An anatomical study on abortion process of pistils and stamens in Early Beauty plum.

In order to ascertain the reasons why serious abscission occurred in flower buds of Early Beauty plum cultivar dur- ing bud breaking period in recent years, paraffin microtomy was applied for the observation of abortion of the pistil and sta- men during the later development of flower buds. It was found that early structure differentiation of pistil and stamen of Early Beauty plum could be normally completed; but the succeeding differentiation of sex cell of Early Beauty plum was blocked. Until 24 days before flowering, the outer cells in the anther capsule of stamens began to become abnormal, and ultimately, various types of deformities induced the degradation of flower buds. In contrast, Royal Jewel plum,a normal flowering culti- var, began the development of the mother cell of microspores of the stamen and the ovule swelling of the pistil 20 days before flowering; young pollen grains mostly appeared 10 days before flowering; the integrated ovules of the pistil had developed 7 days before flowering. Considering the occurring time and characteristics of abortion of the pistil and stamen, and warm win- ters encountered in recent years (2005-2006, 2006-2007), the flower abortion of Early Beauty plum might be contributed to the lack of chilling requirement.