Methods for Improving the Quality of Cassava Cuttings Based on Dwarfing Agents

Abstract

This invention relates to the field of cassava cutting propagation technology, and particularly to a method for improving the quality of cassava cuttings based on dwarfing agents. This invention uses dwarfing agents to treat cassava cuttings, and then studies the changes in endogenous hormones in the leaves of cassava cuttings after adding the dwarfing agent. It was discovered that the ZR / GA ratio can be used as an indicator for early evaluation of the rooting and germination rates of cassava cuttings. We found that when 1.5 ≤ ZR / GA ≤ 2.0, the rooting and germination rates of cassava cuttings are both greater than 90%. Based on this pattern, cassava cuttings are categorized, and then different exogenous hormones are selected as rooting agents according to different categories. This reduces the influence between varieties, objectively categorizes cassava cuttings, and determines the specific hormones and ratios of exogenous hormone rooting agents under different categories, greatly improving the survival rate and propagation capacity of cassava cuttings.

Description

[Technical Field]

[0001] This invention relates to the field of cassava cutting propagation technology, and particularly to a method for improving the quality of cassava cuttings based on dwarfing agents. [Background Technology]

[0002] Cassava (Manihot esculenta Crantz) is one of the world's three major tuber crops (cassava, potato, and sweet potato). Originally from Brazil, it is now widely cultivated in tropical regions worldwide. It is one of Guangxi's main economic crops; the tuberous roots of cassava are rich in starch, making them an excellent raw material for industrial starch production.

[0003] In the common cultivation of cassava, cutting propagation is a frequently used asexual reproduction method. Improving the quality of cassava seedlings, especially their germination and rooting rates, is the most crucial factor in cutting propagation. Current research has found that the thicker the cassava cutting, the higher its germination and rooting rates. Existing techniques often select thicker cassava stems for cutting propagation. However, in actual breeding, some varieties tend to have relatively thin stems. Existing techniques include using dwarfing agents to increase seedling thickness. Based on this background, our research group also considered using dwarfing agents to treat seedlings to obtain thicker seedlings and improve the quality of cuttings.

[0004] However, in practical work, we have found that there are many varieties of cassava, and different varieties have different appearances, stem diameters, plant heights, and other indicators. Evaluating whether the dwarfing agent applied to the seedlings is sufficient and whether the dwarfing time is adequate often requires waiting until the cassava has rooted, sprouted, and even grown into a mature plant before a comprehensive judgment can be made. This results in a very long experimental cycle during the application of dwarfing agents. In our practical work, we found that after the application of dwarfing agents, the endogenous hormones in cassava leaves changed rapidly and significantly compared to the control group. Therefore, if we can study the changes in endogenous hormones in cassava leaves after the application of dwarfing agents and adjust the timing and dosage of rooting agents based on this pattern, we can greatly shorten our experimental time and effectively improve the germination and rooting rates of our cuttings, further enhancing 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 enhance the quality of the cuttings, this application studies the changes in endogenous hormones under the condition of applying the dwarfing agent paclobutrazol, and uses this pattern to classify cassava cuttings, applying different exogenous hormone-based rooting agents to accurately, objectively and effectively improve the quality of cassava cuttings.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for improving the quality of cassava cuttings based on dwarfing agents: The method involves treating cassava cuttings with dwarfing agents, measuring the GA and ZR content in cassava leaves, and calculating the ZR / GA value; when 1.5 ≤ ZR / GA ≤ 2.0, the cassava cuttings are classified as Type I seedlings; when 2.0 < ZR / GA, they are classified as Type II seedlings; when ZR / GA < 1.5, they are classified as Type III seedlings; and different exogenous hormones are sprayed onto the cuttings according to the above classification.

[0008] Furthermore, the dwarfing agent is paclobutrazol.

[0009] Furthermore, the type I seedlings do not require additional exogenous hormones, the type II seedlings are treated with exogenous hormones of IAA and / or GA, and the type III seedlings are treated with exogenous hormones of GA, IAA and / or NAA.

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

[0011] Furthermore, the exogenous hormones applied to the type III seedlings are 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 cassava cuttings for 2-4 hours.

[0014] Furthermore, the exogenous hormones are sprayed on the 5th and 10th days after the cuttings are planted.

[0015] The present invention also includes a method for evaluating the germination rate and / or rooting rate of cassava cuttings based on dwarfing agents. The method involves treating cassava cuttings with dwarfing agents, measuring the GA and ZR content in cassava leaves, and calculating the ZR / GA value. When 1.5 ≤ ZR / GA ≤ 2.0, the rooting rate and germination rate of cassava cuttings are both greater than 90%.

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

[0017] 1. This invention uses a dwarfing agent to dwarf cassava cuttings, effectively increasing their thickness. Simultaneously, by studying the changes in endogenous hormones in the leaves of cassava cuttings after adding the dwarfing agent, it was discovered that the ZR / GA ratio can be used as an indicator for early evaluation of cassava rooting and germination rates. We found that when 1.5 ≤ ZR / GA ≤ 2.0, the rooting and germination rates of cassava cuttings are both greater than 90%.

