Abstract:In order to overcome the phenomenon of pistil abortion in apricot production and improve the fruit setting rate, we used the flower buds of fruiting branches of ‘Liguangxing’(Prunus armeniaca L. var. glabra Sun S. X.) with different tree vigor (strong tree, moderate tree and weak tree) and different types (bunch shaped fruit branch, short fruit branch, middle fruit branch and long fruit branch) in full fruit period as materials to investigate the flowering phenology and biological characteristics. Paraffin sections were used to observe the morphology of the internal tissue structure of flower buds in the abortion prone period (flower bud differentiation stage, pistil differentiation stage, pollen cell stage and flower bud expansion stage). At the same time, the changes of soluble sugar, starch contents and mineral elements in leaves at different main abortion stages were determined. The results showed that: (1) the average abortion rate of flower bud of weak tree was the highest (91.26%), and that of median tree was the lowest (71.08%). For different types of fruiting branches, the abortion rate of flower bud of flower bundle like fruit branch was the lowest, and that of long fruit branch was the highest. (2) The size of pollen viability was as follows: cluster branches > short branches > medium branches > long branches, and the germination rate was as follows: short branches > cluster branches > medium branches > long branches. The pollen viability of flower type was as follows: pistil is higher than stamen > pistils as long as stamens > pistil is lower than stamen > no pistil, and the germination rate was as follows: pistils as long as stamens > pistil is higher than stamen> pistil is lower than stamen > no pistil. (3) The contents of soluble sugar and starch in leaves at pistil differentiation stage were significantly lower than those at other stages; the contents of P, K and Ca in leaves were higher at early differentiation stage, but decreased significantly at pistil and stamen differentiation stage. (4) Compared with the normal flowers, the abortive flowers mainly showed abnormal ovary development, uneven growth points, atrophy of ovary and stagnation of ovule primordium development. The style of pistil of abortive flower was lower than that of filament, and the number of pollen grains decreased sharply. The results showed that the pistil abortion was serious and the fruit setting rate was very low. The difference of the proportion of abortive flowers was caused by the strength of trees. Whether the pistil development is normal or not is directly related to the normal flowering of ‘Liguangxing’. The development of pistil is blocked and eventually becomes the main form of flower bud degeneration. Leaf carbohydrate and mineral elements and other nutrients participate in and ensure the normal development of flower organs.