Summer Palace big fruit elm seed seedling technology
Liu Cong and others
Ulmus macrocarpa Hance is a deciduous tree or shrub of the elm family (Ul -maceae) of the genus Ulmus, which has the characteristics of strong drought tolerance, wide adaptation range and excellent landscape effect, and is a dominant species in many communities. There are many types of natural variations of large elms, from posture (trees, shrubs) to the shape of winged fruits, from leaf size to the number of lateral veins, etc., and it is difficult to find related and stable distinguishing features.
The Big Fruit Elm of the Summer Palace has formed a characteristic plant landscape in the Harmonic Garden, with beautiful tree shape and brilliant autumn colors, which is a colored tree species that "increases color and extends green", as a native tree species in Beijing, with strong adaptability and few diseases and insect pests. There are many methods of seedlings in elm genus, including seed seedlings, root tiller seedlings, hard branch cuttings, young branch cuttings, grafting and tissue culture, among which seed breeding (sexual breeding) is one of the traditional and relatively simple ways of large fruit elm breeding, and it is also the basis of other seedling methods. However, the natural wild state of the large elm seed fullness is different, the germination is uneven, the natural reproduction rate is low, and the research on the large elm is not yet in-depth, which restricts the pace of promotion and application of this characteristic plant. Therefore, this paper takes the Summer Palace Big Fruit Elm as the research object, and adopts refined seedling management measures through the study of its seeds and their seedling technology, so as to provide practical and feasible seedling methods for the rapid breeding of the Big Fruit Elm and provide technical support for large-scale application and promotion.
1 Materials and methods
１． 1 Test material
１． １． 1 Material Select the large elm plants with an age of more than 15 years in the Summer Palace as seed collection trees, and when the wing fruits mature at the end of April and the color changes from green to yellow, the mature but not shedding seeds are picked from the branches as research materials, and stored in the shade in a ventilated place.
１． １． 2 Sowing substrate In order to reasonably control the moisture, temperature and air permeability of the substrate, perlite and grass charcoal soil are selected according to 3 different proportions to form a perlite: grass charcoal soil volume ratio A (1:1), B (3:1), C (5:1) and other 3 substrates, and loaded into a nutrient bowl of 7cm ×8cm for use. Use 0. before planting 2% potassium permanganate solution disinfects the matrix.
１． 2 Experimental research and design
１． ２． 1 Seed basic data The mature seeds were randomly selected for seed size measurement, 100 seeds per group, repeated 6 times, 1 000 mature seeds were selected for 1,000 mass weighing, and the fullness rate of the fruit was counted and repeated 6 times.
１． ２． 2 Seed germination Select plump seeds that are not decaying and not eaten for seedling testing. The seeds are planted in three different types of substrates, such as A, B and C, placed in a solar greenhouse, watered thoroughly, and the germination is observed every day, and the length of the tapester is measured to record the data.
According to the RC-4HC temperature and humidity recorder data, the average daily temperature in the greenhouse during the test was 23. 7 °C, with an average humidity of 53%RH, meets the seed germination conditions.
１． 3 Transplanting and post-management
After the seedlings are higher than 50 cm in the same year, they can be transplanted to the nursery, and the later management includes fertilizer and water management, weeding and shaping, overwintering management and pest control.
2 Results and analysis
２． 1 Seed characteristics
The ripe fruit of the Summer Palace large elm is a winged fruit, wide inverted ovate, round, nearly round or wide oval, the core part is located in the middle of the wing fruit, the succumb flower is bell-shaped, and the size of the wing fruit is much larger than that of other elm species. Small wild animals (such as squirrels) in the Summer Palace like to eat their seed kernels, so that a large number of fruits fall off in advance, and the fruits picked on the branches are intact. From the measurement results, it can be seen that the size of the large elm fruit is determined by (1. ６ｃｍ×２． ２ｃｍ ） ～ （ ２． ９ｃｍ×３． 8cm) varies, most in 2. ３ｃｍ×３． About 1 cm, the seeds of the removed wings are heart-shaped, vary in size, and generally have a grain size of about 3 to 6 mm. This is consistent with previous studies in which the large elm leaf phenotype has a very significant correlation between and within populations, and there are rich variations within and between populations.
The mass of 1,000 grains of the large elm fruit of the Summer Palace is 57. ７３～６１． 38g, the average is (59. ２３±１． ４１ ） ｇ 。 The fullness rate of large elm fruits picked on branches is 79%, while the fullness rate of seeds that fall off early is less than 10%, which is related to animal feeding and short growth time of most fruits. Therefore, it is advisable to adopt full seeds that mature naturally and fall off at a later stage.
