| Iron-heart Cunninghamia lanceolate is an important new species of Chinese fir,which is hard as iron and extremely resistant to decay.It is the most ideal commercial timber forest germplasm resource in Chinese fir and has high promotion value.Drought is the most common growth adversity of plants.Fertilization is the most effective means to promote seedling growth and improve seedling quality.As a new variety of high-quality Chinese fir,it is of great significance to carry out research on drought resistance and fertilization.In October 2021,Iron-heart Cunninghamia lanceolate obtained the certificate of new plant variety right.At present,Iron-heart Cunninghamia lanceolate is in the preliminary stage of cultivation and promotion.In the drought part of this paper,the annual container seedlings of Iron-heart Cunninghamia lanceolate were used as the experimental materials,and four water gradients were used,with daily full watering as the control.A total of five treatment groups were used to determine nine physiological indicators,and the main component analysis method,subordinate function method and other comprehensive evaluation methods were used to screen the physiological indicators affecting Iron-heart Cunninghamia lanceolate’s drought resistance,in order to find out the key physiological and biochemical indicators related to drought resistance,It also provides a theoretical basis for the efficient breeding and promotion of Iron-heart Cunninghamia lanceolate in the future.In the fertilization part of this paper,the annual seedlings of Iron-heart Cunninghamia lanceolate were used as the experimental materials,and the "3414" experimental design scheme was adopted to set up 14 groups of different fertilization formulas to determine the growth,root system,physiological indicators and element content of each group of seedlings,and the comprehensive evaluation methods such as seedling quality index,principal component analysis and membership function were used to explore the changes of growth and physiological characteristics of Iron-heart Cunninghamia lanceolate seedlings under different fertilization formulas,It is expected to find the most suitable fertilization formula for the growth of Iron-heart Cunninghamia lanceolate seedlings,and provide a theoretical basis for the efficient cultivation and promotion of Iron-heart Cunninghamia lanceolate seedlings in the future.The main research results show that:(1)With the increase of drought stress degree and the extension of time,the relative conductivity of the leaves of Iron-heart Cunninghamia lanceolate seedlings under different drought stress treatments showed an upward trend,but the growth rate gradually slowed down;The activity of peroxidase showed a trend of increasing first and then decreasing;The activity of superoxide dismutase increased first and then decreased;The activity of catalase showed an upward trend;The content of malondialdehyde showed an upward trend;Chlorophyll content showed a declining trend;The soluble sugar content showed an upward trend;The content of soluble protein increased first and then decreased;The content of free proline showed a rising trend.(2)After rehydration under drought stress,the relative conductivity,superoxide dismutase activity and catalase activity of Iron-heart Cunninghamia lanceolate seedlings recovered to a certain extent,but it was still higher than that measured at the first time;Peroxidase activity,soluble sugar content,soluble protein content and free proline content can recover to a slightly higher level than in the early stage of drought;The content of malondialdehyde decreased only slightly;Chlorophyll content only slightly increased.It showed that the stress damage of the seedlings could not be fully recovered in a short time,especially when the damage was large under moderate and severe stress.(3)Iron-heart Cunninghamia lanceolate seedlings could not adapt to severe drought or long-term moderate drought environment,and had certain drought resistance under moderate and mild drought.Mild drought had no significant effect on Iron-heart Cunninghamia lanceolate seedlings.After nearly half a month of severe drought or more than half a month of moderate drought duration,the leaves of Iron-heart Cunninghamia lanceolate seedlings turned yellow or even withered.Therefore,in the process of popularization and breeding,after more than one week of drought duration,attention should be paid to timely supplement water to avoid damage to Iron-heart Cunninghamia lanceolate seedlings.(4)Catalase activity and chlorophyll content are the physiological and biochemical indicators that can directly reflect the drought resistance of the seedlings of Iron-heart Cunninghamia lanceolate.They are highly correlated with the drought resistance,and are the key indicators for breeding excellent drought resistant varieties.The content of malondialdehyde,conductivity,proline content are correlated with the drought resistance.Among the three families in this experiment,the family A had the best drought resistance,followed by the family B,and the family C had the worst drought resistance.(5)The scientific and reasonable fertilization formula can significantly promote the growth of 1-year-old Iron-heart Cunninghamia lanceolate seedlings.Compared with the control group Cl without fertilization,the growth index of most fertilization groups is better than C1.The growth indicators of C9 group with the best growth status are higher than that of the control group C1.C9 group is 94.74%higher than C1 in seedling height,29.67%higher than Cl in ground diameter,58.21%higher than C1 in root surface area,32.35%higher than C1 in average root diameter,19.79%higher than C1 in total root length,197.22%higher than C1 in aboveground biomass,133.33%higher than C1 in underground biomass,and 181.19%higher than C1 in total biomass.(6)Under different fertilization formulas and times,there are differences in the content of N,P,K,Ca,and Mg elements in the leaves,stems,and roots of 1-year-old Iron-heart Cunninghamia lanceolate seedlings.The total content of elements in each part of the control group Cl in June,August and October was ranked in the last and second place,and the total content of elements in the other fertilization groups was significantly higher than that in the control group C1,indicating that formula fertilization can effectively improve the content of elements in each part of the seedlings.In October,the highest total content of elements in leaves,stems and roots of Iron-heart Cunninghamia lanceolate were C11,C11 and C7 groups,respectively,while C11(N3P2K2)and C7(N2P3K2)were the two combinations with the highest fertilization amount in all fertilization groups,indicating that high fertilization amount can significantly increase the total content of elements in various parts of Iron-heart Cunninghamia lanceolate,but high element content does not mean the best growth.Although the total content of elements under the appropriate fertilization amount of C9 group(N2P2K1)is not the highest,the growth index is the best among all fertilization groups.It shows that fertilization is not the more the better,and the appropriate fertilization amount under the reasonable combination of nitrogen,phosphorus and potassium is more suitable for the growth and development of the seedlings.(7)Compared with group C1 without fertilization,fertilization can effectively reduce the content of malondialdehyde in the leaves of annual Iron-heart Cunninghamia lanceolate,and increase the content of chlorophyll,soluble sugar,soluble protein and free proline,thus improving the resistance of Iron-heart Cunninghamia lanceolate seedlings.In October,the content of malondialdehyde in C9 group was 21.40%lower than that in C1 group,and the contents of chlorophyll,soluble sugar,soluble protein and free proline in C9 group were 31.66%,11.56%,4.25%and 85.00%higher than those in C1 group,respectively.(8)In this experiment,the best fertilization formula for Iron-heart Cunninghamia lanceolate seedlings is N2P2K1,that is,1g of nitrogen fertilizer,1g of phosphorus fertilizer and 0.5g of potassium fertilizer per pot.Under the treatment group of this fertilization formula,the seedling height,average root diameter,aboveground biomass,underground biomass and total biomass of Iron-heart Cunninghamia lanceolate seedlings can reach the largest of all groups,and the other indicators are at the upper middle level,and the seedling quality index is also the highest. |
PDF Full Text Request