Method for increasing fruit setting number of macadamia nuts

Abstract

The invention belongs to the technical field of agricultural planting, and particularly relates to a method for increasing the fruit setting number of macadamia nuts, which comprises the following steps: separating selected macadamia nut female parent and male parent plants by using an insect-proof net before flowering so as to avoid the influence of insects; after the female parents enter a full-bloom stage, selecting sunny weather with the daytime air temperature of 20-30 DEG C and the wind speed of less than 1m / s, cleaning original pollen on styluses of the female parents by using a sterile writing brush, brushing the collected pollen of the male parents on the styluses by using a brush pen for pollination, keeping isolation for 14 days after pollination, and then removing the insect-proof net. The high-affinity pollination combination is screened by combining germplasm such as Guijin No.1, Guijin A4 and Guijin YM26 with pollen viability. The optimal pollination combination is screened by evaluating the affinity of 16 hybrid combinations of 10 germplasms of macadamia nuts. Results show that when A4 is used as a male parent and Guihot No.1 is used as a female parent, the affinity of cross pollination is the highest, the success rate of cross pollination is remarkably improved, the average fruit setting number is remarkably increased, and effective technical support is provided for high-yield cultivation of macadamia nuts.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology, specifically relating to a method for improving macadamia nut yield through artificially controlled hybridization pollination. Macadamia integrifolia The method of counting fruit set is particularly suitable for variety improvement and yield enhancement in commercial planting. Background Technology

[0002] Macadamia nuts ( Macadamia integrifolia Maiden & Betche is a plant of the Proteaceae family native to the tropical rainforests of Australia. It has been selected and promoted for cultivation due to its extremely high nutritional and commercial value.

[0003] Under open pollination conditions, the fruit set rate of macadamia nuts is only 0.1-0.3%. One reason for this low fruit set rate is its self-incompatibility; hybridization can significantly improve fruit set and yield. Macadamia nuts exhibit varying pollinability to different varieties, and suitable pollinator varieties can increase the number of fruits and yield. Studies by Ito et al. found that mixed-planting macadamia trees yielded an average of about 16 kg more per tree annually than monoculture. Therefore, researching and selecting suitable female and male parents for macadamia varieties is of great significance.

[0004] Unfertilized florets of macadamia nuts usually fall off naturally within 1-2 weeks after flowering. During this stage, fruit drop is mainly caused by pollination and fertilization, and the initial fruit set count should be taken after 2 weeks.

[0005] Commonly used methods for determining pollen viability include staining and germination methods. Staining methods are quick and simple, but can result in false positives or false negatives; germination methods do not produce false positives, but germination rates vary under different germination conditions. Macadamia pollen viability is related to factors such as opening time and germplasm. Under open pollination conditions, pollen viability is positively correlated with the initial number of fruits set by the maternal parent. However, the relationship between pollen viability and maternal compatibility among different macadamia germplasms remains unclear. Summary of the Invention

[0006] This invention addresses the technical problems in existing technologies, such as the low natural pollination and fruit set rate of macadamia nuts (<0.3%) and the lack of scientific basis for variety combination screening. It provides an artificially controlled hybridization pollination method based on germplasm selection, which can increase the number of fruits set to an average of more than 21.57 per sequence.

[0007] The technical solution of the present invention is achieved through the following steps: A method to increase the number of macadamia nuts set includes the following steps: (1) Isolation treatment Before flowering, use insect-proof netting to isolate both the macadamia nut mother and father plants to avoid insect damage. (2) Demasking treatment When the mother plant enters its peak flowering period, choose a sunny day with a daytime temperature of 20-30℃ and a wind speed of <1m / s, and use a sterile brush to clean the pollen off the style of the mother plant. (3) Artificial pollination Use a sterilized brush to evenly apply the pre-collected pollen from the male parent to the stigma of the female parent; (4) Post-processing After pollination, maintain insect-proof netting for 14 days.

[0008] Furthermore, the parent plant is Macadamia Nut Cinnamon No. 1 ( Macadamia integrifolia 'Guire 1').

[0009] Furthermore, the parent plant is macadamia nut A4 ( Macadamia integrifolia 'A4').

[0010] Furthermore, the macadamia nut parent trees are mature fruit trees that are 5-7 years old and growing vigorously.

[0011] Furthermore, the insect-proof net is 80-100 mesh, made of polyethylene, and has a light transmittance of ≥85%.

[0012] Furthermore, the peak flowering period is when the number of flowers on a single plant reaches 75%-85% of the total number of flowers.

[0013] Furthermore, the paternal pollen is fresh pollen collected within 12 hours after flowering, with a pollen germination rate ≥28.57%.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention uses germplasm such as Guire 1, A4, and YM26, combined with pollen viability screening, to select suitable pollination combinations. The optimal pollination combination was screened by evaluating the compatibility of 16 hybrid combinations from 10 macadamia germplasms. The results showed that using A4 as the male parent and Guire 1 as the female parent resulted in the highest hybridization pollination compatibility, the highest average number of initial fruits, significantly improved the hybridization pollination success rate, and significantly increased the average number of fruits, providing effective technical support for high-yield macadamia cultivation. Attached Figure Description

[0015] Figure 1 A diagram showing the average number of initial fruits per inflorescence in a hybridization pollination experiment. Figure 2 Assortment diagram for determining macadamia pollen viability using staining method; Figure 3 A bar chart showing the pollen germination rate of macadamia nuts; Figure 4 This is a composite graph showing the correlation between pollen germination rate and average initial fruit set.