[0018] 2. Based on the patterns of cassava endogenous hormones, dwarfing agents, rooting rate, and germination rate, this invention develops a rooting treatment method based on cassava dwarfing treatment and changes in endogenous hormone content. Specifically, cassava cuttings are categorized according to their ZR / GA values. Then, different exogenous hormones are selected as rooting agents for different categories and sprayed onto the cassava plants. This significantly improves the rooting and germination rates of cassava. This method overcomes the differences in morphology between cassava varieties by not selecting morphological indicators such as stem diameter and plant height, reducing the influence between varieties. It objectively categorizes cassava cuttings and determines the specific hormones and ratios of exogenous hormone rooting agents under different categories, greatly improving the survival rate and propagation capacity of cassava cuttings. [Attached Image Description]

[0019] Figure 1 The graph shows the ABA concentration of cassava leaves after soaking in paclobutrazol for 2 hours at different cutting planting times.

[0020] Figure 2 The graph shows the ABA concentration of cassava leaves after soaking in paclobutrazol for 4 hours at different cutting planting times.

[0021] Figure 3 The graph shows the IAA concentration of cassava leaves after soaking in paclobutrazol for 2 hours at different cutting planting times.

[0022] Figure 4 The graph shows the IAA concentration of cassava leaves after soaking in paclobutrazol for 4 hours at different cutting planting times.

[0023] Figure 5 The graph shows the GA concentration of cassava leaves after soaking in paclobutrazol for 2 hours at different cutting planting times.

[0024] Figure 6 The graph shows the GA concentration of cassava leaves after soaking in paclobutrazol for 4 hours at different cutting planting times.

[0025] Figure 7 The ZR concentration of cassava leaves after soaking in paclobutrazol for 2 hours at different cutting planting times is shown in the figure.

[0026] Figure 8The ZR concentration results of cassava leaves soaked in paclobutrazol for 4 hours at different cutting planting times are shown in the figure. [Specific implementation method]

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

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

[0029] Example 1:

[0030] This embodiment describes a method for studying endogenous hormones in cassava, as detailed below:

[0031] Using different cassava varieties—Variety 1 (Guire 10), Variety 2 (Guire 11), and Variety 3 (Guire 13)—as research subjects, this study investigated the changes in endogenous hormones—abscisic acid (ABA), indoleacetic acid (IAA), gibberellin (GA), and zeatin nucleoside (ZR)—under exogenous paclobutrazol treatment.

[0032] References indicate that paclobutrazol at a concentration of 20 mg / L was used to soak cuttings of three different cassava varieties for 2 hours and 4 hours, respectively. Cuttings without soaking were used as the control group (CK). All cuttings were planted and managed using the same method. On day 15 post-planting, leaves were harvested every 5 days to test changes in abscisic acid (ABA), indoleacetic acid (IAA), gibberellin (GA), and zeatin nucleoside (ZR). The average values ​​of the tests for each variety were used in the CK group. Details are as follows... Figures 1-8 As shown.

[0033] As shown in the figure, after 2 hours of paclobutrazol soaking, the ABA content in leaves on days 20, 25, 30, and 35 was comparable to the control group (CK), while the IAA and GA content were significantly lower, and the ZR content was significantly higher. After 4 hours of paclobutrazol soaking, the ABA content in leaves on days 20, 25, 30, and 35 was significantly lower than the CK, while the IAA content was comparable to the CK, the GA content was significantly lower, and the ZR content was significantly higher. In summary, the paclobutrazol soaking time did not significantly affect the levels of GA and ZR, the two endogenous hormones, in cassava leaves. In future experiments, these two endogenous hormones could be considered as indicators for the addition of exogenous rooting agents.

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

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

[0036]

[0037] As shown in Table 1, the endogenous hormone levels changed after paclobutrazol soaking treatment, and the ratio was significantly different from that of the CK group; in terms of the ratio, the ZR / GA values ​​of each variety showed a decreasing relationship.

[0038] In addition, starting 15 days after planting, the plant height and stem diameter of each treatment seedling were recorded, and the stem height ratio was calculated. The stem height ratio was calculated as (stem diameter on the day / plant height) × 100%. The stem height ratio of each experimental group was statistically analyzed, and the average stem height ratio of several varieties in the CK group was calculated. The plant height is the height from the soil surface to the growing point, and the stem diameter is the diameter of the main stem at 5 cm from the soil surface. The specific results are shown in Table 2.

[0039] Table 2. Stem height ratio of seedlings of different varieties at different growth stages after paclobutrazol treatment.

[0040]

[0041] As shown in Table 2, the higher the stem-to-height ratio, the thicker the stem of the seedling and the shorter the plant.

[0042] In addition, the budding rate and rooting rate of the seedlings were observed and calculated. The budding rate was calculated as follows: budding rate = (number of budding plants / number of cuttings) × 100%; the rooting rate was calculated as follows: rooting rate = (number of rooted 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 Tables 2 and 3, a higher stem-to-height ratio indicates thicker stems and shorter plants, making them easier to germinate and root. Combining Tables 1 and 3, paclobutrazol treatment alters endogenous hormone levels, affecting cassava germination and rooting rates. Overall, when the ZR / GA value first reaches below 2.0 but above 1.5, germination and rooting rates can reach over 90%. Therefore, to accelerate cassava germination and rooting, the ZR / GA value in the leaves can be measured in advance, and then exogenous hormones can be sprayed to promote cassava seedling growth and establishment.

