Method for improving cassava cutting seedling quality based on dwarfing agent

Abstract

The invention relates to the technical field of cassava cutting seedling breeding, in particular to a method for improving cassava cutting seedling quality based on a dwarfing agent, which comprises the following steps: dwarfing cassava cutting seedlings by using the dwarfing agent, and researching the change rule of endogenous hormones in cassava cutting seedling leaves after the dwarfing agent is added. Therefore, the ZR / GA ratio can be used as an index for evaluating the rooting rate and the germination rate of the cassava in the early stage, and we find that when the ZR / GA is greater than or equal to 1.5 and less than or equal to 2.0, the rooting rate and the germination rate of the cassava cutting seedlings are both greater than 90%. The cassava cutting seedlings are typed based on the rule, then different exogenous hormones are selected as rooting agents according to different types, the influence between varieties is reduced, the cassava cutting seedlings are typed objectively, specific hormones and proportions of the exogenous hormone rooting agents under different types are obtained, the survival rate of the cassava cutting seedlings is greatly increased, and the survival rate of the cassava cutting seedlings is increased. The breeding capability of cassava cutting seedlings is improved.

Description

[Technical field]

[0001] The invention relates to the technical field of breeding cassava cuttings, and in particular to a method for improving the quality of cassava cuttings based on a dwarfing agent. [Background technology]

[0002] Cassava (Manihot esculenta Crantz) is one of the world's three major tuber crops (cassava, potato, sweet potato), native to Brazil, and now widely cultivated in tropical regions around the world. It is one of the main cash crops in Guangxi. The tubers of cassava are rich in starch and are good industrial starch raw materials.

[0003] In the common planting process of cassava, cutting planting is a commonly used asexual breeding method. In cutting breeding, how to improve the quality of cassava seedlings, especially to improve the germination rate and rooting rate of seedlings is the most critical factor in cutting breeding. It has been found in the research of prior art that the thicker the cassava cuttings, the higher the germination rate and rooting rate will be. The prior art often selects thicker cassava stems for cutting propagation. However, in the actual breeding process, the stems of some varieties of seedlings are often thinner. In the prior art, there is a method of using dwarfing agents to dwarf the plants to increase the thickness of the seedlings. Based on this background, the research team also considered using dwarfing agents to treat seedlings to obtain thicker seedlings and improve the quality of cutting seedlings.

[0004] However, in actual work, we found that there are many types of cassava, and different cassava varieties have different appearances, stem thickness, plant height and other indicators. How to evaluate whether the dwarfing agent applied to the seedlings is sufficient and whether the dwarfing time is sufficient often requires waiting until the cassava takes root, sprouts, or even grows into a plant for a comprehensive judgment, so that the plant can be judged well. This leads to a very long test cycle for the entire research during the use of dwarfing agents. In our actual work, we found that after the use of dwarfing agents, the endogenous hormones in cassava leaves changed quickly and were very different from the control. Therefore, if we can study the changing rules of endogenous hormones in cassava leaves after the use of dwarfing agents, and adjust the time and dosage of applying the rooting agent ingredients according to this rule, it will greatly shorten our experimental time. At the same time, it will effectively improve the germination rate and rooting rate of our cuttings, and further improve the quality of cassava cuttings. [Summary of the invention]

[0005] In view of the above, in order to improve the germination rate and rooting rate of cassava cuttings and further improve the quality of cuttings, this application studies the changing law of endogenous hormones under the condition of applying the dwarfing agent paclobutrazol, and types the cassava cuttings according to this law, applies different exogenous hormone rooting agents, and accurately, objectively and effectively improves the quality of cassava cuttings.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for improving the quality of cassava cuttings based on a dwarfing agent, the method comprises the following steps: after treating the cassava cuttings with a dwarfing agent, determining the GA and ZR contents in cassava leaves, and calculating a ZR / GA value; when 1.5≤ZR / GA≤2.0, classifying the cassava cuttings as type I seedlings; when 2.0<ZR / GA, classifying the cassava cuttings as type II seedlings; and when ZR / GA<1.5, classifying the cassava cuttings as type III seedlings; and selecting different exogenous hormones according to the above classifications and spraying them onto the cuttings.

