IMPACTS OF LOW WATER POTENTIAL ON SOIL SALINITY AND ITS EFFECTS ON CRANBERRY DEVELOPMENT Marie-Élise Samson J. FORTIN, J. CARON, S. PÉPIN NACREW Québec 2013 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. Introduction • 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 Hoffman and al. (1990) Deficit irrigation could cause salinity problems in the root layer and lead to osmotic stress in cranberry plants 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 Material and methods EXPERIMENTS SUMMER 2012 : 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 Material and methods MEASUREMENTS : • 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 Results 2.0 1.8 1.6 EC (dS/m) 1.4 1.2 1.0 375 Kg/ha K2O 0.8 250 Kg/ha K2O 125 Kg/ha K2O 0.6 Control 0.4 0.2 0.0 Date EC (dS/m) obtained weekly with lysimeters Results PHOTOSYNTHESIS MEASUREMENTS 14 Photosynthesis (µmol CO2 m-2s-1) 12 10 8 June 2012 July 2012 6 4 2 0 Dry Dry Dry Dry Moist Moist Moist Moist Control 125Kg/ha 250Kg/ha 375Kg/ha Control 125Kg/ha 250Kg/ha 375Kg/ha Treatments Results ORIGINAL OSMOTIC PRESSURE 2 Original osmotic pressure 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 Ladiges (1975) Dry Dry Dry Dry Moist Moist Moist Moist Control 125Kg/ha 250 Kg/ha 375Kg/ha Control 125 Kg/ha 250Kg/ha 375 Kg/ha Treatment 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 Discussion 0.7 0.7 0.6 0.6 375 Kg/ha K2O 0.2 0.0 10/04/2012 23/07/2012 Date Water extraction (1:1) EC (dS/m) in the greenhouse at the beginning and at the end of the experiment 0.0 0.1 0.1 0.4 0.5 250 Kg/ha K2O 0.3 125Kg/ha K2O 0.3 0.2 Control 0.4 CE EC (dS/m) EC (dS/m) 0.5 Prod A Bieler Prod B Erable Prod C Nadeau Prod D Ncan Prod Water extraction (1:1) EC (dS/m) obtained from four different fields during summers 2010 and 2011 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. 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.