[0046] Example 2:

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

[0048] (1) The cuttings of three different cassava varieties were soaked in 20 mg / L paclobutrazol for 2 h and 4 h respectively;

[0049] On the 5th day after cassava cuttings were planted, the contents of gibberellin (GA) and zeatin nucleoside (ZR) in the leaves were tested, and the ZR / GA value was calculated. The cassava seedlings were then categorized based on the ZR / GA value, as detailed below:

[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, based on the above classification, different concentrations of exogenous hormones (as shown in Table 4) were sprayed on days 5 and 10. The rooting rate and budding rate of the cassava cuttings were calculated on day 15, as shown in the table below:

[0054] Table 4

[0055]

[0056] As shown in Table 4, Type I seedlings (1.5≤ZR / GA≤2.0) do not require additional exogenous hormones. Adding exogenous hormones such as GA, IAA, or NAA will inhibit the budding 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 sprouting of seedlings. When the concentration of GA is 4 mM or IAA is also 4 mM, the rooting and sprouting rates of seedlings can reach more than 90%.

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

[0059] Taking into account the above factors, an orthogonal experiment was conducted on type II and type III seedlings, as detailed below:

[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 levels of factors in the orthogonal experiment are shown in Table 5, and the results of the orthogonal experiment on the rooting rate and germination rate of type II seedlings are shown in Table 6.

[0061] Table 5. Factor levels in the orthogonal experiment on the effects of exogenous hormones GA and IAA on type II seedlings.

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

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

[0064] Table 6 Results of the orthogonal experiment

[0065] Test No. Factor A Factor B 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] As can be seen from Table 6, 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 factors in the orthogonal experiment are shown in Table 7. The results of the orthogonal experiment on the rooting rate and germination rate of type II seedlings are shown in Table 8.

[0068] Table 7. Factor levels in the orthogonal experiment on the effects of exogenous hormones GA, IAA, and NAA on type III seedlings.

[0069]

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

[0071] Table 8 Results of the orthogonal experiment

[0072] Test No. Factor A Factor B 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] As can be seen from Table 8, when the amount of exogenous hormone applied is "2-6mM GA + 2-6mM IAA + 2-3mM 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 require spraying with 4mM GA, 4mM IAA, or 44-6mM GA + 4-6mM IAA on the 5th and 10th days after cutting, respectively; Type III seedlings require spraying with 2-4mM GA, 4mM IAA, 2mM NAA, or 2-6mM GA + 2-6mM IAA + 2-3mM IAA on the 5th and 10th days after cutting, respectively.

[0075] In summary, by using cassava cuttings from this application for paclobutrazol soaking, and then tying the cassava based on the ZR / GA ratio, and subsequently applying different exogenous hormones, the influence of different varieties and soaking times on the endogenous hormones of cassava cuttings can be effectively overcome. The simple tying process followed by the application of exogenous hormones allows for more precise and scientific dosage, providing new research ideas for dwarfing cassava cutting propagation and effectively accelerating the breeding and utilization of superior cassava clones.

[0076] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for improving the quality of cassava cuttings based on dwarfing agents, characterized in that, The method involves treating cassava cuttings with a dwarfing agent, measuring the GA and ZR content in the cassava leaves, and calculating the ZR / GA value. When 1.5 ≤ ZR / GA ≤ 2.0, the cassava cuttings are classified as Type I seedlings; when 2.0 < ZR / GA, they are classified as Type II seedlings; and when ZR / GA < 1.5, they are classified as Type III seedlings. Based on the above classification, different exogenous hormones are selected and sprayed onto the cuttings. The dwarfing agent is paclobutrazol; the concentration of paclobutrazol is 20 mg / L; and the paclobutrazol is applied by soaking the cassava cuttings for 2-4 hours.

2. The method according to claim 1, characterized in that, Type I seedlings do not require additional exogenous hormones, Type II seedlings are treated with exogenous hormones of IAA and / or GA, and Type III seedlings are treated with exogenous hormones of GA, IAA and / or NAA.

3. The method according to claim 2, characterized in that, The exogenous hormones applied to the type II seedlings were 4 mM GA; or 4 mM IAA; or 44-6 mM GA and 4-6 mM IAA.

4. The method according to claim 2, characterized in that, The exogenous hormones applied to the Type III seedlings are 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.

5. The method according to claim 1, characterized in that, The exogenous hormones were sprayed on the 5th and 10th days after the cuttings were planted.

6. A method for evaluating the germination rate and / or rooting rate of cassava cuttings based on dwarfing agents, characterized in that, The method involves treating cassava cuttings with a dwarfing agent, measuring the GA and ZR content in 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%. The dwarfing agent is paclobutrazol. The concentration of paclobutrazol is 20 mg / L. The paclobutrazol is applied by soaking the cassava cuttings for 2-4 hours.

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