[0008] Furthermore, the dwarfing agent is paclobutrazol.

[0009] Furthermore, the type I seedlings do not need additional application of exogenous hormones, the exogenous hormones applied to the type II seedlings are IAA and / or GA; the exogenous hormones applied to the type III seedlings are GA, IAA and / or NAA.

[0010] Furthermore, the exogenous hormone concentration applied to the type II seedlings is 4 mM GA; or 4 mM IAA; or 44-6 mM GA and 4-6 mM IAA.

[0011] Furthermore, the exogenous hormone concentration applied to the type III seedlings is 2-4 mM GA; or 4 mM IAA; or 2 mM NAA; or 2-6 mM GA, 2-6 mM IAA and 2-3 mM IAA.

[0012] Furthermore, the concentration of paclobutrazol is 20 mg / L.

[0013] Furthermore, the paclobutrazol is applied by soaking the cassava cuttings for 2-4 hours.

[0014] Furthermore, the exogenous hormone is sprayed on the 5th and 10th day after cutting planting.

[0015] The present invention also includes a method for evaluating the germination rate and / or rooting rate of cassava cuttings based on a dwarfing agent. The method comprises the following steps: treating the cassava cuttings with the dwarfing agent, determining the GA and ZR contents in the cassava leaves, and calculating the ZR / GA value; when 1.5≤ZR / GA≤2.0, the rooting rate and germination rate of the cassava cuttings are both greater than 90%.

[0016] The present invention has the following beneficial effects:

[0017] 1. The present invention uses a dwarfing agent to dwarf cassava cuttings, which effectively improves the thickness of the cassava cuttings. At the same time, by studying the change law of endogenous hormones in the leaves of cassava cuttings after adding the dwarfing agent, it is found that the ZR / GA ratio can be used as an indicator for judging the rooting rate and germination rate of cassava in the early stage. We found that when 1.5≤ZR / GA≤2.0, the rooting rate and germination rate of the cassava cuttings are both greater than 90%.

[0018] 2. According to the rules of cassava endogenous hormones, dwarfing agents, rooting rate and germination rate, the present invention has developed a rooting treatment method based on cassava dwarfing treatment and changes in endogenous hormone content, that is, the cassava cuttings are typed according to the ZR / GA value, and then different exogenous hormones are selected as rooting agents according to different types, and the cassava is sprayed, which finally significantly improves the rooting rate and germination rate of cassava. This method overcomes the difference in appearance between cassava varieties, does not select appearance indicators such as stem thickness and plant height, reduces the influence between varieties, objectively types the cassava cuttings, and obtains the specific hormones and ratios of the exogenous hormone rooting agents under different types, greatly improves the survival rate of the cassava cuttings, and improves the breeding capacity of the cassava cuttings.

Brief Description of the Drawings

[0019] Figure 1 This is the result of ABA mass concentration in cassava leaves at different cutting planting times after being soaked in paclobutrazol for 2 hours.

[0020] Figure 2 This is the result of ABA mass concentration in cassava leaves at different cutting planting times after being soaked in paclobutrazol for 4 hours.

[0021] Figure 3 This is the result of IAA mass concentration in cassava leaves at different cutting planting times after being soaked in paclobutrazol for 2 hours.

[0022] Figure 4 This is the result of IAA mass concentration in cassava leaves at different cutting planting times after being soaked in paclobutrazol for 4 hours.

[0023] Figure 5 This is the result graph of GA mass concentration in cassava leaves at different cutting planting times after being soaked in paclobutrazol for 2 hours.

[0024] Figure 6 This is the result graph of GA mass concentration in cassava leaves at different cutting planting times after being soaked in paclobutrazol for 4 hours.

[0025] Figure 7 This is the ZR mass concentration result of cassava leaves at different cutting planting times after being soaked in paclobutrazol for 2 hours.

