Artificial pollination method for improving selfing effect of alfalfa

Abstract

The invention belongs to the technical field of alfalfa selfing planting, and particularly relates to an artificial pollination method for improving the selfing effect of alfalfa, which comprises the following steps: bagging when the carina of the alfalfa inflorescence is not opened from the squaring stage of alfalfa; when the flower buds grow to the fourth stage, artificial pollination is carried out every 3-4 days; when pods grow to be brown, the seeds are harvested. According to the method, bagging is carried out in the squaring stage, bloomed flowers and immature flowers at the top ends of inflorescences do not need to be removed, and then the labor cost is reduced; artificial pollination is carried out when the flower buds grow to the fourth stage, multiple times of selfing pollination can be achieved, then the selfing seed bearing amount is effectively increased, and the pollination success rate is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of alfalfa self-pollination planting technology, and particularly relates to an artificial pollination method for improving the self-pollination effect of alfalfa. Background Art

[0002] Alfalfa (Medicago sativa L.) is a perennial herbaceous plant of the genus Medicago, Leguminosae, with an erect, clumping or creeping stem in a quadrangular shape with many branches; the stipules are large, ovate-lanceolate, and the leaflets are obovate-oblong; the flowers are family-like racemes; the pedicels are bell-shaped, and the corolla is purple; the fruits are spiral-shaped, brown when ripe; the seeds are small and smooth, yellow or brown. Alfalfa is known as the king of forage grasses, not only with high yield, but also with excellent grass quality, and is a favorite food of all kinds of livestock and poultry.

[0003] Alfalfa itself is a heterozygote. Most alfalfa varieties are in a state of random mating equilibrium. The characteristics and agronomic value of alfalfa are maintained by the constant frequency of genes and genotypes between generations. The synthetic alfalfa variety conforms to the law of population genetics. The inflorescence of alfalfa is a racemose inflorescence. The order of flowering is from the bottom of the inflorescence to the top. Therefore, the flowering time of different plants, different branches of the same plant, different inflorescences of the same branch, and different single flowers of the same inflorescence are not synchronized.

[0004] Alfalfa has serious self-incompatibility and self-depression characteristics, so it is very difficult to establish alfalfa inbred lines or homozygous lines, which seriously hinders the improvement of alfalfa production potential. At present, the methods of alfalfa self-pollination include natural self-pollination, bagging self-pollination, artificial assisted self-pollination, self-pollination bagging in the initial flowering period, self-pollination bagging in the full flowering period, and self-pollination in a net room. The artificial assisted self-pollination method usually performs artificial pollination in the third stage of alfalfa bud development. However, during the process from the first stage to the third stage of bud development, the anthers in the buds have not split, and the pollen is not mature at this time and is still wrapped in the anthers. Therefore, if artificial pollination is performed in the third stage, the pollen cannot fall well on the pistil, which in turn affects the self-pollination effect. Summary of the invention

[0005] In order to solve the problem of poor self-pollination effect of alfalfa in the prior art, the present invention provides an artificial pollination method for improving the self-pollination effect of alfalfa. By performing artificial pollination when the flower buds develop to the fourth stage, pollen can fall into the pistil, thereby improving the self-pollination effect of alfalfa and being used to establish an alfalfa inbred line or a homozygous line.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] An artificial pollination method for improving the self-pollination effect of alfalfa comprises the following steps:

[0008] Bag treatment is carried out from the bud stage of alfalfa to the period when the keel petals of the alfalfa inflorescence have not yet opened;

[0009] When the flower bud develops to the fourth stage, artificial pollination is performed 3 to 5 times, with an interval of 3 to 4 days between each artificial pollination; the fourth stage is when the keel petal has the ventral surface of the standard petal appearing, but the standard petal has not yet turned upward;

[0010] When the pods grow to brown, harvest them.

[0011] The present invention performs artificial pollination when the flower buds develop to the fourth stage, at which time the anthers split to release pollen, and some of the pollen are already mature. The pollen can not only fall on the pistil more easily during artificial pollination at this stage, thereby improving the success rate of artificial pollination, but also can still maintain a relatively high success rate of pollination after multiple artificial pollinations, thereby being used to establish an alfalfa inbred line or a homozygous line, and obtaining high-quality inbred alfalfa germplasm.

[0012] In another preferred embodiment, the unopened keel petal of the alfalfa inflorescence specifically means that half of the alfalfa inflorescence blooms to the point where the standard petal is fully opened but the keel petal is not opened.

[0013] In another preferred embodiment, the specific process of artificial pollination is as follows:

[0014] The inflorescence is squeezed along the horizontal and vertical directions of the flower buds to open the keel petals of alfalfa and allow the pollen to fall onto the pistil. The artificial pollination method of opening the keel petals in the horizontal and vertical directions can achieve multiple self-pollination, thereby effectively increasing the self-pollination seed yield and the pollination success rate.

