| Plants are often stressed by various environmental factors in the natural environment.Saline-alkali stress is one of the most common environmental stresses,causing serious losses to agricultural production and environmental protection.The edible chrysanthemum is valuable for tea,medicinal and ornamental purposes,and has a broad application prospect.Studying its salt and alkali tolerance is of great significance for making full use of plant resources,improving and using saline soil.In this study,neutral salt NaCl and basic salt Na2CO3 were used to simulate salt stress and alkaline stress,respectively,and a mixed NaCl and Na2CO3 molar ratio of 1:1 was used to simulate mixed salt-alkali stress.Screening and evaluation of salt tolerance of three new varieties of tea chrysanthemums including ’Xia Zhuang’,’Qi Huang Ju’ and ’Xue Yingxia Guang’ and their identification indexes.The effects of salt stress,alkaline stress,and mixed saline-alkali stress on the growth and physiology of different chrysanthemum cultivars during flower bud differentiation and their effects on flowering growth,inflorescence morphology,and yield of different chrysanthemum varieties were studied.And other methods to comprehensively evaluate the salt and alkali tolerance of 3 varieties.The study yielded the following results:1.With the prolongation of salt-alkali stress,proline(Pro),soluble sugar(SS),superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)are all present The trend of increasing first and then decreasing.The test data shows that saline-alkali mixed stress has the greatest damage to chrysanthemum.When the stress concentration was 150 mmol/L in the fifth week of salt-alkali mixed stress,the soluble sugar content of ’Xia Zhuang’,’Qi Huang Ju’ and ’Xue Ying Xia Guang’increased by 30.02%,27.39%and 35.91%respectively.The content of proline increased by 115.78%,120.06%and 124.74%respectively.The difference between the varieties is significant,with the overall increase in ’Summer Makeup’ being the smallest and the increase in ’Xue Yingxiaguang’ being the largest.In the antioxidant enzyme system,the difference in POD was the most significant.When the concentration in the fifth week of stress was 100 mmol/l L,the POD activities of ’Xia Zhuang’,’Qi Huang Ju’ and ’Xue Ying Xia Guang’ increased by 62.41%and 65.66,%,71.75%.Inflorescence malformation rate,malondialdehyde(MDA),relative electrical conductivity(RE)showed a gradual increasing trend;while the relative chlorophyll content(SPAD)value,leaf relative water content(WC),plant height,crown width,corolla diameter,single Plant yield,whole plant fresh weight and whole plant dry weight all showed a gradual decrease trend.The experimental data showed that the salt-alkali mixed stress caused the most damage to the chrysanthemum.When the stress concentration was 150 mmol/L in the fifth week of the salt-alkali mixed stress,the leaf water content of ’Xiazhuang’,’Qihuangju’ and ’Xueyingxiaguang’ Compared with the control,the decrease can reach 48.52%,43.99%,37.61%,the blade SPAD value decreases 60.02%,44.45%,40.52%,the relative conductivity increases-27.99%,26.51%,26.42%,MDA content increases respectively 85.38%,71.57%,67.99%."Xia Zhuang" had the largest increase,and "Xue Ying Xia Guang" had the smallest increase.2.Principal component analysis was used to analyze the average of 9 indicators of various varieties of chrysanthemums under different NaCl,Na2CO3,NaCl and Na2CO3 mixed treatments.The contribution rates are 83.742%,92.852%,and 91.394%,respectively.The comprehensive analysis can extract soluble sugar,proline,CAT activity,and SOD activity.The four physiological indicators with large contribution rates to the first and second main components can be used as salt-tolerant Key indicators for evaluation.3.Comprehensive analysis of various physiological indicators and growth indicators of various varieties of chrysanthemums and fuzzy membership function analysis,the salt tolerance of the three varieties in order from strong to weak:’Xue Yingxiaguang’>’Qi Huangju’>’Summer Makeup’. |