[0016] Explanation of key figure labels: Figure 1 In the diagram, A: Rainbow plot of initial fruit count in the hybridization pollination experiment (violin plot + scatter plot + box plot), × represents outlier; B: Rainbow plot of initial fruit count for each hybrid combination (violin plot + scatter plot + box plot), × represents outlier; C: Bar chart of average initial fruit count for each hybrid combination, with Duncan's new multiple range method used for multiple comparisons, and different letters above the bars indicating significant differences. Figure 2 In the figure, A: staining with potassium iodide starch indicator (0.5%); B: staining with TTC staining solution (2%); C: staining with acetic carmine staining solution; Figure D: bar chart of pollen staining rate stained with acetic carmine, the multiple comparison method is Duncan's new multiple range method, and different letters above the bars represent significant differences. Figure 3 In this study, the multiple comparison method used was Duncan's new multiple range method, and different letters above the bars represented significant differences. Figure 4 In the figures, A: Linear regression plot of pollen germination rate and average number of initial fruits, R is the Spearman rank correlation coefficient, p≤0.05 is statistically significant; B: Double Y bar chart of pollen germination rate and average number of initial fruits when using Guire 1 as the female parent; C: Double Y bar chart of pollen germination rate and average number of initial fruits when using YM26 as the female parent. Detailed Implementation

[0017] The technical solution of this invention patent will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0018] 1. Materials and Methods 1.1 Test Materials Five maternal germplasm accessions and ten paternal germplasm accessions were selected to design a total of 16 hybridization combinations, as detailed in Table 1. The experimental plants were planted in the Tropical and Subtropical Germplasm Resource Nursery of the Guangxi South Subtropical Agricultural Research Institute, with a plant spacing of 5×5m, a tree age of 5 years, and the same water and fertilizer management.

[0019] Table 1 Hybridization Experiment Combination Table

[0020] 1.2 Test Methods 1.2.1 Hybrid pollination Before flowering, the macadamia nut mother plant and father plant are isolated with insect-proof netting to avoid the influence of insects; (2) Demasing treatment: When the mother plant enters the peak flowering period, choose a sunny day with daytime temperature of 20-30℃ and wind speed <1m / s, and use a sterile brush to clean the pollen on the stigma of the mother plant; (3) Artificial pollination: Use a sterile brush to evenly apply the pre-collected pollen of the father plant to the stigma of the mother plant; (4) Post-treatment: After pollination, maintain the insect-proof netting isolation for 14 days.

[0021] Average number of fruits set at first time = total number of fruits set / total number of inflorescences 1.2.2 Pollen staining Potassium iodide starch indicator (0.5%), TTC staining solution (0.2%), and acetic carmine staining solution were dropped onto different concave glass slides, shaken off, and allowed to stand for 10 minutes before being observed under a 100x microscope.

[0022] 1.2.3 Pollen germination in vitro The in vitro liquid germination method (10% sucrose: 0.05% boric acid: 0.05% calcium chloride) was used. After dropping the sucrose solution onto a concave glass slide, the stigma containing pollen was gently brought into contact with the solution using tweezers, and the slide was gently stirred to ensure even distribution of the pollen within the droplet. The concave slide was then placed in a petri dish lined with moistened filter paper and covered. After incubation at 24°C for 6 hours, the samples were examined under a 100x microscope. Germination was considered complete when the pollen tube length was greater than twice the diameter of the pollen grain. The number of germinated pollen grains was counted, and the germination rate was calculated.

[0023] Pollen germination rate = (Number of germinated pollen / Number of pollen) × 100% 2. Experimental Results 2.1 Artificial hybridization pollination experiment See results Figure 1 .

[0024] Depend on Figure 1 It can be seen that the number of initial fruits set after artificial hybridization varies considerably among different pollination combinations. The number of initial fruits in this experiment is relatively thick, indicating a relatively concentrated data distribution. The median is 10, with a range of 1-35, and the mode is 8. Figure 1 A). The average number of initial fruits set after artificial hybridization ranged from 6.5 to 21.6. The violin parent of 791(♂)ⓧA4(♀) had the thickest fruit set and the most concentrated distribution, while A4(♂)ⓧGuiRe1(♀) showed the opposite. The median of A4(♂)ⓧGuiRe1(♀) was higher than other combinations, indicating a higher overall number of fruits set, while 791(♂)ⓧA4(♀) showed the opposite. The medians of combinations using YM26 as the female parent were similar, but the distribution widths differed significantly. Figure 1B). A4(♂)ⓧGuire 1(♀) had the highest average initial fruit set, while 791(♂)ⓧA4(♀) had the lowest, representing the best and worst hybrid combinations in this experiment, respectively. The average initial fruit set of hybrid combinations with Guire 1 as the female parent was generally high, while the average initial fruit set of hybrid combinations with YM26 as the female parent showed little difference, indicating that YM26 has a lower selectivity for pollinating trees than other germplasms. When Guire 1 was the female parent, the average initial fruit set of A4 as the male parent was significantly higher than that of other germplasms, while the average initial fruit set of Longbian 9 and 791 as male parents was similar. When YM26 was the female parent, the average initial fruit set of A4 as the male parent was also significantly higher than that of other germplasms, indicating that A4 is suitable as a pollinating germplasm for YM26 and Guire 1.