２． 2 Seed germination characteristics
Elm seeds can be planted in the same year without the need for germination. From the matrix of different treatments, both group B treatment and group C treatment in the 3 group treatments found obvious signs of budding on the 7th day after planting, and the group A treatment was delayed 1 day. After 14 days, all three groups of treatments have undergone germination period, and the germination rate of group B treatment is slightly higher than that of the other two groups, reaching 94. ７％ 。 This may be related to the permeability and water retention of the substrate, there are more grass charcoal soils in Group A, less perlite, and the air permeability is weaker than B and C, but the water retention is high, while B has both air permeability and water retention. After 14 days, there was also a significant difference in the length of the hypocotyl on the three groups of treated seedlings, of which the length of group B was (30. ４±３． 21 ) mm, higher than Group C (28. ５±３． 14 ) mm, Group A is (26. ２±２． 75 mm (table 1). Therefore, in actual production, it is not advisable to land seeds too deeply, and it is necessary to ensure that the substrate can supply sufficient water during germination.
Table 1 Seed germination of large elm
From the perspective of germination rate, there was little difference in the treatment of the three groups, indicating that the large elm with full grains had high germination capacity, and the reason for the low germination in the natural state was the low seed fullness, poor matrix permeability and water retention. In addition, temperature also has a significant impact on seed germination, outdoor planting is generally lower than greenhouse planting, the actual production should be in the greenhouse or outdoors with thin film covering to maintain temperature and humidity.
２． 3 Seed seedling stage management
In the germination stage of large fruit elm, the internal metabolism of seeds is vigorous, the respiration is strong, the external environment is highly sensitive, and the root system is still shallow, and the ability to resist adverse environments is reduced, so the matrix and greenhouse environment should be paid attention to in real time. Generally, the moisture content of the matrix should be maintained at 50%~60%, the air humidity should be 40%~50%, the temperature should be 15~30 °C, and the loose matrix can provide sufficient oxygen to the roots. In the greenhouse concentrated seedling stage is also a high-risk period for disease occurrence, especially insufficient or excessive temperature and water control, prone to dry or rotten roots, bacteria and other phenomena. Therefore, to maintain the circulation of greenhouse air, use clean water for watering and replenishing air moisture, in order to prevent the invasion of germs, it is best to spray carbendazim and other disinfection once a week, if there is a rotten root phenomenon, while controlling the moisture of the matrix, spray 1% ferrous sulfate or xanthocycrin disinfectant.
２． 4 Seedling transplanting
When the seedlings reach 50 cm, they can be transplanted into the field, usually in the spring, autumn or rainy season. Spring planting begins to sprout when buds begin to germinate; autumn planting before or after leaf fall; planting in the rainy season with the start of planting, when the root system needs to be dipped in mud. In transplant cultivation, select excellent seedlings with straight and thick stems, high and short symmetry, full lignification of branches, developed root system, short and thick main roots, many lateral roots and whisker roots, full top buds, no diseases and insect pests, and no mechanical damage. The transplanting density is set on demand, and the planting can be intensive in the initial stage, and then it is pumped or retained in the second year according to the specifications required for afforestation. Within 1 month before transplanting seedlings, it is not advisable to apply fertilizer with excessive concentration, and fertilization at this stage can be used (0. ５±０． 1 ) % of urea, ( 0. ３±０． 1 ) % of potassium dihydrogen phosphate, etc., based on the principle of less diligent application.
２． 5 Post-management
In terms of management, we should mainly do a good job in loosening soil and weeding, fertilizer and water management, prevention and control of pests and diseases, pruning and shaping. After the end of the transplanting of slow seedlings, it can be properly topdressed, 2 to 4 times a year, and the last fertilization is before September, mainly phosphate fertilizer, to prevent seedlings from being frost damaged in winter. Loosen the soil and weed it from time to time, replenish water and nourish the roots. When the seedling is higher than 1. After 5 m, thinning, stubbing or auxiliary pruning are initiated to promote the formation of branching forms of the main and side branches of the seedlings, while making the seedlings thicker and stronger, in preparation for the shaping of the large elm in the Summer Palace. The large fruit elm itself has strong frost resistance, but the seedlings or newly transplanted seedlings should be properly cared for cold.
Fill the feet in early November before the soil freezes
Winter water, add soil to the roots, and wind barriers should be set up on the windward side of the wind. There are relatively few diseases and insect pests of large fruit elm, pay attention to elm poison moth, elm white edge boat moth, inchworm, black velvet scarab beetle, etc., it is advisable to cut off the branches of pests and insects through caressing management and burn them centrally, improve the planting environment, improve the disease resistance of plants, and should not use chemical pesticides in a large area.
3 Conclusion
Big fruit elm is an excellent ecological tree species and landscape tree species, the Summer Palace big fruit elm has become a unique scenery in the harmonious garden, its posture is beautiful, the leaves are luxuriant, especially in autumn the leaves turn yellow and red, the color is gorgeous, is a rare color leaf tree species. In this paper, the seedling technology of large elm seeds was studied, and the seeds with full maturity and full grain were selected and sown in a substrate with a volume ratio of 3:1 between perlite and grass charcoal soil with strong air permeability and high water retention, which could effectively solve the problem of low natural germination rate and survival rate. The growth of the large fruit elm in the Summer Palace is stable and adaptable, and it can effectively increase its growth rate and increase the morphology construction by adopting fine means such as loose soil weeding, fertilizer and water control, pruning and shaping, disease and pest control at the seedling stage and after transplanting to the field, laying the foundation for large-scale ecological afforestation and landscape application.