Effect of different levels od NaCl-induced salinity on the distribution of P, K, Ca, Mg, Na and Cl in six citrus rootstocks.

Abstract

Asexually propagated plants of the Citrus rootstocks Citrus aurantium (Sour orange), C. volkameriana (Volkamer lemon), C. reticulata (Cleopatra mandarin) Poncirus trifoliata (Trifoliate orange), Swingle citrumelo (Citrus paradisi x Poncirus trifoliata) and Citrus limettioides (Sweet lime) were grown in a 1:1 sand-perlite mixture, under greenhouse conditions and irrigated with 50% Hoagland nutrient solutions containing 0, 20, 40, 60, 80 or 100 mM NaCl. The effect of salinity on P, K, Ca, Mg, Na and Cl concentrations and their partitioning to leaves and shoots (top and basal) and roots of the six rootstocks was studied. The data indicated that the rootstocks Cleopatra mandarin and Swingle citrumelo are the most salt tolerant, while Citrus aurantium, P. trifoliata and C. volkameriana are the most salt sensitive. The results also revealed significant genotypic differences among the six rootstocks concerning the distribution and concentration of the elements P, K, Ca, Mg, Na and Cl. Among the studied rootstocks P. trifoliata, C. volkameriana and Swingle citrumelo had the greatest K concentration in the top leaves, while C. aurantium had the lowest concentration. The most inhibitory effect of NaCl on Mg concentration was recorded in the roots of the rootstocks Sweet lime and Cleopatra mandarin. Among the six rootstocks, Swingle citrumelo and Cleopatra mandarin had the lowest Na concentration, while C. aurantium, Sweet lime and P. trifoliata had the greatest. The greatest Cl concentration was measured in Sweet lime and C. aurantium leaves, while the lowest was recorded in Cleopatra mandarin and Swingle citrumelo leaves.