In 1994 and 1995 a pot experiment was carried out to evaluate the tolerance of four citrus rootstocks (sour orange (Citrus aurantium), volkamer lemon (C. volkamericana), Rangpur lime (C. limonia) and Cleopatra mandarin (C. reticulata)) to calcareous soil (22.9% CaCO3). The soil was brought from the North-Western Central area of Egypt (El-Hammam district.). The response of rootstocks seedlings to mycorrhizal infection (Glomus fasiculatum) and/or phosphorous fertilizer application (2 g P2O5/pot) under calcareous soil conditions were also considered. The data indicated the higher tolerance of volkamer lemon to the abovementioned conditions in terms of plant height, stem diameter, top and root dry weights and leaf P content as well as infection percentage and numbers of mycorrhizal fungus spores in seedling roots. Sour orange and Rangpur lime were inferior to volkamer lemon considering the same aspects, while Cleopatra mandarin was the least tolerant. It was also clear that growth of volkamer lemon and Rangpur lime seedlings was more dependent on mycorrhizal fungus than sour orange and Cleopatra mandarin ones. Mycorrhizae-infected seedlings without P fertilization recorded the highest values for all tested growth parameters as well as leaf macro-nutrients content, except leaf Ca level which tended to be reduced. |