[0026] Figure 8This is the ZR mass concentration result of cassava leaves at different cutting planting times after being soaked in paclobutrazol for 4 hours. [Specific implementation method]

[0027] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0028] Any feature disclosed in this specification (including any appended claims and abstract), unless otherwise stated, is merely an example of a series of equivalent or similar features.

[0029] Embodiment 1:

[0030] This embodiment is a method for studying endogenous hormones in cassava, which is as follows:

[0031] Different varieties of cassava: variety 1 (Guire 10), variety 2 (Guire 11) and variety 3 (Guire 13) were taken as research objects to study the changes of endogenous hormones such as abscisic acid (ABA), indoleacetic acid (IAA), gibberellin (GA) and zeatin riboside (ZR) under the treatment of exogenous paclobutrazol.

[0032] According to the reference, 20 mg / L paclobutrazol was used to soak the cuttings of three different cassava varieties for 2 hours and 4 hours respectively. The cuttings that were not soaked were used as the CK group. The same planting management method was then used. On the 15th day after the cuttings were planted, leaves were picked every 5 days to test the changes in abscisic acid (ABA), indoleacetic acid (IAA), gibberellin (GA) and zeatin riboside (ZR) in the leaves; the CK group took the average value of the tests of each variety. Figure 1-Figure 8 shown.

[0033] As can be seen from the figure, when paclobutrazol was soaked for 2 hours, the ABA content in the leaves on the 20th, 25th, 30th and 35th days was equivalent to that in the CK group, the IAA content was significantly lower than that in the CK group, the GA content was significantly lower than that in the CK group, and the ZR content was significantly higher than that in the CK group. When paclobutrazol was soaked for 4 hours, the ABA content in the leaves on the 20th, 25th, 30th and 35th days was significantly lower than that in the CK group, the IAA content was equivalent to that in the CK group, the GA content was significantly lower than that in the CK group, and the ZR content was significantly higher than that in the CK group. In summary, the influence trend of paclobutrazol soaking time on the two endogenous hormones GA and ZR in cassava leaves remained unchanged. In subsequent experiments, these two endogenous hormones can be considered as indicators for adding exogenous rooting agents.

[0034] Based on the above research results, the results of calculating ZR / GA are shown in Table 1:

[0035] Table 1 ZR / GA values ​​of various varieties at different stages after paclobutrazol treatment

[0036]

[0037] As can be seen from Table 1, after paclobutrazol immersion treatment, endogenous hormones changed and the ratio was very different from that of the CK group; from the ratio point of view, the ZR / GA value of each variety showed a decreasing relationship.

[0038] In addition, the plant height and stem diameter of each treated seedling were recorded starting from 15 days after planting, and the stem height ratio was calculated, where stem height ratio = (stem diameter on that day / seedling plant height) × 100%. The stem height ratios of each experimental group were counted, and the average stem height ratio of several varieties was calculated for the CK group, where plant height was the height from the soil surface to the growth point, and stem diameter was the main stem diameter 5 cm from the soil surface. The specific results are shown in Table 2.

[0039] Table 2 Height-to-stem ratio of seedlings of different varieties at different stages after paclobutrazol treatment

[0040]

[0041] From Table 2, we can see that the higher the stem-to-height ratio, the thicker the stem of the seedling and the shorter the plant.

[0042] In addition, the germination rate and rooting rate of the seedlings were observed and calculated. The calculation formula of the germination rate was: germination rate = (number of germinating plants / number of cuttings) × 100%; the calculation formula of the rooting rate was: rooting rate = (number of rooting plants / number of cuttings) × 100%. The average values ​​of several varieties were taken for the CK group, as shown in Table 3.

[0043] Table 3 Germination rate and rooting rate of seedlings of different varieties at different stages after paclobutrazol treatment (%)

[0044]

[0045] Combining Table 2 and Table 3, the higher the stem height ratio, the thicker the stem of the seedling, the shorter the plant, and the easier it is to germinate and take root. Combining Table 1 and Table 3, when the paclobutrazol is soaked, the endogenous hormone changes, which will affect the germination rate and rooting rate of cassava. On the whole, when the ZR / GA value reaches below 2.0 and above 1.5 for the first time, the germination rate and rooting rate can reach more than 90%. Therefore, in order to accelerate the germination and rooting of cassava, the ZR / GA value in the leaves can be determined in advance, and then the growth and colonization of cassava seedlings can be promoted by spraying exogenous hormones.

