Research On Comprehensive Evaluation Of Garden Chrysanthemum And Its Cultivation Techniques

Chrysanthemum（Chrysanthemum morifolium Ramat.）is one of the ten traditional famous flowers with a long history of cultivation in China.Garden chrysanthemum has the characteristics of full plant type,many branches,neat and dense flowers,etc.It is one of the important groups of chrysanthemums with huge market demand.In this experiment,a comprehensive evaluation system for garden chrysanthemums was es Tab.lished,and further used for quantification and screening the elite strains that China owns proprietary property rights.According to the needs of large-scale production of novel varieties,the effects of different planting time,pinning times and exogenous hormones on flowering and quality of garden chrysanthemums were further analyzed.The main results are as follows:1.A comprehensive evaluation system for ornamentalness of garden chrysanthemum was es Tab.lished using analytic hierarchy process and K-Means clustering method based on investigating 14 traits including roundness,plant height,number of branches,crown width,population flowering period,number of flowers,time of blooming period,flower coverage,flower color,flower color persistence,flower type,flower diameter,pedicel thickness and hardness in 127 garden chrysanthemums that cultivated by Nanjing Agricultural University,and evaluation and screening were further performed.The results showed that roundness and flower coverage had the greatest impact on the overall ornamental characteristics of the flowering period,followed by flower color.The roundness,flower coverage and flower color accounting for 0.565 of the total weight,while flower type,flower diameter and pedicel thick only accounting for 0.013 of the total weight,respectively.Finally,127 garden chrysanthemums were categorized into excellent,good and poor three groups,among 33 are excellent,accounting for 25.98%;53 are good,accounting for 41.73%;41 are poor,accounting for 32.28%.2.The drought resistance of 81 plant lines was identified using the plug natural drought method,and four related indicators including wilting index,plant height,above-ground fresh weight,and above-ground dry weight were measured,and the drought resistance at seedling stage was divided into 5 grades using the membership function method.There were 1 high drought-resistant strain,16 drought-resistant strains,31 low drought-resistant strains,25drought-unresistant strains,and 8 extremely drought-unresistant strains.The waterlogging resistance of 81 strains was identified by simulating flooding,and four related indicators including wilting index,plant height,above-ground fresh weight,and above-ground dry weight were measured.The waterlogging resistance was divided into 5 grades using the membership function method,including 2 waterlogging-tolerant strains,23 more waterlogging-tolerant strains,31 less waterlogging-tolerant strains,23 waterlogging-tolerant strains,and 2 extremely waterlogging-tolerant strains.The disease resistance of 81 strains was identified by field population observation,and fatality rate and diseased leaf rate were measured.The disease resistance was divided into 3 grades,of which 5 with the best disease resistance,37 moderately resistant,and 39 poorly resistant.Finally,the comprehensive stress resistance evaluation was carried out by the cumulative scoring method,that the P18-11-7,P18-21-8,and P18-32-4 strains had the strongest comprehensive stress resistance.3.Comprehensive analysis of 81 strains selected through the evaluation of ornamentalness in part 1 were performed with 18 indexes including the roundness,plant height,number of branches,crown width,population flowering period,number of flowers,time of blooming period,flower coverage,flower color,flower color persistence,flower type,flower diameter,pedicel thickness and hardness,flowering consistency,drought resistance,waterlogging resistance,and disease resistance.Among roundness and crown width had the greatest effect,with weight values of 0.164,followed by flower color and disease resistance,with weight values of 0.162 and 0.091,respectively.Three grades were obtained according to the comprehensive evaluation of 81 strains using the analytic hierarchy process and K-Means cluster analysis.Among them,28 strains were excellent grade,accounting for 34.57%;35 strains were good grade,accounting for 43.21%;and 18 strains are poor grade,accounting for 22.22%.4.The plant height,crown width,crown height ratio,number of flowers,number of branches,flower diameter,flower neck length,branch length,and ground fresh weight were measured for the early flowering garden C.morifolium’Jinling Muchen’and the autumn garden C.morifolium’Zhongshan Yujuan’grown in pots.The effect on the garden chrysanthemums flowering period and quality of planting dates,May 5^th,May 20^th,June 5^th,and June 20^th and 1-4 topping times were compared.This study found that the postponed date of planting correlated with the delayed flowering time of early flowering garden C.morifolium’Jinling Muchen’,while no obvious effect on autumn garden C.morifolium’Zhongshan Yujuan’.C.morifolium’Jinling Muchen’and C.morifolium’Zhongshan Yujuan’planted on May 5^th,showed the best recorded value of the plant height,crown width,number of flowers and ground fresh weight,high crown-to-height ratio and which represented higher quality for ornament.The increased topping times could significantly delay the flowering process of early-flowering garden chrysanthemum C.morifolium’Jinling Muchen’,but had little effect on autumn C.morifolium’Zhongshan Yujuan’.The increased topping times significantly decreased the plant height and branch length of C.morifolium’Jinling Muchen’and C.morifolium’Zhongshan Yujuan’,but significantly increased the crown width and crown height ratio.The highes crown-to-height ratio and the number of flowers were recorded after the third topping,and the plants were close to hemispherical,shorter branch length and more condensed,which means higher value for ornamental usage.However,some indexes,such as number of flowers and ground fresh weight,decreased after the fourth topping.5.The plant height,crown width,crown height ratio,number of flowers,number of branches,flower diameter,flower neck length,branch length,and fresh weight above ground of early flowering garden C.morifolium’Jinling Muchen’and autumn garden C.morifolium’Zhongshan Yujuan’were investigated to evaluate the effect on garden chrysanthemums quality after gibberellin,cytokinin and ethephon treatments.The results showed that gibberellin had early and prolonged effects on flowering process and population flowering period of garden chrysanthemums.The 80 mg/L treatment had the strongest effect of C.morifolium’Jinling Muchen’,and the 20 mg/L treatment had the strongest effect of autumn garden C.morifolium’Zhongshan Yujuan’on the early flowering and prolonging flowering period.Gibberellin could significantly promote the growth of plant height,flower neck and branch of garden chrysanthemum,but C.morifolium’Zhongshan Yujuan’showed too high plant height and excessively long branches and flower necks,slender branches resulted in lodging.Cytokinin has a strong inhibitory effect on the flowering and population flowering period of the two investigated garden chrysanthemums.The delayed flowering process was positively correlated with the increased concentration.Cytokinin could inhibit the plant height,crown width,number of flowers,flower neck length,branch length,and fresh weight of the garden chrysanthemum,and 100 mg/L and 200 mg/L of cytokinin both showed strong repression.C.morifolium’Zhongshan Yujuan’failed to bud and flower after the treatments of 100 mg/L and 200 mg/L of cytokinin.The high concentration of 200 mg/L ethephon delayed flowering process and shorten the population flowering period of both tested garden chrysanthemums,while no obvious effect was observed in treatments with lower concentrations of ethephon.Ethephon had no significant effect on the quality of early flowering garden C.morifolium’Jinling Muchen’.High concentration of ethephon slightly reduced the number of flowers and fresh weight on the ground of autumn-flower garden C.morifolium’Zhongshan Yujuan’,while no other traits were affect.