[0025] 2.2 Macadamia nut germplasm pollen viability See results Figure 2 and Figure 3 .

[0026] Depend on Figure 2 It can be seen that this experiment used three pollen staining methods: potassium iodide starch indicator (0.5%), TTC staining solution (2%), and acetic carmine staining solution. Potassium iodide starch indicator (0.5%) and TTC staining solution (2%) failed to change the color of macadamia pollen from any germplasm, while acetic carmine showed good staining properties for macadamia pollen. Figure 2 A- Figure 2 C). In acetic carmine staining, the staining rate was as high as 83.93% or more, with A4 having the lowest staining rate and JW having the highest staining rate of 99.32%; the staining rates of YM26 and Guire 1 were significantly higher than those of A4, A38, and FS2; there was no difference in staining rate among FS3, Guire 1, JW, YM26, and Longbian 9; there was no difference in staining rate among FS3, Guire 1, and 791; there was no difference in staining rate among A4, A38, and FS2. Figure 2 D).

[0027] Depend on Figure 3 It was found that there were significant differences in pollen germination rates among different macadamia nut germplasms. Among the nine germplasms, Guire 1 had the highest germination rate at 71.94%, followed by Longbian 9 at 65.06% and YM26 at 59.52%. The lowest germination rate was FS2 at 17.14%. The pollen germination rates of Guire 1, Longbian 9, YM26, and 791 were significantly higher than those of other germplasms. There were no significant differences among Guire 1, Longbian 9, and YM26, nor among FS3, A4, A38, and JW. The pattern of pollen germination rates among different germplasms was similar to that of acetic carmine staining.

[0028] 2.3 Correlation analysis between pollen germination rate and average number of initial fruits To investigate the effect of pollen viability on artificial hybridization pollination, this study analyzed the correlation between pollen germination rate and the average number of initial fruits per inflorescence. The results are shown in [Figure number missing]. Figure 4 .

[0029] Depend on Figure 4 The Spearman rank correlation coefficient was 0.09, and the p-value was 0.77, indicating a weak positive correlation between macadamia pollen germination rate and the average number of fruits set at first artificial pollination. However, the evidence to reject the null hypothesis was insufficient. Figure 4 A).

[0030] When YM26 and Guire 1 were used as the female parent, the pattern was observed that the pollen germination rate of the male parent with a high average number of initial fruits after artificial hybridization was not necessarily high. For example, the pollen germination rate of A4 was only 28.57%, but the average number of initial fruits was as high as 21.57 when pollinated with Guire 1 and 12.95 when pollinated with YM26. These were the best pollinating varieties for Guire 1 and YM26, respectively. Figure 4 B Figure 4 C). Correlation analysis of macadamia pollen germination rate and average initial fruit set, as well as analysis of the double "Y" axis bar graph, both showed that the correlation between pollen germination rate and average initial fruit set was low under artificial pollination conditions.

Claims

1. A method for increasing the number of macadamia nuts set, characterized in that, Includes the following steps: (1) Isolation treatment Before flowering, use insect-proof netting to isolate both the macadamia nut mother and father plants to avoid insect damage. (2) Demasking treatment When the mother plant enters its peak flowering period, choose a sunny day with a daytime temperature of 20-30℃ and a wind speed of <1m / s, and use a sterile brush to clean the pollen off the style of the mother plant. (3) Artificial pollination Use a sterilized brush to evenly apply the pre-collected pollen from the male parent to the stigma of the female parent; (4) Post-processing After pollination, maintain insect-proof netting for 14 days.

2. The method according to claim 1, characterized in that, The parent plant is Macadamia Nut Gui Re No.

1.

3. The method according to claim 1, characterized in that, The parent plant is macadamia nut A4.

4. The method according to claim 1, characterized in that, The parent trees are mature fruit trees that are 5-7 years old and growing vigorously.

5. The method according to claim 1, characterized in that, The insect-proof netting is made of polyethylene with a mesh size of 80-100 and a light transmittance of ≥85%.

6. The method according to claim 1, characterized in that, The peak flowering period described in step (2) is when the number of flowers on a single plant reaches 75-85% of the total number of flowers.

7. The method according to claim 1, characterized in that, The male pollen mentioned in step (3) is fresh fresh pollen collected within 12 hours after flowering, with a pollen germination rate ≥28.57%.

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