[0046] Embodiment 2:

[0047] According to the analysis results of Example 1, the applicant summarized the following method for adjusting the amount of exogenous hormone application based on the ZR / GA value of cassava leaves, as follows:

[0048] (1) 20 mg / L paclobutrazol was used to immerse the cuttings of three different cassava varieties for 2 h and 4 h respectively;

[0049] On the 5th day after cassava cuttings were planted, the contents of gibberellin (GA) and zeatin riboside (ZR) in the leaves were tested, and the ZR / GA value was calculated. The cassava seedlings were classified according to the ZR / GA value, as follows:

[0050] Type I seedlings: 1.5≤ZR / GA≤2.0

[0051] Type II seedlings: 2.0<ZR / GA

[0052] Type III seedlings: ZR / GA<1.5

[0053] Then, according to the above classification, different concentrations of exogenous hormones in Table 4 were sprayed on the 5th and 10th days, and the rooting rate and germination rate of cassava cuttings were calculated on the 15th day, as shown in the following table:

[0054] Table 4

[0055]

[0056] As can be seen from Table 4, type I seedlings (1.5≤ZR / GA≤2.0) do not require additional addition of exogenous hormones, and the addition of exogenous hormones GA, IAA or NAA will inhibit the germination and rooting of seedlings to varying degrees.

[0057] In type II seedlings (2.0<ZR / GA), the increase of exogenous hormones GA and IAA will affect the rooting and germination of seedlings. When the concentration of GA is 4mM or IAA is also 4mM, the rooting and germination rates of seedlings can reach more than 90%.

[0058] In type III seedlings (ZR / GA<1.5), the use of exogenous hormones GA, IAA and NAA will affect the rooting and germination of seedlings. When the GA concentration reaches 2-4mM, IAA reaches 4mM or NAA concentration reaches 2mM, the rooting and germination rates of seedlings can reach more than 90%.

[0059] Taking the above factors into consideration, orthogonal tests were conducted on type II and type III seedlings, as follows:

[0060] Orthogonal experiment on type II seedlings: An orthogonal experimental design was used to study the effects of the concentrations of exogenous hormones GA and IAA on type II seedlings. The orthogonal experimental factor levels are shown in Table 5. The orthogonal experimental results of the rooting rate and germination rate of type II seedlings are shown in Table 6.

[0061] Table 5 Orthogonal test factor levels of the effects of exogenous hormones GA and IAA on type II seedlings

[0062] level GA addition amount mM (A factor) IAA addition amount mM (B factor) 1 4 4 2 6 5 3 8 6

[0063] The experimental results obtained according to the above factor levels are shown in Table 6:

[0064] Table 6 Orthogonal test results

[0065] Test No. A Factor B Factor Germination rate / % Rooting rate / % 1 1 1 80.24 82.14 2 1 2 84.55 88.67 3 1 3 90.25 94.21 4 2 1 90.15 95.36 5 2 2 91.25 92.01 6 2 3 86.35 89.26 7 3 1 76.14 78.65 8 3 2 70.58 76.39 9 3 3 83.65 89.24

[0066] It can be seen from Table 6 that when the amount of exogenous hormone applied is "4-6 mM GA + 4-6 mM IAA", the germination rate and rooting rate of type II seedlings can reach 90%.

[0067] Orthogonal experiment on type III seedlings: An orthogonal experimental design was used to study the effects of the concentrations of exogenous hormones GA, IAA and NAA on type III seedlings. The levels of orthogonal experimental factors are shown in Table 7. The orthogonal experimental results of the rooting rate and germination rate of type II seedlings are shown in Table 8.

