| Magnolia wufengensis L.Y.Ma et L.R.Wang is an excellent ornamental varity of trees with various flower pattern and colors.However Magnolia wufengensis are tall trees which is not convenient to be planted in courtyard or indoor pot.The experiment was based on the previous research experience on other tree species and selected using plant growth retardants and cutting strunk as the main technical means to dwarf,investigate the effect of different concentrations of Paclobutrazol,Uniconazole,prohexadione Calcium and different degree of cutting strunk on plant morphology,physiology,plant endogenous hormones.In order to find out the most suitable plant growth retardants kind,concentrations and times of application,as well as the degree of cutting trunks,we can get the effective technical methods for dwarf Magnolia wufengensis.Using three different plant growth retardants(Paclobutrazol,Uniconazole,prohexadione Calcium),three different concentrations(500,1000,1500 mg g-1),three using times(1,3,5 times)in L9(34)orthogonal test on I year old grafted seedlings(Magnolia wufengensis ’JiaoHong2’),the results showed:(1)Spraying Uniconazole 1500 mg·g-1 5 times is the best dwarf treatment,height,diameter and internodal length were significantly smaller,separately were 56.94%、62.62%、72.77%of CK,number of nodes was also significantly reduced compared of CK.(2)Plant growth retardants increased the content of SOD,POD,soluble sugar and soluble protein,decreased the content of MDA.(3)By reducing the content of GA3,IAA and ZT and increasing the content of ABA,the retardants affected the physiology of Magnolia wufengensis,and then change the morphology,resulting in the dwarf.There were 4 treatments for the addition of Uniconazole concentration dwarfing test,which were 0,1500,2000,2500 mg·g-1,the results showed that morphological indexes were not significant when the Uniconazole concentration was high,the leave appeard abnormality like crinkling or adhesion when Uniconazole concentration were 2000 or 2500 mg·g-1.Combined plant growth retardants dwarfing test and addition of Uniconazole concentration dwarfing test,the best combination of dwarf was spraying Uniconazole 1500 mg·g-1 5 times.Cutting strunk dwarf test section has 4 different stem cutting degree:no cutting,cutting 1/4,cutting 1/3,cutting 1/2,results showed that:(1)1/2 cutting processing can achieve the shortest height,minimum diameter,branch number at least,the average height is 120.71cm and the average diameter is 14.62cm,the average number of branches is 5.07 branches,respectively were 54.18%,77.66%,32.49%of CK;(2)SOD activity with the stem cutting degree enhancement firstly increased and then decreased,POD activity,soluble sugar,soluble protein content decreased with the stem cutting strength,cutting 1/2 were 84.56%,50.79%,74.32%of CK,MDA content was on the contrary,strengthen with the increasing degree of cutting strunk,were 157.28%of CK;(3)Cutting strunk removal seedlings crown,hinder the synthesis of endogenous hormones in bud downward transport,GA3,IAA,ZT,ABA were significantly decreased compared with CK,separately were 19.08%,16.25%,39.47%,67.46%of CK,which leads to differences in plant height of Magnolia wufengensis.Plant growth retardants combine cutting strunk test section had 4 sections:CK,only cutting strunk,only spraying plant growth retardants,spraying plant growth retardants combine cutting strunk,results showed that:(1)spraying plant growth retardants combine cutting strunk reduced height to 11.95cm,the diameter was reduced to 5.10cm,the section number decreased to 3.9,internodal length was reduced to 3.28cm,separately were 40.77%,81.40%,59.09%,74.21%of CK;(2)spraying plant growth retardants combine cutting strunk had higher SOD activity,POD activity,soluble sugar,soluble protein content than CK,the MDA content was lower than CK.In addition to the content of soluble protein,the other four physiological indexes closed to the control group CK,and had no significant difference at 0.05 level with CK,the soluble protein was significantly higher than CK.(3)GA3,IAA and ZT content of spraying plant growth retardants combine cutting strunk decreased compared CK,ABA content increased compared with CK.According to the above results,the best measures for the dwarfing of Magnolia wufengensis were sparying Uniconazole 1500 mg·g-1 combine cutting strunk 1/2. |
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