© 2003 Heron Publishing—Victoria, Canada
Tolerance of citrus rootstock seedlings to saline stress based on their ability to regulate ion uptake and transport
Gregorio Fernández-Ballester (1), Francisco García-Sánchez (2), Antonio Cerdá (2) and Vicente Martínez (2, 3)
1. Centro de Biología Molecular y Celular, Universidad Miguel Hernández, Edif. Torregaitán. Avda. del Ferrocarril, s/n, E-03202
Elche, Alicante, Spain / 2. Dpt. of Plant Physiology and Nutrition, Centro de Edafología y Biología Aplicada del Segura (CSIC), Campus Universitario,
E-30100 Espinardo, Murcia, Spain / 3. Author to whom correspondence should be addressed (vicente@cebas.csic.es) / Received March 9, 2001; accepted September 13, 2002; published online February 3, 2003
Summary
Forty-five-day-old seedlings of sour orange (Citrus aurantium L.) and Citrus macrophylla Wester, the most commonly used rootstocks in lemon orchards, were grown in nutrient solutions containing 1 (control), 10,
20, 30 or 60 mM NaCl for 14 days. The effects of salinity on growth, uptake, transport and accumulation of Cl– and Na+ ions in leaves, stem and four root segments were studied. The 60 mM NaCl treatment reduced leaf dry mass more in C. macrophylla (40%) than in sour orange (20%), whereas it reduced root dry mass more in sour orange (36%) than in C. macrophylla (20%). In C. macrophylla, Cl– and Na+ uptake rates were high at the beginning of the saline treatments, but low at the end of the 14-day experiment. In contrast,
sour orange showed high uptake rates at the beginning and end of the experiment. In response to increasing salinity, root
and shoot concentrations of Cl– and Na+ increased in sour orange, but not in C. macrophylla. Different loading characteristics of Cl– and Na+ were observed between young and old segments of the root system. In general, old root segments reached quasi-steady-states
later than young root segments. These results suggest that sour orange and C. macrophylla have different regulatory mechanisms for uptake and transport of Cl– and Na+.
Keywords:
Citrus aurantium, Citrus macrophylla, Na+, K+, Cl– distribution, salinity, salt tolerance.
