Effect of GA3 and Ethephon On Stamen Development of Rhododendron Delavayi Franch

To extend the bloom duration, plant growth regulator, GA3, ethephon, 2,4-D and daminozide, had been sprayed on the wild populations of R. delavayi. The time of flowering duration was recorded after spraying in our preliminary experiments and the results indicated the extension of bloom time. In order to better understand the effect of GA3 and ethephon with mixture of 2,4-D and daminozide on the florescence, the stamen development was observed using the transmission electron microscope after spraying GA3 and ethephon. The results indicated that 100mg/kg and 200mg/kg GA3 could promote stamen development and the lower concentration was better than that of the higher concentration. The anther development was full and surface structure expanded. A lot of pollen grains were found in the pollen sack. Pollen sack closed and no pollen grain had been seen under 100mg/kg GA3 mixed with the 50mg/kg, 100mg/kg, 200mg/kg daminozide respectively. Anther development was not full and showed surface sunken. This inhibiting effect was enhanced as the increase of daminozide and 2,4-D. Spraying 100mg/kg GA3 mixed the 50mg/kg, 100mg/kg, 200mg/kg 2,4-D respectively, the development of the pollen was decreased with the increase of 2,4-D. At the same time, pollen sack was closed and no pollen grain was observed. Ethephon inhibited the development of stamen with the increase of ethephon concentration. The pollen sack was open and the pollen grain was visible when the wild population R. delavayi were sprayed with 200mg/kg ethephon. The pollen sack was closed under the 400mg/kg ethephon. When 500mg/kg ethephon mixed the 50mg/kg, 100mg/kg, 200mg/kg2,4-D respectively, the pollen development declined as the increase of 2,4-D. When 500mg/kg ethephon mixed the 50mg/kg, 100mg/kg, 200mg/kg daminozide respectively, the pollen development increased with the increase of daminozide. Growth regulators did affact the stamen development and the combinations of grwoth regulators might positively or negatively impacted anther development.