| The characteristics of calcium absorption, transportation, transference, distribution and nutrition physiology were studied in different tissues and organs (xylem, phloem, flower, fruit, branches and leaves, and pedicel ) of wild Priunus humilis during the development and their correlation analysis. The results showed that the distribution of dry and fresh matter in different tissues and organs changed with growth and development. The accumulation of dry matter in organs highly correlated to their water metabolism and the water metabolism influenced the calcium absorption, transference and allocation directly. The variation of calcium contents mainly appeared in the course of flowering and fruits development. A peak of calcium contents was observed in flowers during the period of flowering, while a valley appeared in xylem and phloem. A peak of calcium contents in all organs was observed during the fruit maturation, except in fruits, it tend to decrease. The calcium mainly distributed in phloem from sprouting shoots to flowering, whereas it mainly distributed in the young plant shoots during the fruit development. The active calcium (soluble calcium) is the main form of absorption and transportation. The main calcium form in the xylem, pedicel, flowers and fruits is calcium pectate, and in phloem and young plant shoots is calcium oxalate.The accumulation of calcium in fruits appeared in two periods, one is the mitotic period of young fruits, which appeared in 45 d after flowering and the accumulation amount accounted for 75% of the single fruit calcium; the other appeared in the period of cell swelling and lasted for about 30 d. The peak of active calcium accumulation appeared in the periods of the two peaks of calcium absorption, calcium pectate is the main form in the mitotic period, while the soluble calcium is the main form in the swelling period. This result showed that the active forms of calcium attributed the most of the absorption of the calcium in the fruit, and it might be the main reason for the high contents of calcium in the fruit. The fertilization is the power for calcium absorption during flowering, and the transpiration of the sprouting shoots leaves is the main power for fruits calcium absorption. The active calcium accumulated mainly in the pedicel, and the accumulation of inactive calcium (calcium oxalate) did not affect the calcium absorption and transference in fruits. The order of calcium contents in different part of wild Prunus humilis fruits was as follows: pulp > pit kernel >pit hull, which accounted for 72.05%, 11.56% and 15.94% of the total calcium contents, respectively. The order of calcium forms accumulated in the fruits was as follows: soluble calcium>calcium pectate>calcium phosphate>calcium oxalate>residual calcium, which accounted for 47.03%, 22.57%, 15.61%, 13.61% and 0.85% of the total calcium contents, respectively. The composition of calcium forms in the wild Prunus humilis fruits is controlled by inheritance, and it differed obviously in different types of heredity. Adding external calcium largely affected the contents and composition of different calcium forms in the fruit, whereas graft had little influence. The calcium forms transformed during the fruit storage, the active calcium components in the fruit from the roots increased and the inactive components decreased, the reverse result was obtained when the fruits were treated with external calcium. The same regularity was observed in the fruit from the graft tree.
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