1. IMPACTS OF LOW WATER POTENTIAL ON SOIL SALINITY AND ITS EFFECTS ON CRANBERRY DEVELOPMENT Marie-Élise Samson J. F ORTIN, J. C ARON, S. P ÉPIN NACREW Québec 2013

2. Introduction Agriculture consumes each year 70% of water resources (Burton, 2010) Worldwide, 1/3 of irrigated areas presents salinity issues (Bohn and al., 2001) A good irrigation management is essential in cranberry production to maintain water resources, avoid salinity problems and ensure good economic returns.

3. Introduction Hoffman and al. (1990) In cranberry production, irrigation thresholds were suggested : -4 kPa to -6,5 kPa (Bonin, 2008) Represents a decrease in soil water content Affects the movement of mineral fertilizers applied during plant growth Deficit irrigation could cause salinity problems in the root layer and lead to osmotic stress in cranberry plants

4. Objective Evaluate the effects of different irrigation regimes on the ions profile in a sandy matrix and their impacts on plant development Determine a soil electrical conductivity threshold in cranberry production

5. Material and methods 2 matric potential thresholds -5.5 kPa (moist treatment) -8.5 kPa (dry treatment) A control and three salinity levels obtained with KCl S1 = 125Kg/ha K2O in form of K2SO4 S2 = 125 Kg / ha of K2O in form of KCl S3 = 250 Kg / ha of K2O in form of KCl S4 = 375 Kg / ha of K2O in form of KCl EXPERIMENTS SUMMER 2012 :

6. Material and methods Matric potential (Tensiometers) Water content (TDR, 5TE and EC5) Electrical conductivity (Lysimeters, TDR and 5TE) Ions concentrations (Lysimeters) Photosynthesis (Li-Cor 6 400) Pressure-Volume curves (Pressure chamber) Abortion rates, growth and yield measurements MEASUREMENTS :

7. Results EC (dS/m) obtained weekly with lysimeters

8. Results PHOTOSYNTHESIS MEASUREMENTS

9. Results ORIGINAL OSMOTIC PRESSURE Ladiges (1975)

10. Results YIELD AND GROWTH MEASUREMENTS The different treatments showed no significant effects on… Abortion rate Growth measurements Yield Fruit size Number of seeds in each fruit

11. Discussion Prod AProd BProd CProd D Water extraction (1:1) EC (dS/m) in the greenhouse at the beginning and at the end of the experiment Water extraction (1:1) EC (dS/m) obtained from four different fields during summers 2010 and 2011 EC (dS/m)

12. Conclusion We obtained salinity levels encountered in the fields Conditions were not stressful for plants A salinity inferior to 1 dS/m is not a limiting factor for cranberry production Further experiments (2013-2014) should help us find a salinity threshold in cranberry production. The effects of subsurface irrigation will also be investigated.

13. Thank you! Bohn, H. L., McNeal, B. L., and O'Connor, G. A. 2001. "Soil chemistry." 3e /Ed. Wiley. New York. xi, 307 p. Burton, M. 2010. "Irrigation management : principles and practices." CABI North American Office. Cambridge, MA. x, 375 p. Hoffman, G. J., Howell, T. A., and Solomon, K. H. é. 1990. "Management of farm irrigation systems." American Society of Agricultural Engineers. St-Joseph,MI. 1015 p. Ladiges, P. Y. 1975. Some aspects of tissue water relations in three populations of eucalyptus viminalis labill. New Phytologist. 75: 53-62. Minville, S. 2007. "État de l'écosystème aquatique du bassin versant de la rivière Bécancour : faits saillants 2004-2006, Québec, ministère du Développement durable, de l'Environnement et des Parcs, Direction du suivi de l'état de l'environnement, ISBN 978-2-550-51516-6 (PDF)." 15p.