[0015] In another preferred embodiment, the extrusion is performed 3 to 4 times.

[0016] In another preferred embodiment, the time of artificial pollination is from 9 am to 5 pm.

[0017] In another preferred embodiment, a mesh bag is used for bagging.

[0018] In another preferred embodiment, the mesh number of the mesh bag is 40-60 meshes.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention carries out artificial pollination through flowering 4 phases, at which time the anthers crack and scatter pollen, and some pollen are already mature. At this time, the pollen can not only fall on the pistil more easily, but also improve the artificial pollination success rate, and after carrying out artificial pollination for many times, a higher pollination success rate can still be maintained. And by bagging in the budding stage, it is not necessary to remove the opened flowers and the immature flowers at the top of the inflorescence, thereby reducing labor costs. The selfing method in the present invention can be used to establish an alfalfa inbred line, create alfalfa germplasm and expand and enrich alfalfa germplasm resources, and also provide new excellent parents for cultivating new excellent alfalfa varieties. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 S is obtained by self-pollination 1 Generation plant population diagram.

[0022] Figure 2 S is obtained by self-pollination 2 Generation plant population diagram. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] Unless otherwise specified, the experimental methods described in the following examples are all conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0025] At present, the methods of alfalfa self-pollination include natural self-pollination, bagging self-pollination, artificial assisted self-pollination, bagging self-pollination in the early flowering period, bagging self-pollination in the full flowering period, and self-pollination in a net room. The self-pollination fruit set rate of these alfalfa self-pollination methods is low and cannot meet the requirements for establishing alfalfa inbred lines.

[0026] The development state of the flower bud is divided into 5 stages, namely, in the first stage, the petals are completely wrapped by the calyx, in the second stage, the petals have appeared between the calyx lobes, but the length has not yet exceeded the sepals; in the third stage, the petals are more than 2 mm longer than the calyx, but the keel is still wrapped by the standard petal; in the fourth stage, the keel has appeared on the ventral side of the standard, but the standard has not yet turned upward; in the fifth stage, the floret opens, the standard turns upward, and the keel is exposed between the wing petals. In the prior art, artificial pollination is usually performed in the third stage of flower bud development. However, from the first stage to the third stage of the flower bud, the anthers in the flower buds have not split, and the pollen is not mature at this time and is still wrapped in the anthers. Therefore, if artificial pollination is performed in the third stage, the pollen cannot fall well on the pistil, thereby affecting the self-pollination effect.

[0027] The embodiment of the present invention provides an artificial pollination method for improving the self-pollination effect of alfalfa. Artificial pollination is performed at the fourth stage of the flower buds. At this time, the anthers are cracked to release pollen, and some pollen has matured. At this time, the pollen can not only fall on the pistil more easily, but also improve the success rate of artificial pollination. After multiple artificial pollinations, a high pollination success rate can still be maintained. In addition, the present invention performs bagging from the alfalfa budding stage to when half of the florets of the alfalfa inflorescence bloom until the flag petal is fully opened and the keel petal is not opened, and there is no need to remove the opened flowers and the immature flowers at the top of the inflorescence, which greatly reduces manual labor and reduces labor costs.

[0028] The following is a detailed description of an artificial pollination method for improving the self-pollination effect of alfalfa.

[0029] Example 1

[0030] An artificial pollination method for improving the self-pollination effect of alfalfa comprises the following steps:

[0031] S1. Use 40-mesh mesh bags to isolate the plants from the budding stage to when half of the alfalfa inflorescence has bloomed and the standard petal has fully opened but the keel petal has not opened.

[0032] S2. When the flower buds develop to the fourth stage, wear disposable PE gloves on your hands and gently squeeze the inflorescence three times along the horizontal and vertical directions of the flower buds between 9 am and 5 pm on a sunny day to open the keel petals of the alfalfa florets and cause the pollen to burst out and scatter to the pistil. Artificial pollination is carried out again every three days. A total of three artificial pollinations are carried out in the same mesh bag.

[0033] S3. Wait until the pods grow to brown and then harvest.

[0034] Example 2

[0035] An artificial pollination method for improving the self-pollination effect of alfalfa comprises the following steps:

[0036] S1. Use 60-mesh net bags to isolate the plants from the budding stage to when half of the alfalfa inflorescence has bloomed and the standard petal has fully opened but the keel petal has not opened.

[0037] S2. When the flower buds develop to the fourth stage, wear disposable PE gloves on your hands and gently squeeze the inflorescence four times along the horizontal and vertical directions of the flower buds between 9 am and 5 pm on a sunny day to open the keel petals of the alfalfa florets and cause the pollen to burst out and scatter to the pistil. Artificial pollination can be carried out again every four days. A total of four artificial pollinations can be carried out in the same mesh bag.

