Dwarf Effect Of Plant Growth Retardants On Musella Lasiocarpa

Using the seeds and seedlings of Musella lasiocarpa as the materials,compared the effect of three retardants: PP333, S3307 and CCC on the morphological characteristics, physiological indexes and endogenous hormone levels by seed soaking, root irrigation and leaf application。The results showed that,(1) Root irrigation with 175 mg·L-1 S3307 every interval of 30d could make the better effect on Musella lasiocarpa.(2) Seed soaking with 10-40 mg·L-1 PP333 and 2-8 mg·L-1 S3307 could decrease the germination, reduce the biomass, dwarf the plant and increase the photosynthetic pigment content, improve the net photosynthetic rate. Seed soaking with 40 mg·L-1 PP333 had the best obvious effect, decreased the pesudostem height and height to 54.38% and 51.82% compared to the CK.(3) Root irrigation and leaf application with 100-400 mg·L-1 PP333 and 50-200 mg·L-1 S3307 could reduce the plant height and pesudostem height , but the effect of root irrigation was better than leaf application.Root irrigation could significantly reduced the plant height, pesudostem height, pesudostem coarseness and leaf area, made the plant type more compact;decreased the activity of POD, SOD; increased the content of photosynthetic pigment, improved the net photosynthetic rate, solar conversion efficiency, water use efficiency and CO2 saturation point but decreased the light and CO2 compensation point.Root irrigation with 200 mg·L-1 S3307 had the best obvious effect, decreased the pesudostem height and height to 70.29% and 67.54% compared to the CK.(4) Seen from the result of the anatomical structure and endogenous hormone level, PP333 and S3307 made no significant effect on cell size, but decrease the cell division so as to reduce the total cell number, eventually to dwarf the plant by the way of decreasing the level of IAA, GA3, ZR and increasing the content of ABA.(5) Seed soaking, root irrigation and leaf application with 7 000-10 000 mg·L-1 CCC could make no significant effect on the plant type of seedlings, contrarily, improved the plant height and biomass; CCC made also no significant effect on the anatomical structure, photosynthetic characteristics, photosynthetic pigment content, anti-oxidative substance and MDA content, and endogenous hormone level. CCC was not suitable for dwarfing Musella lasiocarpa.