[0068] Table 7 Orthogonal test factor levels of the effects of exogenous hormones GA, IAA and NAA on type III seedlings

[0069]

[0070] The experimental results obtained according to the above factor levels are shown in Table 8:

[0071] Table 8 Orthogonal test results

[0072] Test No. A Factor B Factor Factor C Germination rate / % Rooting rate / % 1 1 1 1 73.36 76.87 2 1 2 2 91.25 94.68 3 1 3 3 92.36 94.21 4 2 1 2 94.15 95.36 5 2 2 3 63.47 70.314 6 2 3 1 89.21 90.34 7 3 1 3 90.14 93.14 8 3 2 1 75.36 79.18 9 3 3 2 77.26 78.64

[0073] It can be seen from Table 8 that when the amount of exogenous hormone applied is "2-6 mM GA + 2-6 mM IAA + 2-3 mM IAA", the germination rate and rooting rate of type III seedlings can reach 90%.

[0074] In summary, type I seedlings do not require additional exogenous hormones, while type II seedlings need to be sprayed with 4mM GA or 4mM IAA or 44-6mM GA + 4-6mM IAA on the 5th and 10th days after cutting, respectively; type III seedlings need to be sprayed with 2-4mM GA or 4mM IAA or 2mM NAA or 2-6mM GA + 2-6mM IAA + 2-3mM IAA on the 5th and 10th days after cutting, respectively.

[0075] In summary, after the cassava cuttings of the present application are soaked in paclobutrazol, the cassava is typed according to the ZR / GA ratio, and then different exogenous hormones are applied in a matching manner, which effectively overcomes the influence of factors such as different varieties and different soaking times on the endogenous hormones of the cassava cuttings. By using exogenous hormones after simple typing treatment, the amount of addition is more accurate and scientific, which can provide new research ideas for the dwarf cutting propagation process of cassava, and effectively accelerate the breeding and utilization of excellent cassava asexual lines.

[0076] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for improving the quality of cassava cuttings based on a dwarfing agent, characterized in that: The method comprises the following steps: after treating cassava cutting seedlings with a dwarfing agent, determining the GA and ZR contents in cassava leaves, and calculating a ZR / GA value; when 1.5≤ZR / GA≤2.0, the cassava cutting seedlings are classified as type I seedlings; when 2.0<ZR / GA, the cassava cutting seedlings are classified as type II seedlings; when ZR / GA<1.5, the cassava cutting seedlings are classified as type III seedlings; and different exogenous hormones are selected according to the above classifications and sprayed onto the cutting seedlings.

2. The method according to claim 1, characterized in that The dwarfing agent is paclobutrazol.

3. The method according to claim 1, characterized in that The type I seedlings do not need additional application of exogenous hormones, the exogenous hormones applied to the type II seedlings are IAA and / or GA; the exogenous hormones applied to the type III seedlings are GA, IAA and / or NAA.

4. The method according to claim 3, characterized in that The exogenous hormone concentration applied to the type II seedlings is 4 mM GA; or 4 mM IAA; or 44-6 mM GA and 4-6 mM IAA.

5. The method according to claim 3, characterized in that: The exogenous hormone concentration applied to the type III seedlings is 2-4 mM GA; or 4 mM IAA; or 2 mM NAA; or 2-6 mM GA, 2-6 mM IAA and 2-3 mM IAA.

6. The method according to claim 2, characterized in that The concentration of paclobutrazol is 20 mg / L.

7. The method according to claim 2, characterized in that The paclobutrazol is applied by soaking the cassava cuttings for 2-4 hours.

8. The method according to claim 1, characterized in that The time for spraying the exogenous hormone is the 5th and 10th day after cutting planting.

9. A method for evaluating the germination rate and / or rooting rate of cassava cuttings based on a dwarfing agent, characterized in that: The method comprises the following steps: after treating the cassava cuttings with a dwarfing agent, determining the GA and ZR contents in the cassava leaves, and calculating the ZR / GA value; when 1.5≤ZR / GA≤2.0, the rooting rate and germination rate of the cassava cuttings are both greater than 90%.

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