| Dalbegia odorifera is a deciduous tree belonging to the genus Dalbergia in the family Fabaceae.It is also known as Hainan Dalbergia or Hainan Dalbergia squamosa,and is a second-grade national protected plant.D.odorifera originates from Hainan Island in China,and is mainly distributed in the plains or hills of the Jianfengling Mountains,which is about 100 meters above sea level.At present,the research on D.odorifera is mostly focused on introduction and cultivation techniques.The research on the seedling substrate of D.odorifera seedlings is not yet systematic.In this study,the effects of different compound cultivation substrates on the growth and physiological indexes of D.odorifera seedlings were studied based on the determination of the physicochemical characteristics of the composite cultivation substrates composed of different substrate ratios;different combinations of the best cultivation substrate combinations were selected.The amount of fungus fertilizer was used to study the effects of different bacterial fertilizer application rates on the growth and physiological indexes of D.odorifera seedlings;this provided a technical reference and theoretical basis for the cultivation of high quality seedlings of D.odorifera.The results of the study are as follows:1.The ratio of different cultivation substrates has a significant effect on the physical and chemical properties of the soil.The conductivity of the peat soil-containing culture substrate was significantly higher than that of the peat-free soil(loam),and the pH of the peat-containing culture substrate was significantly reduced.Treatment 2 had the highest available phosphorus and alkali-hydrolyzable nitrogen ratios,and the highest available potassium content was for single loam soil(control).2.The ratio of different cultivation substrates had a significant effect on the growth indexes of D.odorifera seedlings.Among them,treatment 2(ie peat:perlite:raft:loam = 12:2:2:4)was significantly greater than the control,root length,total surface area of D.odorifera seedlings in diameter,seedling height,and number of root nodules.The root growth parameters such as the diameter,the average diameter,the total volume,and the total number of apical roots were the largest.3.The ratios of different cultivation substrates had significant effects on biomass,root-shoot ratio and seedling quality index of D.odorifera seedlings.Among them,the biomass,root-shoot ratio,and seedling quality index bacteria of the treatment 2D.odorifera seedlings were significantly greater than other treatments.Explaining that Treatment 2 is a proper cultivation substrate ratio for growing D.odorifera seedlings.4.The ratio of different cultivation substrates had obvious influence on the physiological indexes of D.odorifera seedlings.Among them,the chlorophyll content,soluble sugar content,soluble protein content,root activity,and net photosynthetic rate of treatment 2 were significantly higher than other treatments.Treatment 4(peat:perlite:raft:loam = 6:5:7:2)was lower than the control,but the difference was not significant.5.Different bacterial fertilizer application rates had significant effects on the growth indexes of D.odorifera seedlings.D.odorifera with application of bacterial fertilizer was better than the control without application of bacterial fertilizer.The growth indexes such as ground diameter,seedling height,and height-to-diameter ratio of D.odorifera seedlings showed a trend of increasing first and then decreasing with the increase of bacterial fertilizer application amount.The growth indexes such as ground diameter,seedling height,and height-to-diameter ratio of D.odorifera seedlings treated with B were the highest,and the diameters and heights of seedlings were significantly higher than those of the control,which were 2.66 and 2.53 times that of the control.6.The biomass of D.odorifera seedlings increased first and then decreased with the increase of bacterial fertilizer application.Applying bacterial fertilizer can significantly increase root-shoot ratio and seedling quality index of D.odorifera seedlings,indicating that the application of bacterial fertilizer can promote the root activity and growth of D.odorifera seedlings,and is beneficial to the rational distribution of astaxanthin in D.odorifera seedlings.7.The application of bacterial fertilizer significantly increased the chlorophyll a content and the chlorophyll a/b ratio of D.odorifera seedlings,but decreased the content of chlorophyll b.The application of bacterial fertilizer had significant effects on photosynthetic parameters of D.odorifera seedlings.Among them,the net photosynthetic rate,stomatal conductance and transpiration rate of B treatment were the highest,which were 2.18 times,2.67 times and 2.67 times of the control,respectively.8.The application of bacterial fertilizer had no significant effect on the root activity of D.odorifera,but significantly increased the soluble sugar and soluble protein content of D.odorifera seedlings.The soluble sugar and soluble protein content of D.odorifera seedlings showed a trend of increasing first and then decreasing with the increase of bacterial fertilizer application.The contents of soluble sugar and soluble protein in the B treatment(2 g/plant)were 1.52 and 1.54 times that of the control,respectively.9.The application of bacterial fertilizer significantly increased the activities of protective enzymes(POD,SOD,CAT)of D.odorifera seedlings,of which the treatment of B(2g/plant)had the highest protective enzyme activity.The protective enzyme activity of D.odorifera seedlings showed a trend of increasing first and then decreasing with the increase of bacterial fertilizer application.10.The application of bacterial fertilizer had a significant effect on the enzyme activity in rhizosphere soil of D.odorifera seedlings.With the increase of bacterial fertilizer application,the enzyme activities in the rhizosphere soil of D.odorifera seedlings increased first and then decreased.Among them,soil enzyme activities such as urease,sucrase,phosphatase,and catalase in the rhizosphere of B treatment(2g/plant)were significantly higher than those in the control.In summary,the growth performance and physiological metabolic activity of D.odorifera seedlings treatment 2 in terms of cultivation substrate ratio(peat:perlite:raft:loam = 12:2:2:4)is the best,with the highest seedling quality index..Therefore,the ratio of the cultivating substrate of Treatment 2 is the most suitable for the growth of D.odorifera seedlings.Applying the bacterial fertilizer on the basis of the optimum ratio of the treatment 2 cultivation substrate can significantly promote the activity of enzyme activity in the rhizosphere,promote the growth and physiological metabolic activity of the seedlings,and improve the quality of the seedlings.Among them,the B dose(2g/strain)was the best dose. |
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