Factors And Mechanism Of Embryonic Abortion In Seedless Grapes

Cytological observation was conducted during development of embryos and endosperms in 3 cultivars of stenospermocarpic seedless grapes (Flame Seedless and Dalihongwuhe, Jingkejing) in field and Dalihongwuhe cultured; Concentration of endogenous hormones were detected in ovules of 3 stenospermocarpic seedless grapes (Flame Seedless, Dalihongwuhe, Sultanina) and 1 cultivars of seeded grape (Beichun)during the course of embryo development.The main results were as follows:Characteristics of embryo development in stenospermocarpic seedless grapes Embryo and endosperm developed very well at early stage in stenospermocarpic seedless grapes. Globular embryo, early heart-shaped embryo and cellular endosperm filled with embryo sac were observed at this stage. Subsequently endosperm degenerated, and embryo may aborte too. Only a few embryos went on developing into heart-shaped embryo and later embryo development stages, then embryo aborted and died,which resulted in the seeslessness of grape.Embryologic causes of embryo abortion in stenospermocarpic seedless grapes.The studie results of embryo abortion were as follows:(1)It was found that endosperm degeneration is earlier than embryo abortion by Cytological study. It was proved again that embryo abortion occur after endosperm degeneration by changes of ovules weight. (2)Studies showed that embryos develop very well in cultured ovules, but embryo already aborted in field after 8 weeks. These results showed that embryo abortion might be due to endosperm degeneration, and nutrition deficience of embryo led to embryo abortion.Effect of endogenous hormones on embryo abortion during embryo development Concentrations of endogenous hormones in ovules were determined in different stage of embryo development. It was found that the balance between plant growth promoters and plant growth inhibitors may play a more important role than a single hormone in embryo development. This result suggested that embryo abortion be caused by imbalance between plant growth promoters and plant growth inhibitors.Mechanism of embryo abortion in stenospermocarpic seedless grapesAccording to cytological observations of ovules and determination of endogenous hormones in ovules, it was found that embryo abortion correlated directly to nutrition deficience. Endosperm degeneration induced abnormal changes of endogenous hormones .These may result in embryo abortion ultimately. We concluded that embryo abortion was caused by nutrition deficience and physiological metabolism disorder The best harvest time of different cultivars for embryo rescue.Different cultivars had different harvest time, and the best harvest time was 35~50 days after anthesis approximately. The best inoculated time of Flame Seedless, Dalihongwuhe, Jingkejing was 36d, 49d, 42d after anthesis respectively, that is, the best inoculated time should be about 1 week after decline of ovules weight.