice nucleation temperature (INT), leaf relative water content (RWC) and aboveground growth in 4 plants of S. filaginoides per treatment. We observed that leaf INT exhibited similar values in all the treatments (between -7°C and 8°C), while the largest differences were observed in LT50 values. A 70% of cell membrane damage (LT50) at -25°C and higher leaf RWC was observed in I+F and F treatments. We found a positive linear correlation between leaf RWC and LT50. Aboveground biomass increased under I+F and F treatments. The results suggest that F and I+F treatments decrease frost resistance in this shrub species. Higher amount of freezable water increases cell membrane damage.  Higher water availability to plants has detrimental effects on leaf freezing resistance but these effects could be compensated by increase growth rate during the warm season.