[0038] S3. Wait until the pods grow to brown and then harvest.

[0039] Example 3

[0040] An artificial pollination method for improving the self-pollination effect of alfalfa comprises the following steps:

[0041] S1. Use 50-mesh mesh bags to isolate the plants from the budding stage to when half of the alfalfa inflorescence has bloomed and the standard petal has fully opened but the keel petal has not opened.

[0042] S2. When the flower buds develop to the fourth stage, wear disposable PE gloves on your hands and gently squeeze the inflorescence three times along the horizontal and vertical directions of the flower buds between 9 am and 5 pm on a sunny day to open the keel petals of the alfalfa florets and cause the pollen to burst out and scatter to the pistil. Artificial pollination is carried out again every three days. A total of five artificial pollinations are carried out in the same mesh bag.

[0043] S3. Wait until the pods grow to brown and then harvest.

[0044] In order to further illustrate the effect of the present invention, the artificial pollination method in Example 1 is used to obtain alfalfa with a large number of compound leaves, and the specific process is as follows:

[0045] Alfalfa plants with compound leaves ≥5 were selected as parents for cultivation. The specific process is as follows:

[0046] S1. Use 40-mesh mesh bags to isolate the plants from the budding stage to when half of the alfalfa inflorescence has bloomed and the standard petal has fully opened but the keel petal has not opened.

[0047] S2. When the flower buds develop to the fourth stage, wear disposable PE gloves on your hands and gently squeeze the inflorescence three times along the horizontal and vertical directions of the flower buds between 9 am and 5 pm on a sunny day to open the keel petals of the alfalfa florets and cause the pollen to burst out and scatter to the pistil. Artificial pollination is carried out again every three days, and artificial pollination is carried out three times with the same mesh bag.

[0048] S3. Wait until the pods grow to brown, the skin is yellow or yellowish brown, and the seeds are full and hard before harvesting. Harvest at the single plant and single branch level and record. After threshing the collected pods, dry the seeds at room temperature for one month, dry and refrigerate them at 4°C in a refrigerator, treat them in liquid nitrogen for 10 seconds before sowing, take them out and place them at room temperature, and then you can sow them.

[0049] S4. Sow seeds in holes with a plant spacing of 60 cm and a row spacing of 80 cm. When sowing, sow seeds of the same plant in rows according to the branches to which the seeds belong.

[0050] S5. Select alfalfa plants with 5 or more compound leaves and continue to self-pollinate according to the above method to obtain alfalfa seeds with a large number of compound leaves.

[0051] The artificial pollination method described above was used to evaluate the self-pollination of S 1 Generation and S 2 The results of each plant in the generation plant population Figure 1 and Figure 2 As shown. Self-pollination yields S 1 Generation plant population, in S 1 In the first generation of plants, plants with 4, 5, and 7 compound leaves appeared. The results were as follows: Figure 1 Select plants with seven complete compound leaves and continue to use the method in Example 1. 2 In the first generation of plant populations, alfalfa plants with 9, 11, 15, and 16 compound leaves appeared, such as Figure 2 This indicates that the selfing method of the present invention can improve the selfing effect and create new germplasm with compound leaf traits superior to those of the parent.

[0052] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An artificial pollination method for improving the self-pollination effect of alfalfa, characterized in that: The following steps are involved: Bag treatment is carried out from the budding stage of alfalfa to the period when the keel petals of the alfalfa inflorescence have not yet opened; When the flower bud develops to the fourth stage, artificial pollination is performed 3 to 5 times, with an interval of 3 to 4 days between each artificial pollination; the fourth stage is when the keel petal has the ventral surface of the standard petal appearing, but the standard petal has not yet turned upward; When the pods grow to brown, harvest them.

2. The artificial pollination method for improving the selfing effect of alfalfa according to claim 1, characterized in that: The fact that the keel petal of the alfalfa inflorescence has not opened specifically refers to that half of the alfalfa inflorescence has bloomed to the point where the standard petal is fully opened, but the keel petal has not opened.

3. The artificial pollination method for improving the selfing effect of alfalfa according to claim 1, characterized in that: The specific process of the artificial pollination is as follows: The inflorescence is squeezed horizontally and vertically along the flower buds to open the keel of the alfalfa and allow the pollen to fall onto the pistil.

4. The artificial pollination method for improving the selfing effect of alfalfa according to claim 3, characterized in that: The extrusion is performed 3 to 4 times.

5. The artificial pollination method for improving selfing of alfalfa according to claim 1, characterized in that: The time of artificial pollination is from 9 am to 5 pm.

6. The artificial pollination method for improving selfing of alfalfa according to claim 1, characterized in that: Use mesh bags for bagging.

7. The artificial pollination method for improving selfing of alfalfa according to claim 7, characterized in that: The mesh number of the mesh bag is 40 to 60 meshes.

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