Regulative Effects Of Plant Growth Retardants On The Growth A Nd Development Of Dahlia Pinnata

Taking the high variety of Dahlia pinnata ‘Longshangxiongying’ as test material, usingpotted approach to irrigate plant growth retardants (PP₃₃₃and CCC) of different concentrationwhen the plant height was20cm of dahlia, the morphological indexes，physiological andbiochemical parameters of dahlia leaves under growth retardant treatment were studied in thepaper. Through the analysing of the indexes changes, the paper explored the regulation effectsof PP₃₃₃and CCC on the growth and development of dahlia, and screened appropriate plantgrowth retardant and concentration. The results provided technology basis for the futureextentive production of dwarfing potted cultivar and uncover cultivars under plant growthretardant treatment. It also provided a scientific theoretical basis for the future landscapearchitecture application and promotion.The main results of this paper were as follows:The irrigating treatment of PP₃₃₃（25-125mg/L） and CCC（1000-3000mg/L） significantlyinfluenced vegetative growth indexes and flower indexes of dahlia. Plant height, internodelength and petioel length were decreased, the stem diameter, flower diameter, petal count andpetal area were increased, flowering season was lengthened. Node count and branch countwere not different with the control. Budding stage and anthensis showed uncertain changes.Effects of PP₃₃₃were better than CCC on the dahlia. The plant height of dahlia was dewafedsignificantly under PP₃₃₃treatment and reached potted height （<40cm）. The effects of plantgrowth retardant strengthened as the concentration increased, but the effects of higherconcentration were not better than the other treatment on flower indexes. IP2（50mg/L） andIP3（75mg/L） treatment were the optimal concentration for the morphological indexes ofdahlia.Correlation analysis result showed that flowering season and petal count had an internalrelationgship. The shortening of node length made the plant height be dewafed, flowerdiameter was significantly affected by petal count and petal area. The changes of vegetativegrowth indexes showed obviously facilitation effects on the petal count and petal area underPP₃₃₃and CCC treatment. PP₃₃₃and CCC had remarkable effects on the physiology and biochemistrycharacteristics. The content of chlorophyll, cytoplasmic osmoticum were increased, theactivity of antioxidation enzymes and IAAO improved, the content of MDA decreased. At theearlier stage of treatment, the content of ZT, GA3and IAA were decreased and ABA contentlevel increased. ZT, GA3and IAA content level were elevated, and the content of ABAreduced at the later stage. The content of IBA showed complicated changeable trend, and thereason of this phenomena had not been understood. The effects of plant growth retardant wereweakened as the time lengthened. The IC5treatment of CCC had significantly effects on thephytological indexes of stress resistance. The effects of IP3treatment were better than CCCon the content of endogenesis horomone.Correlation analysis showed that chlorophyll and proline had close relation with theother phological indexe. Cytoplasmic osmoticum and SOD, POD had significantly effects onthe content of MDA. POD had negative correlation with CAT, IAAO and proline had closerelationship. The effects of PP₃₃₃and CCC showed remarkable difference on the correlationbetween IAAO and MDA, POD. Physiological indexes had superior correlation withflowering season and stem diameter under PP₃₃₃treatment. Correlation level was improvedbetween Cytoplasmic osmoticum and antioxidation enzymes, IAAO had significantlycorrelation with proline, the regulative effects of physiological indexes were strenthened onthe plant height and flower appearance character under CCC treatment.The regulative effects of PP₃₃₃and CCC on the vegetative growth depended on influcingthe content of GA₃and IAA. ZT had significantly effects on the flower apperance indexes.Stem diameter and petiole length were regulated by ABA. IBA involved the regulation ofstress resisitance of dahlia, but it had little effects on the morphsiological character. Flowerhad different regulative horomone under different plant growth retardant treatment.Correlation level was improved betweem ZT and vetegative and reproductive growth, ABAhad significantly effects on the plant height and internode length, but the effects of IAA weredecreased on the stem diameter. Under PP₃₃₃and CCC treatment, IAAO had closerelationship with IAA, GA₃, ZT and ABA, the influence of ZT was enhanced on the contentof chlorophyll, soluble sugar and the activity of CAT, ABA had internal relationship withSOD and MDA, but the reason of the negative correlation between ABA and SOD had not been known. ZT had suprior correlation with MDA, ABA and SOD under PP₃₃₃treatment.GA3and IAA had significant correlation with chloropgyll and soluble protein, the regulativeeffects of ZT were enhanced on the activity of SOD.PP₃₃₃had significantly effects on the morphological character and the content ofendogenesis horomone of dahlia. The effects of CCC were better than PP₃₃₃on thephytological indexes of stress resistance. Comprehensive comparison showed the75mg/Lirrigating treatment of PP₃₃₃had the optimal effects on the ornamental value when the plantheight was20cm of dahlia.